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GEOL6363 Carbonate Sedimentalogy - Day4 01-28-2023 PM
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00:07 Okay, we're at that point in segment now where we can start
00:14 applying a lot of the stuff we've about, not just today and
00:18 but also last weekend, uh, the rock record. And the first
00:26 we need to talk about is making jump from these younger carbonate systems that
00:34 by definition less than 10,000 years Most of them, as I
00:38 you know, less than 3 to years old. And talk about how
00:44 this relates to the real world, is the subsurface or the outcrops that
00:50 , we look at for guidance to we see in the subsurface. So
00:55 gets us into the world of carbonate and de positional cycles. And the
01:05 is sequenced photography. So the first here shows you the two different approaches
01:11 doing sequence photography. And with most don't realize is that both approaches were
01:20 essentially at the same time within Exxon . Okay. And the one that
01:27 all the press has gotten all the for decades is the so called systems
01:33 approach. This is the one that pushed by Exxon's research lab here in
01:39 . And this is, has its in seismic photography. In other
01:45 that looks at straddle geometries on seismic infer sea level change and basically tries
01:54 come up with a with a model you can take from seismic data and
02:01 to predict the finer scale of faces play relationships. Okay. And the
02:07 premise for this is twofold. The is that carbonates and classics behave the
02:13 way to sea level change. And second premise is that sea level is
02:20 prime driver for deposition. Okay. . That's even controversial. And
02:31 although probably more accepted by more people sealable has more an effect on classic
02:37 . I mean, of course, or clay flake doesn't care about the
02:41 of deposition. Right. It just moved around hydraulically by base level
02:48 But in the world of carbonates, I haven't convinced you from our last
02:52 of lectures that carbonate systems are different it's time for me to retire because
02:58 just uh there's no comparison. You can't you don't instantaneously shift carbonate
03:06 around, as you're gonna see. a lag time when we have a
03:10 change in sea level. There's a time for organisms to readjust to that
03:15 before you start producing sediment. So, what that implies is
03:20 yeah, while sea level is important for providing accommodation. While sea level
03:25 important for terminating some of these depositions , how you fill them up has
03:31 to do with what sea level is has to do with the local environmental
03:36 . Okay, so the system tracks uh actually started back in the seventies
03:45 this with the sequence the seismic photography the implication of strata. Geometries.
03:52 something about sea level change. And that evolved into eventually what people call
03:58 systems tracks approach. Where people thought level uh controlled the geometry of some
04:08 these packages of sediments for both carbonates plastics. Alright, they get
04:15 I don't know how much you guys about the seismic photography. I guess
04:20 going to get introduced to this eventually some geophysics class. But excuse me
04:36 lost my train of thought now. you look at the if you look
04:56 the uh there's a a PG volume memoir volume called number 27 is on
05:08 photography. And if you look at you look at what Exxon published back
05:13 in the seventies, you will see they thought sea level behaved like a
05:22 curve. Right? The sea level come up quickly like this and then
05:26 fall, come up gradually like this rapidly fall. Right? So you
05:31 at their sea level curves that they that volume. That's the way they
05:34 sea level. Okay. Which actually closer to the kind of suitable change
05:39 see in the pleistocene for the last million years where we have good knowledge
05:46 the timing, right? We know Pleistocene successions. We know their
05:50 We know when sea level dropped and like that. What happened is in
05:55 early eighties there was a guy and list his name here Mac Gov.
06:00 was a classic sediment ologists who worked the Exxon worked at the research lab
06:05 I worked And Mac was interested in classic sediment response to a different kind
06:13 sea level curve. Right? He posed the question. But what if
06:17 level doesn't behave like this? What it behaves more like this?
06:22 More of a sinus oil change in level, up and down through
06:27 And he posed that question and wrote proposal internally to the company, you
06:34 , asking if he could if they fund the research. Okay. Because
06:39 , we all did research projects that to be funded internally. And he
06:45 to Exxon's management and said we're not . Okay. So he went on
06:51 own time. He spent about a doing it on his own time and
06:57 modeled it and wrote up a little and transferred out. I want to
07:06 the boss of the two Canadian geologists going to talk about in a minute
07:10 in Calgary and uh this report sat for probably a year or so and
07:16 all of a sudden somebody picked it inside Exxon. And what that led
07:21 was this aspect of the model, sea level behaves like this.
07:26 They basically plagiarized his report. And now they treat sea level behaving
07:34 your story to leak. They talk uh sequence boundaries defined as on conformity
07:42 and how do they define an un back in the seventies and nonconformity was
07:47 break in deposition. Okay. That be due to a drop in sea
07:52 . That could be due to a in sea level. Okay. But
07:58 this model they redefined sequence boundary to a nonconformity created by regional several
08:05 Alright. That you had to drop . And so they're type one on
08:12 would be a situation where sea level below the platform margin. Okay.
08:17 a so called SB two sequence boundary would be where it didn't drop
08:23 it exposed some of the platform margin continental shelf but it didn't expose the
08:29 show. Okay, so that's where to the concept of sequence boundary comes
08:34 . They completely redefined the term to a surface of several exposure or its
08:43 relative conformity, which I've still never out what that means. All
08:49 What is the relative conformity of a conformity? I mean theoretically that makes
08:56 . Right. If there's exposure surface the platform, that's time equivalent to
09:01 in the basin. Right at that . But what is it? How
09:06 you prove it? You would never . Okay. There's no way to
09:10 the so called correlative conformity, but how they that's how they find
09:14 Okay, so later, after I'm to talk about the Canadian approach here
09:21 a minute, the Canadians started coming with the recognition that there are these
09:26 of sediments that are put together to up these reservoirs and these pack packages
09:35 exhibit geometrical relationships between each other. uh these guys, the Exxon guys
09:43 in Houston took those relationships and decided they could use the stacking geometries.
09:51 geometrical relationships between these packages to relate to a position on the seal
09:57 And so that's where the system tracks from. So the systems tracks are
10:02 as a hierarchy of vetting styles that certain geometries. Okay. And so
10:09 you're familiar with the classics model, probably heard all this terminology like paris
10:15 para sequence set, lamb in a in a set bed set. You
10:20 heard that? No? Okay. the class, if you read the
10:26 model that they published back in the , you'll see that they claim every
10:32 . Every classic sequence is made up the hierarchy of betting styles. The
10:37 unit is laminar like we talked about and laminate stack into what they call
10:43 sets. And lambda sets stack into they call beds and beds stack into
10:50 they call bed sets and beds that into what they call a paris
10:55 And paris sequence sets back into what call a sequence. Okay. And
11:01 they define the term sequence to be by un conformity, ease several exposure
11:08 or their correlative conformity and they wanted sequence to be thick enough to have
11:15 expression because for them they start with size. They don't start with the
11:20 data, they start with the And try to tell you what the
11:23 data should show. Okay, using model. So the system tracks you
11:33 listed here like high stand systems Track systems track these are comprised of paris
11:39 sets. Okay. With different stacking , I'll go through the stacking geometries
11:45 later. Okay. And you see they relate it back to a position
11:49 the sea level curve. Right? you know sea level. Let's just
11:56 here situation. We come out of low stand represented by the red
12:00 That's what they call the low stand . Sea level starts to rise
12:04 Like I talked about in the in modern. So the first phase of
12:08 related to that would be the high . The transgressive systems tracks okay.
12:14 that's going to be characterized by one of stacking geometry that they call back
12:21 and then sea sea level starts to . Okay? And they call that
12:26 high stand systems track. Actually. break it out into an early and
12:30 Hiestand Systems Track and early Hiestand systems is aggregation stacking geometry builds vertically because
12:39 saying you've created all this accommodation and you're trying to catch up,
12:42 the sea level and then the late stand would be the situation where sea
12:49 is starting to fall. You're starting roll over up here and the falling
12:54 level now causes your your pair sequence to pro grade and its appropriation stacking
13:02 that they relate to falling sea Okay so you see how they do
13:07 . If they know sea level they're gonna tell you what the stacking
13:11 should be. And if they don't steve level history, you're working from
13:15 rock data then they're gonna tell you the stacking geometry to infer what sea
13:21 is doing. Okay. Everybody understand I'm saying. I'll show you how
13:24 works a little bit more detailed or show you the pitfalls of this
13:28 For sure. Okay. Okay. this is what's ingrained in sequence
13:35 Alright. The one that doesn't get much press here in the U.
13:39 . Is the so called actually stick which was developed by two Canadian geologist
13:45 Winnie frank Stokes. And turned out McGreevey went up to work in the
13:50 office. This is all with this S. O. Resources.
13:54 One of the affiliate companies of Exxon Mac went up to to be their
14:02 and uh these guys were coming at from the other point of view.
14:07 coming out from the rock data. right. So you go to the
14:10 record. They had they were working these giant Devonian oilfields. Alright.
14:17 gone to water flood the water busted. They didn't understand the internal
14:24 of these reservoirs. And so this them to do detailed course studies to
14:30 a strategic graffiti from the bottom because that's what we do in rock
14:33 , right? We described from the up, we never stop. Start
14:38 the top and work down. You do that in carbonates because carbonates do
14:43 through time they shallow up. You want to see that relationship through
14:48 . And so this is called bottom geology. And it's a situation where
14:52 don't start with a preconceived model where assuming sea level behaves like this,
14:57 assuming the system tracks fit to position this hypothetical sea level curve. You're
15:03 with established principles of carbonate geology. . And you're building the des positional
15:09 graphic bottle from the bottom up. . And that's what produced this diagram
15:14 you see up here on the on the right. Okay. These
15:17 diagrams like this were all built from data. Alright. There's no seismic
15:23 volunteer just using established principles the carbonate to build a strata graphic faces
15:31 And we'll talk about this next I'll show you the economic benefits of
15:35 simple approach. I'm gonna introduce you the approach in this lecture, but
15:40 application is economically there's great economic application the simple approach. Okay. And
15:47 see that next week. Okay, I want to give you a little
15:52 of the history here. I could a couple of days, you
15:56 contrasting these two different approaches and um don't have the time to do
16:01 But what I, what I want do is, uh, as I
16:05 through this to show you some of pitfalls of using the system strikes approach
16:09 trying to use stacking geometries to infer level or assuming that a stacking geometry
16:15 to a certain type of sea level . Okay. I think you're gonna
16:18 how that falls apart with respect to . Okay, so, alright,
16:27 here's our two end member models that just finished up sort of summarizing based
16:32 what I showed you in the whole . And uh, we saw a
16:38 on a theme for the steep margin model where you get the stronger trade
16:44 and volunteers. We contrast the northern with keiko's you, I think you
16:48 , you have a good feeling around carbonate ramp model is put together.
16:52 , again, the limitation here is we're only talking about for most of
16:57 settlements here three or 4000 years of , which is not much geologically.
17:02 so we need to make the jump the real world. This is the
17:07 world. This is a quarry in Germany. It's in a sequence called
17:14 cock formation, the Triassic age sequence I'm going to provide more information about
17:21 later, but without going into any right now, If I tell you
17:27 more recessive intervals here are the same all faces. That is they
17:33 Same deposition environment and the more resistant that you see here in outcrop are
17:41 same faces. What do you see time? You see a pattern of
17:45 . Okay, these these faces packages over and over again. This is
17:51 positional cyclist city. Okay. And is the norm. Okay.
17:57 this is the norman overall shallow marine sequences. Alright. This is to
18:01 expected. And if you understand this is what we try to
18:06 Both from an exploration standpoint and from exploitation standpoint when we're trying to develop
18:13 of these carbonate reservoirs, like we'll about next weekend. Okay. So
18:20 I'm gonna do for this lecture is going to talk about de positional cyclist
18:24 . We're gonna I'm gonna share with basic observations. These are well established
18:30 and some of these as I are well over 100 years old.
18:34 then we're gonna talk about how you this from the rock data. First
18:38 this lecture and then our last lecture afternoon will be on logging seismic expression
18:47 we'll talk about how sometimes you can the well logs to break out some
18:51 these packages. Okay. I'll talk about some of the controls and then
18:55 tease you a little bit with some the application knowing that I'm going to
18:59 into this in much more detail next . Okay, so remember what I
19:05 before, lunch Walters law to explain we got that vertical succession of environments
19:13 on abu Dhabi. We went from to inter title to super title.
19:18 was an expression of walter's law 18 says the vertical sequence of faces in
19:26 rock record reflects the lateral sequence in deposition setting. What walter's law reflects
19:33 the tendency of carbonates to shallow up they get close to sea level,
19:39 do they want to do then? grade in a seaward direction.
19:43 so the more lambert faces bills out the more seaward faces through time to
19:49 that upward showing expression. Okay, the norm. But that's not unequivocal
19:56 because there's sometimes as we'll talk your carbonate system can't program either because
20:02 the bottom topography or because of what level is doing through time.
20:07 so don't assume every carbonate succession they don't. Okay, but most
20:12 them do. And they certainly would that in a in a wrapper,
20:18 slope angle environment. Okay, so me introduce you. I'm gonna avoid
20:24 the terminology here. You're not going hear me talk about paris sequences,
20:28 sequence sets. You're not gonna hear talk about maximum flooding surface sequence boundaries
20:33 things like that. Okay, just couple of simple terms here. And
20:37 first term is upper chilling sequence, I mentioned a little bit already.
20:42 is well established in the literature Exxon came up with their models and
20:48 it is is a orderly and confirmable succession of these genetically related faces.
20:57 , It's the basic building block for marine carbonate strata. But everybody forgets
21:03 people that worked at Exxon. Is the completeness and thickness can vary.
21:08 , I'm going to show you some showing sequences that are a couple of
21:11 thick. Okay, I'm gonna show some that are over 1000 ft
21:17 All right. This is not what wants to hear. Right? They
21:22 things to be of a certain thickness build to a certain hierarchy of thickness
21:27 has seismic expression, but using their this is the problem. Okay,
21:33 , the completeness of thickness can vary you need to appreciate that. And
21:37 of this is controlled by your fizz graphic setting where you sit relative uh
21:43 a deposition profiles. Fizzy graphic studying a local scale. Right?
21:47 it's the bottom topography that controls the and completeness of these upper trolling
21:53 Right? But if you can understand reservoir quality ties back to a faces
21:58 a position within this upper showing This is what you can exploit.
22:03 is what the Canadians exploited to better their carbonate reservoirs and to get more
22:10 and gas out of those reservoirs. , of course, the cyclist,
22:14 results from the vertical repetition of these chilling sequences. Alright, so,
22:19 see upper trolling sequences and stuff as as the whole thing. This is
22:25 whole esteem from keiko's platform. This a cut through part of the
22:31 This is not even consolidated rock. . This is unconsolidated sand, analytic
22:38 scalable sand. And you can see the base that's biter baited,
22:44 Looks like burrow subtitle carbonate. And then what is it?
22:49 Up to cross stratified, Right. the high energy active part of the
22:55 body system. So stable at the . Active shoulds. Okay. And
23:01 it grades up into a different betting . You see how the beds change
23:06 . They take on a general seaward planer stratification, anybody recall what environment
23:12 occurred in? Where do we see seaward dipping stratification in the beach?
23:22 . Remember we talked about sedimentary structures seaward dipping. Alright there be finessed
23:30 and things like that associated with So that's the beach. So what
23:33 we gone from borough subtitles stable to bedded, high energy active bulleted sand
23:41 a beach. Okay. And the way you can explain that is that
23:46 shoal built up the sea level to a beach and then it did what
23:51 pro grading out in the seaward direction order to explain how a beach could
23:55 out over the active shoal and how actors show could build out over the
24:00 equipment. Okay, so that's walther's in sediment that we don't know how
24:05 this sediment is but can't be more a couple of 1000 years old.
24:10 . And then here's keiko's to this the pleistocene. This is some of
24:14 pleistocene we visit on our seminars and place is seen as as good as
24:19 gets in the world because it's a climate. The pristine preservation of the
24:25 structures here Again, this is all grain stone. The base is modeled
24:32 burrowed. And then this stuff here so that's a stabilized equivalent,
24:37 a little bit deeper water. And this is the active show with beautiful
24:41 trough trough cross stratification. Okay, the active show. And then you
24:46 a switch again to to seaward dipping stratification. That's the beach.
24:53 And so upward showing succession. Which is only can only be produced
25:01 pro gradation, right? Where the had to build up and then start
25:06 the seaward direction. Okay, now beauty of this outcrop is you could
25:11 Walters law because you can Walters law that the beach and the offshore subtitle
25:18 time equivalent. Right? And they've this through time, right, build
25:21 over. Well you can stand on one of these layers here. You
25:27 stand on the fossil beach and you do what you can walk it out
25:30 the left to where this guy is and you have stepped into the water
25:35 the active show was. Okay. establishes the time equivalency between those two
25:41 . Remember how we're using the term . So rock reflective of environment of
25:47 . Alright, So this outcrop proves there's law. Right? Look at
25:52 . Here's the beach coming like And then, right, here is
25:57 transition to the offshore subtitle active show establishes the time equivalency nature. Put
26:04 little shot sam line here. We this shot sam line. Right?
26:07 faces change laterally nature. Put it there for us. All right,
26:12 of interesting. All right. It's a it's a c imitation effect,
26:16 looks looks pretty interesting. Right? it would be right there where you'd
26:20 it. All right. Now, would Exxon call this? Exxon doesn't
26:26 the term upward chilling sequence. They these. They call these they call
26:30 a pair of sequence. Right? say, well, your report showing
26:33 basically our pair of sequence. And I would tell them that.
26:39 , if that's the case, you define it like that. You defined
26:43 as a hierarchy of betting styles. told me you have to see lambda
26:48 sets, beds, bed sets, they would have to stack into a
26:51 of sequence. So, you go to this. Go show me where
26:55 lamb in a lamb in a sets . Bed sets are You can't do
26:59 . Okay. You just see a showing character culminating beach. And then
27:05 the other problem. There's an un by their definition, there's a several
27:10 surface under this rock here. That's the last low stand of sea
27:15 when sea level dropped 120,000 years, 100,000 years ago, went down.
27:22 . Came back up. Sorry, got the dates wrong. That's an
27:27 pleistocene. Several exposure surface sea level . Then it came back up and
27:33 flooded the top of this uh flooded here 120,000 years ago. Okay.
27:41 so this is 100 20 140,000 year marine analytics and deposition and beach.
27:48 . And then sea level dropped So there's a nonconformity on top of
27:52 . So here's a pair of sequence their terminology. That is bounded by
27:59 on conformity, which was also their of a sequence. Remember they want
28:06 to be thick enough to have seismic . And they pick their sequences based
28:11 their straddle geometries and their inferred on . Alright, so, you see
28:15 problem here, not only is it pair of sequence using their terminology,
28:20 it's a sequence doesn't make any They box themselves into this situation.
28:28 it's really ironic that they hate the because everything is too thin.
28:36 But this is where we know what level is doing, right? In
28:40 Jurassic, you have to make differences sea level change, Right? But
28:44 we know it's just it's just so that they never they never wanted to
28:51 with the pleistocene because things are just complicated. Too thin. Right?
28:57 even though we know what sea level doing through time. So it's a
29:01 , you see some of the problems and this is why I don't use
29:04 terminology. I stick with the Canadian . Very simple approach. Okay,
29:09 trolling sequence. And then we're going use two other terms here. Major
29:13 contact and minor cycle contact. And gonna be the end of it.
29:18 for building some of these details Graphic faces, bottles. Okay,
29:25 here's a situation from the Jurassic smack formation. This is one of the
29:34 oil and gas productive sequences around the gulf of Mexico during the Jurassic.
29:40 look at what you have here. is based on continuous core data of
29:45 1500 ft thick. And you can it starts off at the base with
29:51 parallel laminated lime mud stone with some solicitor classic still stone mixed in grades
29:58 . You lose the classics, you in deeper water carbonates that get burrowed
30:03 can be laminated and then you come basically you're coming up the ramp.
30:07 would never use this term shelf but what they did back in the
30:12 And what do you get into? get into this shallower subtitle environment
30:20 colloidal skeletal pack stones and wacky And then you get into show complex
30:27 and stable. Like we talked Right? The outer would be the
30:31 the stabilized equivalent. The so called part of the show would be where
30:35 have the high degree of preserved stratification over land by the critic Red Bet
30:41 critic Laguna carbonates, that's the back lagoon and then everything is over land
30:45 tidal flat with evaporates. Okay, what have we done here? We
30:50 load up. Right. We've gone a deeper water basin, all
30:54 Shall it up to the closer to shore lines where we get the the
30:59 energy you would sand body system developed behind it and then evaporated title flat
31:06 that. Right. Just like I you for abu Dhabi basically it's the
31:10 relationship. But look at the thickness over 1000 ft thick. All
31:16 And this is the other problem. . Again, by their definition,
31:22 would be a pair of sequence. ? One upper showing sequence or they
31:27 say, you know, current sequences equivalent to upward Children's sequence, but
31:30 is 1000 ft thick. All Now, there's no argument that this
31:36 not the norm. Okay, Most these opportunities, sequences don't get this
31:41 , but it shows you if everything's concert, right, deposition, sea
31:45 change local tectonic subsidence. You can these thicker packages. Okay, so
31:52 appreciate that. And then you see problem in the rock record is where
31:56 people pick formation context? They don't it on the basis of time strategic
32:02 . They pick it on the basis the mythology change. Okay, so
32:06 Buckner formation is picked on the basis the first appearance of an hydrate.
32:14 . And they think the anhydride is with the saka or maybe the
32:20 And that in itself is dangerous too there's an hydrate down here in that
32:26 some of that analytic material. But this is another problem here,
32:30 People break package, genetically related They break it with formation terminology.
32:37 , So sometimes the formation terminology has time significance at all. Right.
32:43 just a change in mythology. So appreciate that. Okay, so,
32:52 said that, let's let's talk about two member models and member models we
33:03 talked about from the modern right. showed you an example like this from
33:07 northern Bahamas. Any one point in . Shell water platform dropping off into
33:11 water basin where it had reef We had the debris behind it,
33:17 ? The re flat, but we no allergic sands associated with it.
33:22 the system operate for some period of . What's going to happen? The
33:26 gonna build up. Don't want to above sea level. So it's going
33:29 do what it's gonna build out laterally the right? It's gonna pro
33:34 And so with time, the brief gonna pro grade to the right,
33:39 gonna be piggybacked over by the platform . And the title flat on top
33:44 that again, this is with time subsidence, right? And what if
33:49 come back in 50,000 years in court you would see something like this.
33:53 see the deepwater offshore faces at the platform margin right here and then the
33:59 interior on top. Right. That's law. So that's that's what you'd
34:05 in a steeper margin platform system. what's the limitation here? The limitation
34:10 the whole and how deep it Right. What did I show you
34:13 the Bahamas? Thousands of meters of depth. Right. And you see
34:19 problem here, a reef can't pro to the right until it fills the
34:23 in with its own debris. That's lot of filling in to do.
34:27 , so in this model, you expect to see a lot of lateral
34:31 because of the depth of the The good news is most of our
34:36 in the rock record. We're not the scale of the basins we have
34:39 in the modern. Okay, so lower that, you lower that threshold
34:44 the water is not that deep, it's easier for this stuff to pro
34:48 laterally. Okay, contrast that with ramp model, this is the pattern
34:53 showed you at any one point in , it doesn't take much for these
34:57 energy carbonates to get up to sea and once they get up there,
35:01 gonna shoot out to the right and gonna pro grade and produce a sort
35:04 classical upward showing sequence. Right? the slope angle, the local fizzy
35:09 setting controls appropriation, right degree And you have to keep that in
35:16 when you're when you're thinking about some these relationships. Okay, so let
35:21 share with you some observations here. first is the sediments carbonate sediments respond
35:29 changes. What controls that? It's graphic setting. Okay. Both on
35:35 global and local scale. If sea was a simple control, like Exxon
35:42 right that all you need to know what sea level is doing through
35:46 then we should have seen a mirror of de positional patterns across these
35:51 Right? We should not have seen variability. But I showed you
35:56 didn't I? I showed you how width of the US sand bodies varied
36:01 a few kilometers here to 25 kilometers . I showed you, mud accumulates
36:06 the islands but not on the open of the platform. Um reefs only
36:11 on the open ocean sides. these are all local environmental controls that
36:18 deposition. All of these environments experience same sea level history, but they
36:23 differently because of the local environmental So positive topography, like the
36:30 negative topography, like the deep water famous windward leeward. Right. All
36:36 these are important controls. The kinds drivers for deposition, tidal currents
36:44 Trade wins. Okay. And then saw how keiko's is so much different
36:50 northern Bahamas. Right? They experience same sea level history too.
36:55 so that's the key. That's a difference between carbonates and classics. And
37:00 the problem with Exxon's model. When applied to carbonates, they basically suggest
37:05 don't just suggest they say carbonates, respond the same way. Okay.
37:10 is total Bs. So, and illustrate this, here's a two measures
37:18 from Canberra or division sequence that outcrops the western side of, of
37:25 on the eastern side of Canada. right. You ever get a chance
37:29 go to Newfoundland? It's, it's it. It's just incredible, beautiful
37:35 or province. And um, but the west coast of the island or
37:40 great outcrops where you can see this of stuff. And this is,
37:44 are two measures sections, Right? one, one is taken near the
37:50 margin, one is taken further inboard both of them at the base have
37:55 older part of the sequence where, , jeez, get off my
38:09 Thank you. Um, both of have uh, that the base,
38:16 flat deposits. Okay, Remember the pebble conglomerates I showed you on the
38:21 , the rip up class get Okay, so that's the evidence that
38:26 are tidal flats at the base Alright, and then what happens?
38:29 go from red to the darker That's a deepening effect. Right,
38:33 sea level came up sea level created so called accommodation. All right,
38:39 , how do we fill it Well, in this sequence on the
38:42 , we don't have a lot of water blue. Right. We have
38:46 go into a little bit shallower subtitle and then look how quickly we get
38:50 the thick cross stratified grain stone. , These are a little grain stones
38:56 then they built up the sea level they've got a tidal flat on top
38:59 that. Right? You can only a title flat on a grain stone
39:03 it builds up to make an Okay, So this is obviously grain
39:09 dominated succession? Right? Overall, energy environment of deposition. Okay,
39:15 then contrast this one which turns out be 50 miles in from this one
39:21 the right, it shallows up the flat because it's got the same kind
39:25 fabric at the top of the pebble conglomerates. But look what fills
39:30 in. It's all subtitled carbonate, it's all low energy MMA. Critics
39:34 carbonate. Very little uh carbonate sand . Most of this is probably thrown
39:41 . Okay, so you see what here both of these shoulder up.
39:46 ? But which one is higher Which one is the lower energy?
39:51 the one on the left is lower . Why the difference Despite having the
39:56 sea level history, The grainy sequence closer to the basin margin where during
40:03 cycle of sedimentation you saw the effects ocean oceanic conditions, right? Tidal
40:09 and things like that. But the sequence being up on the inner part
40:14 the platform, never saw exposure to high energy conditions still shallow.
40:19 But a state low energy democratic in nutshell. This is the northern Bahamas
40:26 . We just talked about right. for the margin for grain stones,
40:30 the platform interior. But the point I'm trying to make is sea
40:35 Had nothing to do with the composition these sequences. Okay, It has
40:40 do with your setting and the influence those oceanic drivers of deposition.
40:47 you understand what I'm saying. This is the environmental control on carbonate
40:53 . Second observation is most shallow marine . Carbonate sequences report showing cyclical.
40:59 most basic sequences lack obvious physical expression cyclist city. So, here's a
41:06 cross section schematic cross section of a million barrel oil field in western Canada
41:15 we're going to talk about in more later. And you can see how
41:19 packaged together into a number of these packages with reef deposition on both sides
41:26 then shallow subtitle entitled fat deposition occurring the interior part of this complex.
41:34 , and you see this nice expression these repetitive cycles. Right? This
41:39 this is what is to be expected an overall shallow marine carbonate succession.
41:45 , I'll come back and explain this more detail. Later contrast that with
41:49 overall deeper marine succession, this is Austin chalk and corps in south
41:55 Austin chalk is upper cretaceous. It's part of a deeper, so called
42:01 or down the ramp. Uh deeper successions, plastic dominated. Okay,
42:08 look at the core here, you color changes. You see some differences
42:15 strategy. You see some stratification You see a lot of observation.
42:19 of the core breaks up. That's either is due to fracturing or let's
42:22 maybe to a little bit more are material. But what doesn't change
42:28 In contrast to this where you saw changes right? Faces changes laterally at
42:34 changes vertically. Excuse me, What change here? The faces.
42:41 It's all the same environment of There's no physical expression of cyclist
42:47 We're too deep. Okay, any level changes that create the potential for
42:53 city have no effect in these deep successions. Okay, and so there
42:59 important implications here about how you correlate overall shell or water successions to a
43:05 water succession. Okay. And then and final point here is most shallow
43:14 carbonates, what we call regressive. term regressive means the deposition occurred during
43:19 still stand are slowly falling sea Transgressive carbonates are rare absent in the
43:25 record. Transgressive. The term which I think I defined for you
43:30 your notes set that I'm skipping Transgressive means that you actually deposit your
43:37 during that rising sea level. And that usually doesn't happen.
43:45 You can do it in classics, ? You can move shale around during
43:48 sea level. Right? But you do that with carbonate. So,
43:52 gonna prove that to you in a . All right. So to illustrate
43:56 I'm talking about here, there's a . So just explain that. All
44:02 . So, here's the example that want to talk from to show you
44:06 . All right. This is a section from the Mississippi and logical formation
44:12 outcrops in Montana and in the some of this stuff is productive.
44:19 , we're coming out of this showing sequence here capped by a grain
44:24 and the transition from yellow to That that changes a cycle contact where
44:31 gonna call a cycle contact. And a cycle contact because we abruptly
44:37 Right? And we had to abruptly because your grain stone gets shut
44:43 right? If it was a slow sea level, you're carbonate system would
44:48 able to respond to that. Of , I forgot to tell you a
44:51 of things yesterday, we were talking those, a little grain stones from
44:56 Bahamas. Remember the title bars? up to about 30 ft thick.
45:02 , separated by channels that are up 30 ft deep. Right? Not
45:06 the channels are that deep? Not the shoals are that thick, but
45:11 have actually measured how much, what rate of sedimentation is the accumulation rate
45:17 those. Ooh, it's they accumulate foot every 400 years. Okay,
45:22 faster than some of the reefs grow . Okay, so envision if your
45:28 level is slowly rising like this, , A new it sand body
45:33 a reef is going to keep pace that. Right? So in order
45:36 terminate a high energy grain stone or reef, you have to do what
45:42 have to pop up sea level pretty . You don't have to go hundreds
45:45 feet, but you have to pop up enough to get it out of
45:48 zone of agitation. Okay, And how you shut down your grain stones
45:53 sometimes how you drown out your Okay, so that's what's implied
45:57 A major, relatively rapid rise in level. Okay, that shuts down
46:02 grain stone. That creates the accommodation that people talk about and what's the
46:10 phase of deposition that comes in? not even carbonate, it's classic.
46:14 these are silty mud stones, silty . Okay, that's the transgressive
46:19 That's the stuff that came in with sea level because the clay flake is
46:23 gonna get moved around by base level . Alright, And then there's a
46:29 time before you can deposit the orange on top of that because this is
46:35 water carbonate deposition related to the fauna lived in that environment. Okay.
46:42 you can't do this instantaneously. There's lag time. The lag time comes
46:49 play after you deepen. You have shut down your classic influx. You
46:54 to clear the water, right? carbonates generally in Clearwater. And then
47:00 do you have to do? You to allow time for organisms to adjust
47:03 that environment and start producing sediment by time, sea level is essentially
47:09 Okay. And that's why we say the orange to the top of the
47:13 , this is the regressive phase, means it was deposited during still stand
47:18 maybe slowly falling sea level at the . Okay. You see what I'm
47:23 ? So, in carbonates, when have these major sea level changes applied
47:27 that faces change. You don't magically stuff around. Okay, there's a
47:32 lag you need time for for organisms adjust to that newer deeper water
47:39 And I'll prove this to you in minute. Okay. Okay. And
47:45 recognition. Well, from the rock outcrops, we look for the the
47:52 upward stacking of these upward showing Right? The faces contacts tend to
47:58 gradation all because we're gradually shallowing. ? We're transforming from one environment to
48:04 other. And now let me introduce to the this other terminology. The
48:09 contact cycle contact is wherever we see deeper water faces, abruptly overlying a
48:17 water faces. Okay, we're gonna that cycle contact for time significance.
48:23 gonna we're gonna treat it as a for correlation, recognizing that how far
48:28 can correlate laterally depends on the magnitude the, of the, of the
48:33 level change. Okay, I'll go this in more detail in a
48:38 And then the cycle contacts, especially major cycle contacts, we have the
48:42 deepening effects. Those contacts tend to sharp and along with those sharp contacts
48:50 to come these regional extensive hard which is the proof that there's a
48:54 in time between termination of the underlying and the next phase of deep water
49:01 , that you don't get instantaneous deposition away. If you've got that hard
49:06 there, you need a time to the hard ground to board to entrust
49:11 . Right. All of that had happen before the first phase of deep
49:14 carbonate or shell deposition. Okay. then internally, most of these uh
49:22 uh upper strolling sequences show internal probe geometry, right, obeying Welker's
49:30 something that you would expect to Okay, alright, so here's the
49:35 approach. Right? So this is Wendy and Stokes approach. This is
49:39 they zoned, jeez five or six these major devonian limestone reservoirs in
49:47 Canada I got involved in doing this of work with some of their
49:52 I also did this on my own a consultant later for S.
49:57 On some more complexity, altered goldstone . Alright, we'll talk about that
50:03 little bit. All right, But what we mean by cycle contact.
50:11 where a deep water faces abruptly. lies a shallow water faces.
50:17 And they broke out two types. and minor. Alright, so what
50:21 be a major cycle contact? We up to a tidal flat and then
50:26 bottom falls out and we go back a deep water basin. All limestone
50:30 . Right, that's a major A major environmental change from shallow to
50:35 deep water. And we're going to that contact as a timeline. And
50:40 going to use it for correlation by that the first phase of basil limestone
50:46 is time synchronous over a large area this is a major flooding.
50:51 So you're gonna flood over a large pretty quickly. And so that first
50:55 of deep water deposition should be time . Okay. And you can see
51:00 numbers here, we correlate the cycle with the well controlled for tens of
51:12 , sometimes all the way across a ? Say, the scale of the
51:17 Basin and the western US. And then what would a minor cycle
51:22 be in a situation where we have built up the tidal flat and then
51:28 deepen, but it's not a major , right? We go back into
51:32 subtitle, say burrow lagoon or something that. That's deep over shallow but
51:38 a great magnitude of deepening. So the the the the if you're
51:43 to correlate this, you're gonna find these contacts maybe correlate for hundreds of
51:48 or a few kilometers at best because is not a major deepening effect.
51:52 understand what I'm saying, but the is this is how they built those
51:57 time strata, graphic, faces, that I showed you in the first
52:01 . Okay, so it's at the cycle contact where you also typically get
52:07 widespread brain are grounds which proves that is that break in deposition between say
52:13 flat and the initial deep water basin faces. Alright, so let me
52:20 illustrate this a little bit. I a situation where um you can see
52:29 stuff building up, right showing up sequence for this. This is modeled
52:34 the Devonian western Canada for a platform a reef deposition along the margin basically
52:41 is the lower re four. So up into the middle re four soap
52:45 the reef margin and right here the falls out and what sits right on
52:51 . Remember naturally the term modular was burrowed pressure solved fabric, the muddy
52:58 material. Right. That's in the that would occur below the lower
53:02 So right, if he had enough here at the bottom, you see
53:05 modular mud stone beneath this. so we've deepened and return to that
53:12 basic environment. That's by definition a cycle contact for them. And this
53:19 cycle contact correlates all across this Okay. Actually correlates from platform to
53:25 to platform in some of these devonian basins in Alberta. Alright, so
53:34 the details of what I just showed . Alright, here's the rock
53:38 Lower four slope Esma critic with little uh storm atop roids. Right.
53:45 the plate corals yesterday in deeper Okay, so that would be equivalent
53:50 those. So that's the lower re slope. Then it grades up into
53:55 a critic limestone but now with more branching drama top roids. Or a
54:00 head strum strum atop its head like troma. Top droids which are like
54:07 modern day head corals we talked about , that would be the middle part
54:11 the force. So no reservoir quality because everything's a critic and then it
54:16 up into the high energy reef This is a reef margin upper
54:20 So the thick tabular format operate bound . The member thick tabular is the
54:27 morphology and you got roots, stones grain stones associated with it. That's
54:31 reservoir and then here's where the bottom out. Alright, there's your notch
54:38 line mud stone. That's the major contact. This is also where you
54:43 a regional hard ground developed marine cemented and encrusted. That's a little scalping
54:50 there represents right? You're losing your scraping and and boring into that
54:57 which is part of the definition for marine hard ground. Alright. All
55:03 . Look at look, this is the platform margin. Remember we talked
55:07 reefs yesterday being really competent environments. ? They have the potential to produce
55:11 lot of sediment per given unit of . We'll look at the thickness relationship
55:16 . Right. This reef related cycle tens of meters thick. Okay.
55:22 then it's terminated by this major deepening right there. This contrast that with
55:30 platform interior, this is the time . You're just a few kilometers in
55:34 that. Well in the previous slide now you're behind the reef margin.
55:41 ? You're in the lagoon and the is completely different. It's dark and
55:45 critic or light democratic depending on how it is. And what's the organism
55:50 lives here? It's a little stick branching storm atop a ride called
55:56 It looks like those little stick like algae. I showed you last weekend
56:00 I were talking about the classification scheme now, things packed together.
56:06 but it's not a red algae, called the storm atop Right,
56:11 And they like to live in quiet environments. Okay. And so what's
56:17 here is we're shallowing up to explain color change and then what comes in
56:21 top of the lagoon. This is title flat faces with the cryptography,
56:26 of finesse tral porosity. Okay. sometimes in speech deposits made up of
56:33 debris of amphora. But you can the shelling effect here. Right?
56:38 is an upward shelling sequence again. look at the thickness compared to what
56:42 just showed you for the reef margin best. Just a few meters thick
56:47 the most. Sometimes just a few thick. Okay. See the difference
56:54 is the lagoon, right? This not a competent high energy environment.
56:59 you can't produce as much sediment for same period of time as you do
57:03 the margin. But when you look cross sections in the literature, how
57:07 times do people show you a platform they show you layer cake, strategic
57:13 , right? Everything's the same thickness the way across the platform. It
57:18 be Okay. The reef is always to be thickest. Right? Or
57:23 energy grain stone is gonna be thicker then that time equivalent unit is going
57:27 do what it's gonna thin back into inner part of the platform interior
57:33 It has to there's no way you maintain the same degree of sedimentation in
57:39 quiet water setting compared to the high margin. Okay, so you need
57:44 appreciate that when you're correlating from one of the platform to another part of
57:48 platform. Okay. And then I the internally, a lot of these
57:56 chilling sequences show probe rotational geometry. an example from the lower cretaceous in
58:02 . The formation is called the torpedo . We're coming out of a uh
58:09 faces. Okay, represented by dark . We shallow up into the high
58:15 platform margin, reef related faces which is over land by the outer
58:20 of the platform interior, then over by the inner part of the platform
58:25 and then the bottom falls out right . The gray is la pena
58:30 that's a marine shale that terminates this sequence. Okay, so one upward
58:36 sequence. Look at the scale that's 800 ft thick. One upward
58:40 sequence. 800 ft thick. Okay Jack Conklin, who's author on this
58:48 part of a master thesis. He's together a number of measures, sections
58:53 from outcrop in northern Mexico. And was able to demonstrate that the torpedo
59:00 what that steps up and out through . Right, strata graphically out into
59:08 basin. That's a classical internal pro . All geometry, right? Just
59:14 the reef or follow the sand Right? You see it stepping up
59:18 out strata graphically. That's upper showing procreation. Okay, that's what you
59:25 . That's the internal geometry that we see. Okay, now look at
59:29 scale bar, that's 100 kilometers scale . Not for the shark. There
59:35 large sharks in the cretaceous, but weren't that big. But obviously the
59:41 bars for the lateral pro gradation. have to be impressed by that amount
59:45 procreation. That's a couple 100 kilometers lateral pro gradation. Okay. And
59:51 know, this is not a bahama style of deposition, right. It
59:56 be the basin off to the cannot be that deep in order to
60:00 that kind of lateral appropriation. so remember lower the slope angle a
60:06 bit or shallow. The basin makes a lot easier for this stuff to
60:09 grade laterally. Okay, and then at look at this part of the
60:15 back here. The purple intervals you here are tidal flats and sometimes with
60:22 . So it makes sense. That you get title flats back here
60:25 the inner part of the platform. do you get tidal flats out here
60:31 to the platform margin? What would have to do? Well think about
60:41 right. What's the first requirement for a title flag? You need a
60:51 . You need something on which to the sediment, right? And then
60:55 need a delivery mechanism. You need source offshore. Okay, so to
61:00 up to put a tidal flat or put a coastal Selena ap writes close
61:06 the platform margin. You had to topography here. You had to have
61:12 of the reef for part of the body build up above sea level.
61:15 I showed you this yesterday, right Belize, I showed you the islands
61:19 on top of the title on the lap So once you pop that up
61:26 then any storm that comes this way left to right is going to take
61:30 settlement and do what push it up that backstop, make the title
61:35 which is then going to do what grade into the source of the
61:39 Right. Just like andrews did just keiko's did. Okay. Did you
61:44 that? So appreciate, you everybody thinks of apparatus and tidal flats
61:50 occur way back in the inner part the platform. Not necessarily right.
61:54 you can build the right kind of and you have the right mechanism to
61:59 sentiment, you could get these things very close to the platform margin.
62:07 , Alright then I mentioned that at major cycle contacts. This is where
62:14 can develop these regional extensive marine hard . Okay, so yesterday we were
62:20 about the politic stuff, I told that you could get patchy marines imitation
62:25 scattered hard grounds on the sea floor any one point in time because you
62:29 stabilize the whole sand body at any point in time. Alright, so
62:34 kinds of hard grounds here are reflective shallow water conditions, right? Where
62:40 create local zones of stability long enough start stabilizing and cementing. But what
62:46 when you have a major sea level where you go from grain stone into
62:51 art salacious lime mud stone at that , which is a by definition a
62:57 cycle contact. What happens is between termination of the grain stones,
63:06 By deepening and the first phase of water are delicious mud stones represented by
63:13 . Between those two events, there to be a time lag long enough
63:19 marine cement the top of the grain , right? Which is the hard
63:25 and then bore it and encrusted, is the definition of green hard
63:29 All of this has to happen first the first phase of our delicious lime
63:35 stone. Okay, so this is proof. This would prove that there
63:40 a time break between when you change level and your first phase of deep
63:45 deposition, that it's not instantaneous, it would be in a classic
63:50 Okay, everybody understand what I'm Yeah, so this is a different
63:59 of hard ground. These are those , regional, extensive hard grounds that
64:03 in deeper water, taking advantage of period of non deposition where you slowly
64:09 seawater through to get some marine cement create the hard ground you board you
64:15 all of that had to happen before first phase of deep water deposition.
64:20 , so here's here's here's an example what I'm talking about. This is
64:26 the cretaceous in central texas and this part of what we call the Edwards
64:33 or Edwards group in central texas, showing upward sequence developed along the margin
64:39 one of these little sub basins in texas. And you shall go up
64:44 the high energy analytic grain stone and change from yellow to light blue.
64:50 the major cycle contact where you deepened . You shut down your brain stones
64:56 then you end up shallowing back up the Edwards progres back out the next
65:01 of sedimentation. Okay, so let's at that contact between those two units
65:08 here it is and Corey, there's high energy cross stratified a little grain
65:14 , there's a sharp contact and then a deeper water. Keys valley moral
65:20 then that shallows back up into shallow Edwards related lime stones. Okay,
65:26 that contact looks like this. Um crop Corey before Cory's don't exist anymore
65:35 have been filled in with the housing on top of them now. But
65:40 is well documented literature. You can the top of the grain stone.
65:46 solo grain stone is cut by Okay, these are boring related to
65:53 and barnacles. Okay. And then surface is plastered with oysters. And
66:00 if you look at this intense you see the first phase of fibrous
66:04 , fibrous or agonized cement now replaced calcite. Okay, so everywhere on
66:11 surface of the sand body walked or , it's like this regional extensive marine
66:18 . Okay, you don't do this shallow water, you do this.
66:22 interface between shallow and deep. so that's the evidence that all of
66:27 had to happen in this photograph. of that after the US sands were
66:33 , the sanitation boring and crusting, that had to happen before the first
66:37 of keys valley moral deposition. and that's what makes carbonates different than
66:44 . Right. This is a classic . The shell would have come right
66:48 on top of the sandstone, with that changing sea level.
66:57 let's take a little break. We take our 15 minute break here,
67:01 2 15, we'll start back up 2 30 we'll finish up this discussion
67:07 then a couple of last lectures. , let me let me come back
67:16 the two end member models that we've talking about right there in the shallow
67:21 carbonate platform dropping off abruptly into a deep water basin versus the carbon
67:27 And let's consider the expressions of the expressions of cyclist city with respect to
67:35 along these depositions profiles. Because I you to appreciate this because I think
67:41 the rock record. Uh if you're a hard time trying to understand your
67:46 de positional setting. Sometimes you can the scale of cyclist city to sort
67:50 figure out at least crudely where you , right, whether you're along a
67:54 margin or whether you're further back up a platform interior setting. Okay,
68:00 we'll start with the steep margin. system will start with a cartoon
68:04 And uh where do you always get best expression of the finer scale cyclist
68:10 ? It's always in the inner part the platform. This is the least
68:14 environment. Okay. Any minor change sea level change sea level by a
68:20 or two? That has a dramatic on the environment sometimes. Okay,
68:25 this is where you produce what people the classical 123 m thick cycles.
68:30 these cycles nicely correlate all the way when you're back here in the platform
68:36 , but you lose the ability to correlate them once you come up onto
68:40 platform margin. Okay, so the margin is characterized by a more competent
68:48 of faces, Right? Either grain or refill related deposits. What that
68:53 is for a given unit of right, they evolve a greater thickness
68:57 to the same time period in the interior. So what that means is
69:03 the platform margin and this is where generate these thicker we're showing packages.
69:10 ? A thicker cycle. Right? is where you get the classical 10
69:15 m thick cycles. All right, they're going to be time equivalent to
69:20 a number of these smaller 123 m cycles. Okay, and so what
69:25 means is when you're trying to correlate stuff and you come up onto the
69:29 margin, you'll never be able to physically where that timeline goes into the
69:34 . Right. Does it go Does it come straight across? Does
69:37 come up? Okay. You can't that because at this scale you're well
69:44 the resolution of bio strategic graffiti, ? Bios photography, you know,
69:49 scale of resolution for bio strategic griffey on whether you're dealing with paleozoic or
69:55 carbonates in the paleozoic. What's the zone might be 1 to 10 million
70:00 duration? Right. Well, how carbon it could you put in the
70:04 to 10 million years. Right. even when you get into the tertiary
70:09 you're talking maybe bio zones of 500,000 using the forearms or the co
70:14 How much settlement could you put in water in 500,000 years? I
70:18 you see what I'm saying. So well below the resolution that you would
70:23 get with bios photography and you still know how to correlate this stuff.
70:28 . And then of course, in water, right? Any sea level
70:32 minor wants to drive the cycles back or the bigger sea level changes that
70:37 the cyclist e on the margin. still not gonna have any effect on
70:40 deeper water basin all settings. So no physical expression of cyclist city in
70:45 basin. That means also, you correlate those major cycle contacts down into
70:52 water as well. Okay, so me, let me show you what
70:56 talking about here. All right. this is the Permian reef complex in
71:00 texas. I showed you the castile that filled in the hole.
71:05 The evaporates that filled in the Delaware here. So let's go back to
71:10 getaway formation. All right. The part of the Guadalupe in here and
71:15 getaway was actually a carbonate ramp. let's just look at the getaway and
71:20 what happens here. We go to goat seep becomes a little bit more
71:24 angled and then look what happens. evolve into a steeper and steeper margin
71:29 succession by the end of capitan reef , the whole out here is estimated
71:35 be anywhere from 1500 to 1800 ft water depth. Excuse me.
71:45 so here's the, here's that I was talking about where the ramp
71:48 this, right? It changes into state margin platform. Okay, that's
71:55 uncommon to see in the rock Now, let's just look at the
72:00 gonna look at the cyclist expression So there's the basin out here,
72:04 in with deep water carbonates and blew lot of classics shown by yellow and
72:09 later by the evaporates the reef. capitan reef is made up of these
72:15 sponge and I don't know if you to aphids I showed you that problematical
72:21 cal curious something, right? People it's probably some sort of calculus
72:26 That creates some of the riffraff The reef shows through time, but
72:34 no obvious break in deposition here. a gradual showing. So the organisms
72:39 . You go from deep water salacious to shallow water cal correa sponges to
72:45 aphids and Phil Lloyd algae. The whole reef is showing. But
72:49 you look at an outcrop, it's all massive. You don't see any
72:52 in deposition. Okay. And then equivalent to that are these formations back
72:58 called seven rivers, Yates and tansil are made up of the smaller scale
73:03 m thick cycles. Okay, so just take a look at how this
73:07 is put together. So next time you get a chance to go to
73:12 Guadalupe National Park, you can, can, there's a famous geology
73:17 Now, I don't know if you've of this or not, but there's
73:19 geology trail that they put in that can walk up uh and actually walked
73:24 of the basin up through the Soap up through the reef into the
73:28 reef sediments. Okay. You can the whole showing sequence by walking,
73:33 mean it takes a whole half a to get up there and part of
73:36 half a day to get back. worth it if you've never done
73:40 And, but to see the straddle , you have to walk back into
73:45 canyons. So this is Mckittrick Canyon the this is the Kitchen Canyons,
73:50 the geology trail is here. There other canyons like Slaughter Canyon, which
73:54 appropriately named. Alright. Uh, you can do this as well.
73:59 . So, but what you have do is you have to walk about
74:02 miles back in. You have to up a couple 1000 ft to get
74:06 view. Okay. And so what you looking at here? Well,
74:10 looking at here is the platform Right? This is the stuff that's
74:14 to the Yates or Tansil or seven , depends where you're at on the
74:19 . All right. These are these 123 m thick cycles. You see
74:23 well bedded character. That's basically the city. Alright. And what are
74:29 ? These are shallow water platform carbonates that great up the classics and
74:33 repeat over and over again. So they shallow up. And then
74:37 comes in on top are classics and you repeat it. You deepen,
74:41 go back into carbonates classics. You over and over again. Alright.
74:47 , if you look at the betting , trace the betting, you're basically
74:51 the times photography, right? The cycle contacts are the timelines for
74:56 You can beautifully correlate all through back . Okay. But then what happens
75:01 you come up onto the reef? the massive rock right here? That's
75:06 capitan reef and look what it's done time. It is pro graded.
75:11 pro graded about four kilometers into the . Okay. But you don't see
75:15 breaks the deposition here. It's all reef rock. The only thing that's
75:20 is gonna as you pro grade and . Okay. So the question
75:27 where do these timelines go? How they go through the reef?
75:32 it depends on how you interpret the . Right? How shallow or how
75:35 was this reef? I think that's of the story. And so does
75:39 come like this and dive down or straight across into the basin or does
75:44 come up to reflect topography and dive down into the force load. That's
75:50 you have to struggle with. Because you don't know, you can't
75:53 where those, where that small scale tie back in to this more massive
75:59 . Okay. And of course you never know how anything ties to the
76:03 four slope and basin out in front the right. Okay. Everybody appreciate
76:08 I'm saying And turn this around. . If you didn't know anything about
76:12 regional setting and you punched a core you encountered a bunch of rocks that
76:17 like this right? With all this scale cyclist city at least you
76:21 now this is probably platform material, ? You're not going to do this
76:25 the margin and you're not going to it for sure in deeper water.
76:30 , so you can use sometimes the of cyclist city to help you start
76:34 your gross de positional setting until you some more wells. Okay,
76:42 let's contrast that with the ramp Okay, I think you can appreciate
76:47 the lower slope angle carbonate ramp shown in orange has the ability to
76:52 out into the basin, right? depending on where your high energy faces
76:59 , those faces are gonna track that gradation all nature. And then what's
77:03 happen is sea level is going to , you're going to increase sea
77:07 That's gonna shut down your high energy . You're gonna drown it out.
77:12 gonna do what we call back you're going to shift the focus of
77:16 water deposition. Somewhere up dip. , you're gonna start the machine back
77:21 again when things are really great and gonna build up and build out back
77:29 up build pro grade, okay. geometry, you see there is classical
77:36 rotational geometry associated with the ramp And you can see from a reservoir
77:43 standpoint, right? If your orange the reservoir, the green is deep
77:47 carbonate, you're creating strata, graphic , right? You're entrapping the prophecy
77:53 that deep water carbonate. Okay. you're also doing what you're stacking potentially
78:03 reservoirs on top of each other. theoretically could be accessed by one?
78:09 . Okay, that's the beauty of ramp model. Okay. You see
78:15 ? Alright, But you have to the right position, right? So
78:19 no there's no panacea here. It where the right position is. So
78:25 you're too far down dip, obviously water, you're never going to see
78:28 kind of cyclist city. Right? the same thing is if you're further
78:31 dip, you're not gonna see that well. But if you could find
78:35 magical interplay between the stuff pro grading the basin and back stepping. Pro
78:40 back stepping programming. And this creates incredibly beneficial scenario for multiple stack reservoir
78:50 , right? With good strata, trapping and if the green is also
78:54 source rock, your locally just juxtaposing your source to your reservoir.
79:02 So have you ever wondered why the have the incredible Jurassic reservoirs they
79:09 It's just for this reason right Okay, your body is associated with
79:17 big fields like dewar and Qatif. Our rap related carbonates, right?
79:25 so called shelf stuff here is really ramp. All right. And you
79:30 how it builds out and then sea comes up to terminated. The Hanifa
79:35 the basis on faces, which is the source rock. It has up
79:39 13% T. O. C. it's a world class source rock and
79:43 what happens with that deepening you shut your rap, You shift your focus
79:47 shallow water deposition somewhere up dip, starts back up again, builds
79:53 pro grades out, gets drowned back , pro grades out multiple stacked reservoir
80:01 . And then what's the other part the story for for go are it's
80:05 big dome, a structure like I you on cutter for that one
80:09 Right. Big anne klein with 1500 of closure. Right? So the
80:15 is 1500 ft thick. Anything that porosity in that trap produces hydrocarbons.
80:24 , and then how long is this ? Um Guar is like driving from
80:30 to austin 150 miles. Okay, you can see why the Saudis have
80:36 so much hydrocarbon. Right? Even people think they are actually lying about
80:41 , they think they've actually run out a lot of, a lot of
80:44 oil. But but they've been saying for a long time too. So
80:50 see. Alright, everybody appreciate the relationship between the two end member models
80:57 the and the and the so called relationships associated with the cyclist city.
81:02 want to be thinking in those if you have some idea of your
81:07 fizzy graphic setting, right? Whether more platform to basin or whether it's
81:11 ramp to base in transition. so having said that, let me
81:16 a wrench in this whole discussion here by clouding the issue a little bit
81:21 make you aware of the fact that major storm activity can mislead you and
81:30 an artifact of what looks like cyclist . That has nothing to do with
81:34 . The like I've been talking Right? This is cyclist E driven
81:38 these relative changes at sea level, ? Sea level change provides the
81:43 You fill it up and then you it by another change in sea
81:47 Right, But let me throw a here by bringing you back to the
81:52 cock that we started with. Remember quarry with the with the layers the
81:59 cyclist city. So, let me first by just showing you the deposition
82:04 for the in southwestern Germany, it's ramp model again that deepens to the
82:11 comes off of land. You've got ramp crest would be right in through
82:15 where you get the and scalable grain . Okay, with the restricted lagoon
82:23 it, And then you gradually deepen deeper water up to the northwest.
82:28 , And if you look at this cross sectional view, this is what
82:31 would see. All right, there's the ramp crest right here.
82:37 , and that's the factory for making IDs and scalable material. All
82:43 And then look what's mapped out here deeper water. See those lines,
82:48 horizontal lines that extend from green to . Those are what the Germans map
82:54 tempest tights. These are storm Okay, and the neat thing about
83:01 Germany is every little town has its quarry for building stone. So that
83:06 that I showed you earlier right, used for building stone principally. But
83:11 can you can uh what that means every little town, which is these
83:16 are really closely spaced or just a , so apart from each other.
83:21 that means is you can actually trace betting styles from one quarry to the
83:24 quarter to the next quarry. And what Tom Wagner did for his dissertation
83:29 he was able to demonstrate that these tights actually tie back to the ramp
83:36 . Right? The source. He's able to show that these things
83:40 regional extension that they extend out into basis, sometimes up to 40
83:46 Okay, so it's actually easier to this on a low relief ramp.
83:51 ? If you had a steeper you would do what you would
83:55 you bypass and then shoot it Right? But here is continuous because
83:59 a lower slope angle and this you could physically trace this stuff out
84:04 the deeper water setting. All And so the point I'm trying to
84:08 here is if you go out in deeper water setting out of context and
84:12 look at these tempest tight layers. , shown by the light green surrounded
84:18 black. The black would represent the , deep water based on sediment punctuated
84:23 the green. Right? The tempest . If you look at these out
84:27 context you say, oh, that's cyclists. The wright. I'm in
84:31 shallow water. More platform interior No, these are not even
84:37 Okay. Because you're not seeing an showing character. You're seeing you're going
84:42 what looks like really deep water sediment by black boom into a grain
84:49 So you're missing that intervening faces, ? You should where you should gradually
84:54 . See what I'm saying. See this is not cyclist city. The
84:57 we defined it. These are not showing sequences because you don't see that
85:02 showing effect. But out of people would take this to be sick
85:08 . E Alright, these are storm that get shot out into the
85:13 This is how these ramp carbonates program the Sholes pro grade they shoot stuff
85:20 as a pro grade. Okay, gonna see this in a minute.
85:24 right. You understand what I'm No, just shallowing That just means
85:34 it's shallower as you go up. , believe it or not, you're
85:41 first person ever to ask what that because nobody's ever asked. I don't
85:46 think about it. So yeah, that I think that's just showing the
85:50 up. Right? Usually when people it like that, that means shallow
85:55 . They turn it around. It deepening up which is not very common
85:58 carbonates. Okay, Alright everybody you what I'm saying? So you have
86:04 be a little careful here. Especially ramps successions that what you see may
86:09 be a true representation of deposition and city may be an artifact of the
86:14 deposits. Okay, so here's a world example in the subsurface. These
86:22 Jurassic age, carbonates from east texas part of a gas field trend in
86:26 texas. We're gonna talk about this a play type next weekend, but
86:31 want you to appreciate you see the here. This is what we call
86:34 density log that we use to map and then a gamma ray log and
86:40 rays usually used to map the amount clay or our delicious material or organic
86:46 material in the in the rock. this whole interval is completely cord.
86:56 , and so my descriptions here are on core core descriptions, right?
87:01 not based on a few thin sections anything like that. So and then
87:05 highlighted anything with greater than 5% ferocity blue and all the processes gas
87:12 Okay. And if you took this of context and people have done
87:17 they think these are multiple. Let just say these are the blue is
87:21 productive from Hewlett grain stone. And so the the idea was that
87:28 are just multiple stack. Do it right then. Built up through
87:32 but again they're surrounded by the same , deep water, deep ramps
87:37 you don't see the gradual shoaling, don't see the active and stable
87:42 right? That every body system You just go from deep water boom
87:47 into it looks like high energy grain and then boom back into deeper
87:52 This is just punctuation by the storm . There's only one real shoal here
87:58 that's up here. Okay. And show you this rock data next
88:02 So you can appreciate you'll see the again, I think. And this
88:08 the only show in the system. right, these are all tempest sites
88:12 sand, Okay, that are pro out in front of this program.
88:17 shoal. Okay, so you would right, active shoal stays in a
88:25 of active agitation, right? It's to preserve a high degree of the
88:30 right? Every day. You've got strong tidal current agitation, you've got
88:34 great frequency wind wave agitation, very to burrow that stuff. So you
88:39 preserve a lot of it. But happens when you take a tempest tight
88:45 shallow water and you pump it down deeper water initially. It's going to
88:49 stratified right, when you lay down the storms. But then what's gonna
88:54 is gonna sit there in deeper it's not moving anymore. So what's
88:59 to happen, It's gonna get Okay, So if that's true,
89:05 I should be able to show you I will next weekend that there's a
89:09 degree of preserve stratification in this system . But never any preserve stratification.
89:15 of these sand bodies here because they're shut into deeper water. Okay,
89:20 here's one of the contacts in There's the down ramp, but he
89:26 . All right, that's the background . Here's one of the tempest
89:30 Again, sometimes these things are a feet thick. Sometimes they're up to
89:34 ft thick. Probably not one Probably multiple events. But look at
89:39 internal stratification. There is none. . It's all reworked. In
89:44 the contact is reworked. It probably sharp when that was initially laid
89:49 but then everything just sits there and , deeper water. It gets reworked
89:53 borrowers. Okay. But this stuff still a grain. Stone still has
89:57 same kind of ferocity development. All . So everybody appreciate the caveat
90:04 So, this is a challenge for That carbonates. Right. Were we
90:08 we work up the core. We work from the bottom up.
90:13 are we thinking about? We're thinking upward shoaling. Right, But what
90:17 we have to always be concerned about coming in from the sides too.
90:23 . There could always be a chance move stuff from another environment into that
90:27 that you're looking at. Okay. , so let's finish up these are
90:33 controls. I hope you appreciate the between carbonates and classics. Now the
90:39 setting is the dominant control because that what kinds of faces you developed and
90:44 much sediment is produced that obviously controls thickness. Nobody argues relative sea level
90:51 important for terminating these packages for providing accommodation. But you always should look
90:59 it in terms of the in terms the relative sea level change, incorporating
91:06 three components. They're used to see and tectonics and then appreciate. You
91:13 have to change sea level to terminate carbonate succession. You can have tectonic
91:19 in the in the inner land and bringing classics in to that carbonate environment
91:27 that achieves the same purpose. You cloud up the water, choke
91:31 filter feeding mechanisms of these organisms. done. Okay. So don't assume
91:37 change and every termination of a package to be do necessarily to sea level
91:43 . And then with respect to Again, it's the same relationship.
91:47 can do this by either a relatively rise in sea level, which is
91:52 story for like Western Canada, which a highly society basin or you can
91:57 sea level first, which is the for the Pleistocene. We always dropped
92:01 level first and then we re flood start the next phase. Or
92:06 there could be no sea level change all. It could be influx of
92:09 setup. Okay. And then I've the internal geometry typically pro gradation als
92:17 not always. But when it that's walter's law. When it's not
92:23 because sea levels rising too quickly or hole is too deep to pro grade
92:30 . And so that forces you into other style of internal geometry called aggregation
92:37 geometry. Okay, so sometimes we that and carbonates now where I want
92:42 finish up is the de positional styles geometry styles between cycles. This is
92:50 creates what people used to define the called stacking geometries that we started with
92:56 were the basis for the systems tracks Exxon uses right to try to infer
93:02 position on the sea level curve. these are the four types. This
93:07 was all documented by winning Stokes first in their work for the western Canadian
93:14 and then picked up by Exxon. they tried to fit this into their
93:19 . Tracks approach. Okay, so me show cartoons that illustrate this.
93:26 back stepping. All of this is on Western Canada. The blue represents
93:32 shallow water carbonate platform and near the for each of these cycles of sedimentation
93:38 a reef. Okay, so the cycle and the and the dark green
93:44 the deep water basin on carbonate. , so in the first cycle,
93:48 reef margin builds out to this position here, then sea level comes up
93:53 terminates it. We shift our focus shallow water carbonate deposition somewhere up,
93:59 . We build back up the sea . We pro grade out but the
94:01 only programs out to this position right . And then the next cycle,
94:06 only pro grades too right there. the reef is the primary reservoir.
94:11 ? So if you if you track reef reservoir, what is it doing
94:15 time? It's stepping back. So what do we call that?
94:21 back stepping. Okay. Everybody see each successive cycle the reef is stepping
94:27 . Okay. And you're gonna see next weekend that these major cycle contacts
94:33 by the X are also vertical permeability . We talked a little bit about
94:39 this is last week when we get solution and calcite sanitation. But you
94:44 get a faces change sometimes that creates permeability barrier. Right? So you
94:50 the implications for modeling here for for a reservoir, right? You would
94:56 to drill a well here and a here and well here in order to
95:03 all the oil and gas out of three cycles. Okay, This is
95:08 they didn't realize, right? They they thought these reefs were inverted buckets
95:13 ? Where you just put a well the top and suck it all
95:16 They didn't realize that there's the graphic cyclist city associated with these
95:21 Okay. And that controls the distribution the reservoir quality retreating is like back
95:28 . But you don't shift back very . There's still some overlap between one
95:33 shown in the blue and one on . So theoretically one. Well could
95:39 access these two reef and ferocity Okay, this is the least common
95:45 the four types and then up This is pretty common where you get
95:54 platform systems facing open ocean and facing wind, relatively deep water offshore.
96:03 can't pro grade but to a certain . So the first cycle builds out
96:08 this position right here, terminated the step, your shell water carbonated and
96:15 back up and you pro grade back to this position. But basically you
96:20 go any further than the previous Can't go any further than the previous
96:24 . So what's happening here? Everything stacking basically one on top of the
96:28 in the same position. That's what called up building or you could use
96:33 term up stepping or you could use term aggregation and stacking geometry.
96:41 And then the last procreation. All successive cycle builds out further than the
96:46 cycle. This is the kind of we normally see off the leeward sides
96:51 platforms or where we have ramp related , right, lower slope angle.
96:57 see these things jump out from cycle cycle. Okay. You can see
97:02 strategy again, you know with this . Well could access three reservoir units
97:09 this. You again we need to here need to drill here, drill
97:13 . Okay, I really appreciate the . And I'm gonna next weekend.
97:19 is already post this. This will posted on your trying to think of
97:25 posting yet or not. But I'll you some cross sections from some of
97:30 Devonian stuff. So you can see detail that goes into these cross sections
97:34 we'll talk about some of that next . So you can see the strategies
97:38 they had to think about to fully some of these reservoirs. Okay,
97:44 . So let me just finish up a couple of examples here and we'll
97:47 another short break. First example of lake. This is limestone,
97:53 Western Canada Reservoir simple cartoon here, the cycles. So 1234 cycles of
98:01 . The black lines represent the major contacts for regional correlation. The blue
98:08 the reef related faces that have the reservoir quality. So, let's start
98:13 this cycle here. The oldest the internal geometry is building up and
98:19 . So what do we call We call that? Pro gradation.
98:22 internal geometry. Okay, and then do we call the geometry from this
98:28 this? You stepped out, No, back step will be the
98:41 way. So it's four stepping or gradation. All right, wasn't
98:48 This right. That's the fourth step . Okay, so you stepped out
98:55 the previous cycle and then now you're step right, next cycle, back
99:00 this way further back. Right. the strategies that are needed now for
99:07 the reservoir, you've got to drill different, you know, maybe you
99:11 overlap a little bit with some of wells here to access both, but
99:14 going to require separate. Well that's to require separate well for production.
99:20 , so that's the 300 million barrel field norman wells, I'm sorry red
99:27 is 1.3 billion barrel oil field. is one of these atoll reef
99:32 I showed you the modern analog yesterday Belize and Australia. Remember those atoll
99:38 complexes up on drown carbonate platform? the modern analog for something like
99:44 And I mean, look at the here, that's only half a
99:48 So, you know, these are a few miles across for scale.
99:53 is a schematic cartoon, you're gonna the details in the next lecture for
99:58 water. But basically, what is water doing through time? It's back
100:03 itself out of existence. Right? successive cycle is running out of space
100:08 eventually it's gone. Okay, But can see again the strategy, you
100:14 need to develop that kind of Alright. And then the last example
100:20 norman wells, norman wells is the carbonate reservoir in Western Canada and discovered
100:27 1920 but almost went online at the of World War Two, it's so
100:35 that there was no infrastructure to get online. They were going to build
100:40 infrastructure during World War Two, but war ended. And so s.
100:45 put that off for another 25 So it really wasn't until the seventies
100:50 eighties when they started to develop this . All right. And what was
100:54 model? The model was Atoll reef , Right. Reef margin going like
101:00 . Right. They thought the reef all one unit all connected,
101:06 They thought they could just put a in and suck it all out.
101:11 course, that busted, Right, they didn't realize the reef margin is
101:16 up of a series of stack Okay. In fact, here's the
101:20 already seen this diagram. This is simple cartoon for norman wells. I'm
101:27 give you a detailed cross section 630 million barrel oil field. And
101:35 the production? The production is from reef flat and brief margin, light
101:42 and orange, and some of the . Okay, and look at the
101:48 here, that's only 3.5 kilometers across scale. Alright, so, let's
101:53 look at the stacking geometries from cycle cycle. What would we call this
101:59 this side? With the overall effect ? From cycle to cycle.
102:08 you're building up building, right. . Just building vertical from cycle to
102:13 , you could argue. Maybe this that retreating style? That least common
102:18 shift back a little bit, but in continuity. But the sense you
102:22 here is everything is pretty much stacking the same place, right? That's
102:26 we mean by up building or All stacking geometry. And then over
102:34 , what's the overall sense? Back ? Right. Everything's shifting back from
102:43 to cycle. All right. So let's put on our exon sequence.
102:49 adds. Alright. So let me your memory here when you have you've
102:57 out of a low stand of sea and sea levels rapidly rising.
103:01 That's the transgressive systems track. What your system tracks. Do What should
103:09 packages within that system track? Do should back step. Right. The
103:14 levels rising rapidly. Alright, so stepping would be transgressive systems track.
103:21 ? That's how Exxon would interpret that of the of the build up.
103:25 right. And then see double stabilizes ? The change from back stepping two
103:35 building is where they put the maximum surface. Alright. They're saying we've
103:41 now we've got this hole to fill . Okay, what are we going
103:45 do? We're going to catch up sea level. We're gonna go
103:50 That's the early high stand. So would call this Oh wait a
103:55 This is the early high stand, , Because it's up building on this
104:00 . And then if they saw things grade, they call that the late
104:03 stand. And they would say think was starting to fall again as it
104:07 back down the drop for another low . Okay. You see the problem
104:13 ? On the one hand, they tell you? Sea levels rapidly rising
104:17 here to explain this stacking geometry. wait a minute, no sea level
104:23 rising. We're catching up right early stand over here. Which is
104:30 It's neither this is the folly of whole approach. Okay, so you
104:38 tell me sea level is changing like from one side to the other.
104:43 3.5 kilometers. I mean, see I'm saying, That doesn't make any
104:52 . So there's something else going on that has to be more controlled by
104:56 environmental setting. So, again, , what's one of the first questions
105:01 always wanna ask? Whenever you look a carbonate platform of carbonate building?
105:11 am I paleo geographically right. On global scale? Where was I relative
105:17 the paleo equator? Right. And what comes along with that? The
105:24 winds? Right. So when word leeward, right, you want to
105:28 that and you want to know how the winds were. Okay. And
105:34 you don't know the paleo geography But during the Devonian, Mhm.
105:39 would have been about 15 degrees south the equator. That puts you into
105:43 heart of the strong easterly trade winds . Okay, that means the winds
105:49 have been coming from the right to left. Okay. Windward leeward,
105:56 did I show you yesterday in the trade wind belt on keiko's platform,
106:00 did we get most of the shedding the carbonate sand? Windward or
106:11 You guys have a lot of reviewing do? Okay, so,
106:16 leeward. Right. Didn't we shut everything got pushed to the leeward
106:22 Remember west spit on keiko's platform at end of Ambergris stuff gets pushed down
106:27 the edge, goes over the hurricane pushes it over, renews,
106:32 pushes it over. Okay, so at what are the four soap sands
106:37 , the debris sheets shed from the . Where are there more for
106:41 And this side? Not this Right. Isn't that consistent with this
106:49 a leeward margin and stronger trade winds not only mud and silt sized
106:55 they bring the scan the sands with . Okay, so the sands are
107:00 up by hurricanes. Okay. And of that hurricane activity obviously sheds
107:06 but once the reef is broken this is where the trade winds come
107:10 play to push that stuff off. leeward margin. Okay, but I
107:15 that. Alright, so the fact you've got greater degree of shedding more
107:22 soap sands on this side compared to side that's consistent with the leeward versus
107:28 Wynwood? I told you yesterday that word margins tend not to shed a
107:32 of material and I'm gonna prove this you in a minute. Alright.
107:36 next lecture, but okay, these really important concepts that you need
107:42 you need to appreciate. Alright, you were carbonates, right? I
107:49 you understand now. The first question of the box should always be,
107:53 my fizzy graphic setting? Two scales ? Global, where I sit relative
108:00 the equator. So it's a tropical and what were the strength of the
108:04 winds? And then the second question be, what's the local fizzy graphic
108:10 ? Is it more platform to basin more ramp to basin? Because that
108:14 have some influence on how easily do move some of the stuff from shallow
108:18 deep? Okay. We're gonna keep on this. Alright, because obviously
108:26 setting you up for a discussion next where I'm going to apply just about
108:31 . We've talked about these 1st 1st weekends too, exploring for reservoirs or
108:37 reservoirs. Yes. Okay. And that's what we're gonna try to talk
108:47 next weekend. Alright. I think the last, not the last
108:52 Okay. Here, this is good this finishes up on a more on
108:56 bigger scale, just to show you stacking geometries can be expressed in a
109:03 wide scale. All right, this a data from the Bahamas during the
109:09 cretaceous. Alright. And I'm gonna gonna show you this in more detail
109:14 . But look at this relationship this is a carbonate platform in the
109:20 . Alright, older than what we at in the modern. And then
109:23 another platform over here. So there's deep water and payment. And so
109:27 can see the seismic interpretation here. . And look at the filling.
109:33 not symmetrical, right? It doesn't equally from both sides. So you
109:38 to guess orientation with respect to the . Windward side would be which way
109:46 the right. Yeah. Yeah. this platform was this is the leeward
109:54 to this platform. It's gonna push off preferentially that margin. And then
109:59 is a windward facing another platform. has been postulated. Not drilled
110:05 but this is the side you get reef. But what you whether you
110:09 re for grain stones, what don't get a lot of here shedding?
110:14 . And that's the point. I want to appreciate when we're facing
110:19 open ocean facing margins tend not to a lot of material into deeper
110:23 They tend to have it thrown back onto the platform to make the brief
110:28 or or some other kind of carbonate system. Okay, It's the leeward
110:34 where you shut and then this side this diagram on the right is from
110:39 Canada Devonian again. And this just shows you two of the stacking
110:46 We just talked about and why you the difference depending on what side of
110:50 base. And you're at all? ? So the prevailing wind direction again
110:53 out of the eastern quadrant. So do the reefs occur on the windward
110:58 side? Right. And look at cycles reef cycles. That back
111:03 Right. That's on the windward There's no reef deposition on this side
111:07 it's the wrong orientation. These are series of ramp carbonates. And what
111:12 they do? They pro grade. . The trade winds are pushing this
111:16 off from shallow to deep and so this side, you get a strong
111:21 predation. All geometry here, you a back stepping geometry. I
111:26 again, when he put this gave this talk at a P.
111:30 . To make this point, Because, Exxon would say that's a
111:34 falling sea level, right there. the late high stand to create the
111:39 . Additional stacking geometry. But then would turn around and say no,
111:43 rising sea level. That's the transgressive track. And that makes absolutely no
111:48 . Again, over a distance of ? 30 miles? 40 miles.
111:53 no way. Okay, so, know, sea levels and I'm not
112:00 sea level. I am downplaying sea as a driver for carbonate deposition provides
112:08 accommodation terminates. But how you fill the whole depends on your local environmental
112:14 . Okay, Alright. I think it. Let's take a let's start
112:24 at 3 20. Alright. In eight minutes or so. Okay.
112:37 last two lectures today are on log expression of carbonates and seismic expression
112:46 carbonates and I lump them together as 13 and 14 on blackboard. So
112:53 start first with the log stuff and go through this and take a little
112:57 and then we'll finish up with the expression of carbonates just to give you
113:02 little bit of flavor for how sometimes well dogs can be used for breaking
113:09 some of these deposition packages. Of , those of you that uh end
113:15 working in industry or working in industry now, you know that the log
113:21 tools are primary method for correlation, ? People run the well logs and
113:27 try to correlate resistive itty or they to correlate gamma ray or they try
113:30 correlate some other log uh logging tools well to well, and that's how
113:37 try to establish some some sort of strategic graffiti and try to understand maybe
113:43 regional setting. And you know, say you probably can do this a
113:47 easier in the world of classics, ? Because you can sort of tell
113:52 from sand court sand on, on log. But carbonates is a little
113:58 . Alright, there's no panacea here breaking out mythology for carbonates. And
114:04 if you could break out the mythology still doesn't mean anything in terms of
114:09 , right? Because remember we're trying correlate environments of deposition or faces from
114:15 well to the act to the next order to establish a regional picture about
114:20 going on. So we're gonna do little exercise here in a minute.
114:24 let me just start out with this slide here talking about the qualitative use
114:29 logs and carbonate sequences. Sometimes we use these for discerning and correlating time
114:35 de positional sequences and sometimes for recognizing deposition all faces. But this is
114:43 dependent on what rock data. You've got a ground truth through log
114:49 with rock data. You just can't around that and carbonates, right?
114:54 you know, some people pretend you but that's that's just not true.
114:58 right. And the best way to your log responses to calibrate it against
115:04 data. Right? Of course A of companies don't want to core because
115:08 don't want to spend the money for time it takes to core.
115:12 but core is the optimum database because see color, you see sedimentary
115:19 You see contact relationships. You see larger fossil fragments and things like that
115:24 help you interpret the environment of If you don't have core, you
115:29 still do a lot by looking at side wall or percussion cores. They're
115:35 with that technology where they put a down and they shoot into the side
115:39 the well bore and pull out a chunk of rock to look at.
115:43 that's useful and that's better than the cuttings. Right? The when the
115:49 bit grinds up the rock, they those cuttings every five or 10 or
115:53 or 30 or 60 ft. And if you recover the well cuttings closer
116:01 like five or 10 ft, you do a lot with those cuttings to
116:04 to piece together some understanding what's going . Okay. That's the first part
116:10 the story. Right? And the part of the thing that is a
116:14 of a problem here is we're always about the dye, genetic over print
116:20 genesis can bugger up your log response mislead you. So you need to
116:25 what kind of digest history you're dealing . You're only going to get that
116:29 the rock data by looking at the within sections and verifying composition,
116:36 poor types and by implication what the is. And then listed the quality
116:42 the log here. What I mean , you know, we have access
116:47 have access to more mature basins where databases were principally the old resistive
116:53 And uh sp logs. Right today have more modern log sweets, better
117:00 logs, we have pe curve logs tell us with ology and we have
117:07 just you know, gamma ray logs ? Or spectral gamma ray logs that
117:12 us understand what the gamma ray is to. So that's what I mean
117:16 the quality of the log. And de positional setting. This is the
117:21 consideration when you're trying to correlate from to, well you need to have
117:25 idea of your general or at least deposition environment. Right? And hopefully
117:31 get that from your regional data from seismic or something like that.
117:35 Trying to correlate across the platform by to correlate, you know, from
117:39 to basin ramp to basin. That's need to know that and you
117:44 you're not going to figure that out one well bore. But hopefully you
117:47 some seismic data or something like That helps you. Alright, so
117:51 do a little exercise here. We've these five chord wells from the Devonian
117:57 western Canada, you can see one here and you can see the scale
118:02 the right 25 m. Everything dated top of a regionally extensive tidal flat
118:09 the four million and hydrate, right diatoms are ideal especially when they're
118:17 Right? You want this flat of as you can get when you try
118:20 correlate and try to hang your section from well to well, so that's
118:26 good bottom datum. The log suite is gamma ray on the left and
118:33 density log on the right. And if I ask you to correlate
118:39 well to well, again, I tell you how widely spaced these
118:43 but I can tell you that, know, these are miles apart.
118:46 is not part of a reservoir This is a regional exploration effort.
118:51 to get a feel for the regional of some of these carbonates.
118:55 if you're going to correlate from well well, what's what's the first assumption
119:00 probably make here? The cleaner intervals , right, are not just
119:10 but shallow water carbonate. Right? usually what does the gamma ray usually
119:19 to response to our Galatians material or material? And where are you likely
119:23 incorporate that? Usually in deeper Not shallow water. Okay, so
119:29 cleaner carbonate, historically, most, industry people would do what they would
119:34 this as a shallow water carbonate And you see where it kicks off
119:38 the right here kicks off to the , that would be a return to
119:42 deeper water, shale or highly are limestone. Okay. And then if
119:49 ask to correlate from well to what would you guys do? How
119:55 you tie from well to well, would you look at, Robbie?
120:08 , right. Here, the gamma , I think most people would would
120:13 on the gamma and they would run here to hear to hear to
120:20 And then where would you go? a little bit different response for
120:25 Well, but you can you can it's trending to a Shelly succession.
120:29 somewhere bringing in somewhere here. And the interpretation would be well,
120:33 is all shallow water carbonate. Give us the carbonate seminar. So
120:38 not talking about classics. Okay. yeah, I'm gonna come up with
120:44 interpretation like this. Alright, broad water carbonate platform dropping off into deeper
120:50 basin, deeper waters allowing you to some articulation material and that's why you
120:56 the ratty gamma ray right there. . And you can see they actually
121:03 off of this right? They drilled of that model where they played for
121:06 platform margin and they found hydrocarbons. . But each of these wells is
121:14 cord Okay and actually this is not right answer. The right answer comes
121:20 the rock data and this is the answer. It's actually parts of two
121:26 platforms. The main carbonate platforms off the left. Okay. And then
121:32 they drilled was actually a satellite offshore carbonate platform. So I think like
121:39 example many example of the Bahamas, little small carbonate platform surrounded by deeper
121:47 . Okay and how did they know ? They knew that by looking at
121:51 rock data for these other wells right , deployable sands that we talked about
121:57 norman wells, here's the basic carbonate what's the lesson to be learned here
122:03 on carbonates can read clean right mentality a lot of people is that all
122:08 deep water carbonates read dirty on the that's not sure. So here they
122:18 this up with the help of four or just build on the log this
122:22 data. Gr data. This is core data based on the log.
122:28 were not able to do so. . No, you would never be
122:31 to resolve this kind of variability on log. There's no way. All
122:37 . That's why that's why people came with an interpretation like this.
122:42 They just assumed the clean, clean on Gamma is shallow water platform.
122:49 right. Anything that's more ratty with our delicious material is deeper water.
122:55 . But when you look at the data, I said every one of
122:58 core dwells, every one of these is entirely alright. The core data
123:04 you this relationship here. So first to be learned is that gamma ray
123:10 read clean and deeper water settings. right. So think about some of
123:16 chalk deposits around the world. They read pretty clean on the gamma and
123:22 the four slope stuff right, reads , but it's not in place.
123:26 is in place. The blue but displays carbonates are yellow. Okay?
123:32 then look at where the shedding Most of the shedding, you know
123:35 you know, for the Devonian. , you know, the winds are
123:38 out of the eastern quadrant. So this platform was windward on that
123:43 . But leeward on this side and be more shedding off of this
123:47 Right here. Okay. And not much shutting off the when we're facing
123:52 of both of these platforms, but can see what they missed here.
123:56 . They would have encountered porous four sand in this. Well, right
124:01 , but no one hydrocarbon because there's trap. Right? Where's your
124:05 Your trap is up against the So you see what this changes the
124:09 story here. You've got potential to this entrapment relationship right here. Uh
124:16 drilled up on the platform, They could potentially step out and drill
124:20 of the margin here and they drilled on the platform back here. They
124:24 step out and drill the margin Right? So it changes the whole
124:28 . If you understand the faces Alright. You're never gonna get the
124:33 relationships just from log response. There's just no way. Okay. And
124:40 the goal here always is to try incorporate whatever kind of rock data you
124:44 get your hands on core, the side wall or percussion cores. Next
124:51 well cuttings, you can do a with. All right. And so
124:55 always want to start with the rock and break out as best you can
124:59 these relationships and then tie that back the log response. Okay? And
125:06 if there's a faces relationship between log and and the the logs.
125:14 Faces in the logs And I've seen go a step further and get into
125:19 evaluation where they they've identified a relationship their cord. Well, right.
125:25 see that some of these faces have unique log signature. They've crossed a
125:29 of different log parameters and they've established relationship and then they try to take
125:35 to the next well where they don't any rock data and sometimes that works
125:39 well. Okay. But as you've , things can change laterally.
125:44 So, you know, that's always risk. And then the other risk
125:48 whether the die genesis buggers up some that, some of that log
125:54 Okay? But you know, this what makes carbonates unique. You can't
125:59 can't just work the well locks even companies do this over and over and
126:03 again. You do what you you what you can with you do the
126:09 you can with what you got. basically but all of you are faced
126:14 right that work for companies right. what you can but you have to
126:19 the limitations to that approach. All . And that's what I'm trying to
126:22 here. Right. If you can some rock data, you're going to
126:26 a better understanding and maybe you're gonna , provide yourself with some new opportunities
126:32 chase in terms of where you might the hydrocarbon. Okay. Okay.
126:38 a couple of general rules of thumb with respect to well, logs and
126:42 cyclist city. Sometimes the sp gamma marks a major cycle contacts and sometimes
126:50 piracy logs track these upper showing, me, track these upper chilling of
126:58 that we've been talking about. I'm show you some examples where we can
127:05 that, but I'm gonna show you copy out here because first of
127:09 when you're trying to correlate, you to think in terms of your fizzy
127:12 setting and you have to be concerned the die genesis, especially with respect
127:17 the proxy logs. Right? If playing density or neutron logs, sonic
127:24 , you've got to be concerned about dia genesis that could bugger up some
127:28 these porosity relationships and that could mislead when you're trying to correlate from well
127:33 well, okay, so what I'm do here is I'm going to share
127:37 you some summary slides that were given me by my colleagues winning Stopes,
127:44 friends and colleagues that I've worked with and on for a long time.
127:49 this is a summary of their experience Western Canada for the different locks sweets
127:56 to different fizzy graphic settings in both Devonian and Mississippian, but I'm not
128:02 going to show their examples. I'm to bring in examples from other sequences
128:07 different ages. Okay, so it's just gonna be devonian mississippian.
128:12 so we're going to start first with general setting where we have shallow water
128:17 or we have platforms with reef related along the margin. Okay. And
128:23 this is a summary of their success these different log sweets to try to
128:29 out some of these upward shoaling right. For correlation from well to
128:34 . And the first thing that doesn't very good is the gamma ray log
128:39 you're an overall shallow water setting. it's very hard to incorporate a large
128:44 of our delicious or carbonaceous material. , uh receptivity logs they found not
128:52 be a very good use. Where they had more success were either
128:58 the sp log with these older log . Alright, react reacting to
129:05 which is probably reacting to porosity. . And then they also obviously found
129:10 process logs to be useful for picking these upper trillion sequences. Because what
129:16 is you shallow up? What have seen? Where's your low energy MMA
129:20 carbonates always at the base of the . Right. And you start shallowing
129:24 that improves your ability to do what get into a higher energy setting where
129:29 can develop a better amount of primary . Right? With better permeability.
129:36 that doesn't mean that's always going to right at the top of the upper
129:40 sequence but it's going to be towards top. Right. And it's certainly
129:44 going to be at the base. . If you're playing a limestone that
129:48 been digested cle altered. Okay, the proxy logs nicely tracked this.
129:54 ? You'll see the process the increase , decreases the cycle contacts increase upward
129:59 at the cycle contact. Okay, go through some examples here. This
130:06 examples from the cretaceous in texas. is a sequence south texas it did
130:12 produce but produces oil and gas and parts of the gulf rim. We'll
130:17 about this play type later next What are we dealing with here?
130:23 p curve on the left and then data and prosperity and perm worked out
130:30 core plug analysis. All right. look at the date of this
130:34 1976. Alright, and this is way you don't want to do this
130:40 anymore. Right. These are not . These are little with ology is
130:47 . This is like litas photography. again, what does that mean?
130:52 an environmental standpoint? Right. You could relate to what a build
130:57 I guess. Right. But what your grain stones? Are they dr
131:03 stones and they in situ Olynyk sands something else? Right. And what
131:09 the pack stones and wacky stones, they related to deeper subtitles, shallow
131:14 tidal flat and see what I Right. So, this is the
131:18 you don't want to do things Excuse me. This is the way
131:26 think you want to do things. . This is my modified uh example
131:36 from that same sequence. Okay, are cores that I that I use
131:41 Houston when I train. Excuse Mhm. When I when I do
131:51 courses where I have a core When I do in person courses,
131:55 have core exercise and this is some the chords that I use for my
132:00 exercise. So I've reinterpreted locke's uh . I put it into an environmental
132:08 . So let's just here's the log . Okay, C. B.
132:14 cycle contact. Okay, let's start the base. What do we have
132:20 the base in orange? We have deeper subtitle these democratic wacky stones and
132:24 stones with some pelagic micro fossil But not a lot. Okay so
132:31 not a true deep water basin because not dominated by that fabric. And
132:36 that grades up into a shoal complex . The blue would be active shoulder
132:42 would be stabilized. But most of uh these these sands are not politic
132:47 skeleton. Okay. And then you the bottom, there's a change
132:54 There's a deepening. You go from active show back into this deeper
132:59 Okay, so I flagged that as cycle contact and look how the
133:03 P. Log picks that up. ? You get a deflection back toward
133:07 shale line. Okay? It doesn't all the way back to the shale
133:11 because that's not shale. Right? is that reflecting, reflecting a change
133:16 permeability where you go from porous and active shoal into a deeper water subtitle
133:23 . Okay. And so that starts new cycle and again you would link
133:28 greenback to a stabilized shoal because what you shallow back up to you?
133:32 back up to another grain stone active . But now it's not skeletal,
133:38 skeletal analytic. You're starting to mix types. Right? And the fact
133:43 you're getting new analytic means what? persistent agitation. Right, So that's
133:51 reflection of the overall shoaling from one to the other. And then you
133:56 the same thing again and you start cycle here. Right, See the
134:01 here shows that partial deflection back on S. P. Log. And
134:06 you start a new cycle of sedimentation goes again from stabilized shoal to another
134:11 show. Except now this is more analytic. Right? So this is
134:15 more persistently agitated. Okay, and what does that braid into it,
134:20 into a reef and into the back flat and then into the back reef
134:27 . And then boom, the bottom out. This is a marine shale
134:30 drowns out your carbonate sequence. that's a major cycle. Contact.
134:35 correlates all the way across south All right, and you see how
134:39 deflects all the way back to the line because that is a marine
134:43 This is all carbonate stuff in Okay, everybody see how this is
134:48 together. Right? Environmentally? And can see the cycle contacts. Looking
134:52 deep over shallow, deep over shallow . Right. And that's tracked nicely
134:58 the by the S. P. . But then look at the caveat
135:03 here, look at the basal part the reef here it is tighter and
135:10 upper part is porous. Right? see the increase in ferocity and look
135:14 the sp responding to that, You might miss B miss. You
135:19 be mistaken. Right? That this related to a deepening effect or something
135:23 that because everything's kicking back. That's dye genetic effect. Right? You
135:28 to be concerned about. It's a democratic part of the reef. It's
135:33 deeper part of the reef. It's um a critic less permeable. The
135:36 part has great processing firm. The sheets have great processing firm that all
135:42 clean on the S. P. this little nose right here is reflecting
135:46 deeper, less porous and permeable part the reef. Okay, Everybody see
135:51 . Okay, so this is what try to do. You try to
135:56 how the log responses tracking some of deposition all packages. All right.
136:01 another example from Saudi Arabia arab I've introduced you a little bit to
136:06 arab D. We're going to talk about that in a minute.
136:10 And you can see the this is complicated diagram. We've got sp log
136:16 the left. We've got a sonic on the right, for porosity.
136:20 gonna have to take my word for because these are all with a
136:25 which is the way you don't want do things anymore. The purple is
136:29 ties fabric. The blue is So there's a there's a digest over
136:34 here. But the question is whether dia genesis buggers up ferocity or not
136:40 , it doesn't. Okay, so you look at the rock data from
136:43 faces perspective, this is a shoaling that comes up into high energy grain
136:51 represented by yellow right there and then bottom falls out. The gray represents
136:55 deeper subtitles. So deep over So that's a cycle contact and then
137:01 shallow back up into a high energy stone over lane by Backstrom a critic
137:07 . And then red beds and evaporates top of that. Okay, so
137:11 S. P. There's a cycle the major cycle context right there?
137:17 . P. Really doesn't respond to , right? It didn't kick back
137:21 it did in the previous example. this kickback that you see up here
137:26 not due to strategic graffiti. This due to dead oil. Dead oil
137:30 some of the porosity. All So that's that's why the permeability kicks
137:35 on the S. P. So S. P. Really doesn't track
137:38 cyclist city. But look at the log nicely tracking that increase in ferocity
137:43 the top and then right there at cycle contact. A major decrease in
137:49 . And then you see a general in ferocity towards the top, but
137:53 right at the top. Right? the top is the ceiling faces the
137:57 beds and evaporates the type of laguna eight. Okay, so here are
138:03 proxy logs sort of nicely traps this . Okay. Better process preserved toward
138:08 top. The upward selling sequence. what you'd expect unless you know,
138:13 something unique about the dia genesis of deeper water carbonates. Now, here's
138:20 caveat here. The organization really didn't any role. Okay, so it's
138:26 a situation where the delay might replace grain fabric but it didn't modify the
138:31 . Okay. Didn't over grow into poor system. Didn't plug process or
138:36 like that. All right. But one example where we did have the
138:41 effect of demonization. Alright, so changed log suites here. It's
138:47 which again doesn't show any cyclist city gamma reads are Galatians, carbonaceous material
138:53 there's not much in this sequence and changed a neutron porosity log here.
138:58 cycle contact again is right here where go from grain stone into a deeper
139:04 . Look at the proxy log here you get sorry, you've got the
139:10 of the same sequence on top of . Right. Same pattern. I
139:13 showed you. But look at the log. It's all over the
139:16 Okay. And it's all over the because of the detrimental effects of the
139:22 genesis. Alright. Sometimes the lower like you see here is due to
139:27 demonization, not just replacing the grain , but growing into the poor system
139:32 an overgrowth cement. Okay. And the poor porosity is due to its
139:41 . It's due to just unfavorable die . But most of the, I
139:46 if you look at this, most the low porosity is associated with the
139:50 steps, right? The lime stones this one here have a little bit
139:55 . That's and hydrate, sorry, of the, most of the stones
140:01 the not most, most of the stones are less dramatized fabric has the
140:07 porosity like you see here, you see the caveat here, you've
140:11 got to be concerned about the over of the dia genesis. That's something
140:16 we have to deal with in the of carbonates. Okay, And then
140:21 you're on an overall cleaner carbonate right? We talked about the nature
140:26 cyclist. E on these platforms, ? These repetitive cycles that repeat over
140:31 over again. Here's the rock data breaks out the cycles of sedimentation.
140:37 a gamma log. These are all non carbonaceous non are Galatians de positional
140:45 . So there's no response on the right to break out that cyclist
140:49 It's only the major deepening effects where you incorporate some articulations and carbonaceous
140:57 and then you get a reading on on the gamut. Okay, so
141:02 stacks cycles read clean. If you're to try to break him out with
141:05 log data. This is probably where want to use the porosity.
141:09 Look for the increase in ferocity and it this way. Right, decreases
141:14 cycle contacts. Okay. This is going to lead us into our discussion
141:20 what we call composite cycles. Where these platforms we have these composite cycles
141:26 read clean on the gamma and they relatively thick at the base. They
141:32 thinner and thinner at the top. then you switch around with a relative
141:37 in sea level. You switch around a thicker cycle and with a gamma
141:42 at the base. So that's the of the composite cycle. The base
141:46 the composite cycle also marked by gamma would be off the bottom of this
141:51 . Okay, so I'll come back that in a minute. I just
141:57 you to appreciate where I'm going ahead this discussion and then the second gross
142:01 environment, Our basic carbonate settings or . And deep water where you get
142:08 . Right? And I've already talked the model for making evaporates in deeper
142:14 . And so with respect to basic , you're probably wondering why anybody cares
142:20 breaking out these packages in deeper Well, for Western Canada, the
142:26 actually is where some of the shale carbonate deposits in these basin fills come
142:32 . Right. This has implications for you interpret the seismic data. What
142:37 straddle geometries mean? And so to a handle on that Stokes use the
142:43 log to break out these clean of stones and otherwise Shelly sequence and define
142:51 client of forming aspect for the carbonates shales. And he could prove where
142:56 shells were coming from. Okay. then with respect of APA rights,
143:01 we take a bucket of water, I said earlier, right. The
143:04 thing we drop out is carbonate. ? And then what comes out after
143:12 ? And hydrate? Right. And , hey light, but usually the
143:16 light gets re dissolved during each So what do you do? What
143:21 you call that when you go from to and hydrate, you call that
143:25 cycle of grinding upward cycle. A brining upward cycle. And it
143:31 out a lot of these basins evaporates made up of a series of grinding
143:35 cycles. Okay. And they have log expression and the log expression is
143:40 to what the density log because what the density of and hydrate? It's
143:47 little bit over three, which is than any of the carbonate material we've
143:51 talking about. Right cal, size . Dolomite is 2.85 and hydrate
144:00 I think three point oh three, like that. Okay, On the
144:04 lock. So let me show you examples of how they tried to use
144:09 . Okay, so the first example is Western Canada and the western Canadian
144:15 basin. The controversy is that we , we've come out of the cooking
144:24 , come out of the cooking lake which is a broad shallow water carbonate
144:29 on which you have marginal reefs Or you have these atoll reef complexes
144:34 like red water that I introduced you briefly. And then that's drowned out
144:39 the the Duvernay formation. Okay. the Duvernay or di Verney, depending
144:45 who you ask in Calgary, they'll it differently. Is the source rock
144:52 Western Canada? This is the one has up to 18% T.
144:56 C. Okay, and so you out the cooking lake. Okay.
145:02 then this is succeeded by the art formation. The art in formation is
145:06 marine shale, a greenish gray That uh the controversy about the origin
145:13 nobody, no, nobody knew where stuff was coming from. Before Stokes
145:17 his dissertation. Alright. And the Stokes figured where the origin is coming
145:23 are coming from Haley geographically. Was looked at or used the reason activity
145:30 to break out these cleaner limestone Okay. You see these things right
145:35 , he was able to map these like the cameras member. These are
145:39 baseball carbonates and otherwise Shelley based on sequence. Able to establish a client
145:48 me aspect and show where the where origin shell was coming from.
145:54 so that's an application of the receptivity . And let me set this whole
146:00 up here. So western Canadian sedimentary in Alberta is a big U shaped
146:07 like this with carbonate, shallow water deposition on both sides. Okay.
146:13 then base and fill. But most the basin fill is uh,
146:22 deep water carbonate. Okay. Except the periphery. Okay, around the
146:28 is where you get the origin Okay, right here and people shot
146:34 off this western margin. Right? saw this kind of relationship. There's
146:40 carbonate platform dropping off into deep There's the on lapping basically restricted wedge
146:46 art and shale. So how do interpret that byproduct of low stand
146:53 Right. They would say the shale brought in by dropping sea level.
146:59 shut down your carbonate machine here. where would you bring it in?
147:03 bring it in from the west and bring it in during low stand.
147:06 plastered up along the edge here. . That's how almost everybody would interpret
147:13 strata, graphic that geometry on Okay, But there are two
147:20 And the first problem is when people to the west to look for a
147:24 , they couldn't find it. There no known known source to the west
147:28 art and shale. And secondly, you want to drop sea level,
147:33 should you see right here? You c a Di genetic expression,
147:39 Physical and Petra graphic expression of a in sea level. Right? The
147:44 , the soil crust, things like that we talked about before and then
147:49 dissolution. Early see imitation of any genetic material. Okay. Never been
147:55 . Okay, so what's going on ? Well, what's going on
147:59 Is that what Stokes using the Activity log was able to show that
148:04 source area is actually to the north the arctic. Okay. And these
148:10 are coming in from the north. climate forms show that these shales are
148:15 like this around the periphery of the . What does this, what are
148:21 Geostrategic currents that are confined in the of the basin. What sets up
148:27 currents? You wanna guess? Trade trade ones. Okay. And trade
148:37 blow again from the Northeast. That's sets up the circulation effect. And
148:42 you just plaster the shale up against edge to give you this apparent on
148:48 . This is not real on lap the center of the basin remains.
148:53 water carbonate. Okay, so this what the iron shell looks like in
148:58 . This is what the cleaner based lime stones look like. You can
149:02 the big mac ipod two valves That means that lived there and died
149:07 . Okay, you can see little specks here. Those are Quran noise
149:11 lived out in deeper water. These wacky stones and pack stones.
149:17 Mhm. So you see the implications . Okay, so I'm gonna digress
149:25 just a little bit just to get to appreciate, you know what these
149:28 called basically restricted wedges mean? Or mean. Okay, So yesterday I
149:34 you shedding off of the carbonate platforms high stands. Right. That would
149:39 this example right here. That's not low stand wedge. That's high stand
149:44 . And then I showed you this right now from the carton. So
149:50 is stuff that's being moved along the of the platform has nothing to do
149:55 the drop in sea level. And then think about the pinnacle
149:59 We're going to talk about next These carbonate systems pro grade into the
150:04 part of the basin. They actually lap and then bury these pinnacle
150:09 But on seismic, this looks like parent on lap. And people have
150:13 this on lap to be low stand . It has nothing to do with
150:18 low stand situation. All right. then the last example in the cretaceous
150:23 tertiary is we have lots of carbonate , shallow water, high energy deposition
150:29 that are fronted by deep water basins in with pelagic chalk deposits.
150:34 And they just they just fill up whole right and they give you what
150:38 like on lap. All right, that's not true online, in the
150:42 that stuff was moved off the platform deeper water, people have mistaken these
150:47 water chalks to be low stand wedges shallow water carbonate material until they drill
150:53 and found out they were deep water . Okay, you have to be
150:56 careful here about the geometries. And then I'm coming back to the
151:02 and field of ap writes, I grinding upwards cycles are the norm.
151:06 so if you look at the density here, you look at the
151:11 right? The first phases of precipitation dolomite. Okay, yep, the
151:20 and pink and then the red and , that's what we call a brining
151:24 cycle. And look how that the tracks that right from cycle to
151:30 And so this is how the Canadians build a strategic graffiti for the basin
151:35 evaporates. They were interested to know those evaporate. If there's a relationship
151:41 the base and field evaporates and some the strategy relationships they see up on
151:46 on the platform. Okay, so the dancing log is the tool you
151:50 want to use for that. alright. And then the last environment
151:57 unique environment where along the platform, , reef or high energy carbonates and
152:05 deep water carbonate settings. Sometimes you this inner tongue right from pro gradation
152:10 stepping. Pro gradation back stepping. are the two logs that are nicely
152:16 to track that it's going to be gamma if you're deep water carbonates are
152:20 delicious or carbonaceous and it's going to the proxy logs. If you're your
152:26 carbonate that's being shed in the deep is porous. Okay, so here
152:33 a diagram and more showing more detail red water. Remember red water in
152:38 previous lecture, that was the one back stepped itself out of existence,
152:43 ? Each successive cycle ran out of . So here's part of the eastern
152:48 margin of red water. So the reservoir units are the re flat and
152:54 reef margin. Okay. And then can see some of the portal grain
152:59 shed in front especially as they pro out. We talked about this,
153:04 ? How could build out and you , companies like s So we're not
153:10 to spend money to core some of wells here. They're hoping to resolve
153:14 inter fingering relationship just from the Okay. And so you know,
153:19 cored enough of this to know that is the relationship that you see from
153:23 facing standpoint but they wanted to also what the log response was for
153:27 So let's just let's just talk talk the cycle here. The red and
153:32 pro grades out to this position It's shedding material out into the
153:36 What happens right here? This is back step, right, a main
153:41 step, this is a major cycle . We shift our brief deposition back
153:46 build up and out. Alright, when we shift it back, what
153:50 you do along the margin here. have incursion of these deeper water based
153:56 carbonates. Right. You have this fingering effect, right? And they
154:01 to be able to map this on margin but they don't want to spend
154:03 to core. And you can do here by using both the porosity and
154:08 gamma ray kick. Alright, the ray responds to the green deep water
154:14 . The proxy log responds to the for slope stands. Okay, so
154:20 an application of some of the log off the edge of some of these
154:24 , where you get this programming back programming back step. Right. Alright
154:31 let me finish up with one last here, which is called composite
154:36 Composite cycles again are developed up on overall shallow marine carbonate systems. All
154:45 . That what we see is when have a major deepening effect.
154:48 We create accommodation. And then the is how do you fill that hole
154:54 with time with successive cycles. And what you do is you fill it
154:59 with a number of stacks cycles lower are thicker with subtitle dominated faces.
155:06 cycles are thinner and thinner and thinner more title, flatter perry title.
155:12 then when you flip it back around a thicker subtitle dominated cycle that's the
155:17 of a new composite cycle. this is again, this a little
155:23 hard to explain here. Uh, always struggled with this with my cartoons
155:28 to show this, but let me if I can do this. All
155:33 . So, let's start with a here where we come out of a
155:37 flat at the base. Right? know that shallow water that's right up
155:41 where sea level was and then the falls out right here. So deep
155:45 shallow. That's a major cycle And a lot of times our initial
155:51 , we start out with a lot accommodation. Right? We created that
155:55 . And our first cycle from here here is relatively thick and dominated by
156:04 subtitled carbonate. Right? We still up. All right. But that
156:09 deepening incorporates some articulations. Carbonaceous So we get a nice gamma kick
156:15 there. That's the base of what going to call the composite cycle.
156:19 , the first cycle in that composite is from here to here. And
156:25 see the next cycle is thinner. got a little bit more title flat
156:32 . You see what we're doing Each cycle is getting thinner, we're
156:36 out of space for a lot of faces. It's mostly perry title or
156:42 flat. And then when we turn right here, this is a major
156:48 event again by definition, that's a cycle. Contact. We start the
156:54 composite cycle, we create that accommodation and now we do the same thing
156:59 and over again. Okay, that sense. So what I'm trying to
157:05 is that the gamma here is not to pick up these smaller scale cycle
157:10 . Right? They read clean. going to pick up the boundaries of
157:13 composite cycle and it's a composite cycle that you can correlate over a huge
157:20 and then you fill it in with rock data or other log suites like
157:25 to build the smaller scale cycles. , so let me let me show
157:31 what I'm talking about here. So is from a Devonian sequence in western
157:36 called the cake river. And this part of a case study. I'll
157:41 through quite a bit of detail next , but we're dealing with a shallow
157:46 carbonate platform in the devonian and it's up of these composite cycles.
157:52 And the composite cycle goes from the of this tidal flat to this position
157:59 here. Okay. And so we out of the title flat represented by
158:05 and we deepen. And so what's first cycle? Our first cycle is
158:09 right here to the top of the and you see it's relatively thick and
158:14 dominated by green subtitle carbonate. And then look at the subsequent
158:19 The overall get thinner and thinner with white. Right or subtitle or more
158:24 title or title flat faces and then turnaround point would be right here.
158:30 , so a number of these These are basically the 123 m thick
158:35 cycles that stack into a composite cycle ends up being 7 to 12 m
158:42 , bounded by gamma ray expression right gamma ray expression right here. These
158:48 the cycle contacts that we correlated all way across this carbonate platform over a
158:54 of 35 miles. Okay, these scale cycles you can pick up on
159:00 proxy logs, they don't have the lateral extent. They they only correlate
159:06 hundreds of meters or a few Okay, so the big major cycle
159:11 always correlate for larger distances. The scale cycles like these correlate for hundreds
159:17 meters or a few kilometers. everybody understand what I'm saying. So
159:23 actually could we actually could have used rock data by this. We had
159:27 core control. We could have used rock data by itself to make this
159:31 graphic correlation. Alright, but we the gamma ray in concert with the
159:38 city to build that regional correlation. one last example from the Mississippi and
159:44 Williston basin. This is a gamma on the left and the DNC log
159:48 the right. I've highlighted the and and red. Okay. And this
159:54 all ground truth with either core data well cuttings that were thin sections.
160:01 . And so what do you see ? A series of stacked repetitive
160:05 That's what the arrows represent little upward sequences. Look at The basal cycles
160:11 thicker, right? With a greater of non red or subtitle carbonate.
160:18 then the overlying cycles are thinner with greater proportion of of an and
160:25 which is related to restricted lagoon or flat. And then what happens right
160:31 ? That's the turnaround point where you dramatically. Okay, so the composite
160:37 contact is right here for the upper . The lower cycle composite cycle contact
160:46 probably right here. Alright. And two contacts correlate all the way across
160:51 Williston basin. Alright. These smaller cycles correlate for shorter distances. For
160:56 reasons I just said right, everybody appreciate what I'm saying. That's
161:02 composite cycle concept. Okay, this how we try to build a regional
161:08 graphic framework. Okay, Alright, let's finish up with a couple of
161:15 about the other uses of the log . Right. These are historically the
161:20 that people in industry have tried to logs for sonic log for proxy for
161:27 porosity for fractures, neutron density for dolomite, limestone, p curve and
161:34 modern tool here breaks out dolomite versus versus some of the classics.
161:40 spectral gamma ray, gamma ray. have to be careful gamma ray.
161:45 you know, everybody thinks gamma ray responds to our delicious or carbonaceous
161:51 That's not true Dulles stone. If incorporate uranium and Angela stone, which
161:56 can easily do you get a response the gamma. Okay. And if
162:01 don't run what's called a spectral gamma rate log where you separate out the
162:07 signature from the potassium thorium signature, you could be misled strata graphically.
162:15 . Image logs used to detect They're used to map sedimentary structures
162:22 NMR log is a nuclear magnetic resonance . This is used in plastics maybe
162:29 often now to pick up micro but it has great application that carbonates
162:34 hasn't been used with the same And CT imaging is all driven by
162:40 price of oil is an expensive So when the price of oil is
162:45 over $100 a barrel, companies will CT imaging for porosity for sedimentary
162:52 fractures and things like that. so let me just show you some
162:56 the applications, but also talk about of the pitfalls here. Alright,
163:00 the first example here is the use the p curved breakout mythology and this
163:06 data from west texas in the Permian this is an example where companies ran
163:13 log in the non pay zones of reservoirs that they're not going to spend
163:19 on coring. And so, but still want to know the strategic graffiti
163:22 the non pay zones. And so ran the P curve to differentiate not
163:27 limestone from Dolomite purple from light right? The light blue would be
163:33 , but they also ran it for classics. They picked up these,
163:38 silt stones. See the yellow zones on the log. Those are the
163:43 stones. They were able to pick with P curve and they used that
163:46 correlation, right? Because they thought silt stones were wind, wind blown
163:51 blown across the non pay part of reservoir during drops in sea level.
163:56 . And that's how they set up regional strategic graffiti in the non pay
164:02 . Then image logs. Mhm. everything everywhere from trying to break out
164:11 topography. Right. But we talked the caveat for cars strike, not
164:15 cars is near service and fresh You can get burial cars. So
164:20 need to be aware of that. people pick up the cycle contacts with
164:28 image logs, here's a change from shallow water carbonate with an inferred exposure
164:35 and a return to deep water, regular lime stones. So that would
164:39 a cycle contact as well as a surface. Okay, And sometimes image
164:46 will pick that up. Here's another cycle contact where you go from lighter
164:50 shallow water lime stones abruptly into a water, not regular wacky stone or
164:56 stone. You see how that picked on the on the image log.
165:03 here's another example where you paired photographs show the skull wacky stone of build
165:12 faces in core versus the image Nagy alor stylistic fabric. Okay,
165:22 that's pretty good. And then here's things start to fall apart.
165:28 So here's a in fact shame on bureau for publishing this because this is
165:35 Bureau of Economic Geology in Austin, ? This is the state arm that
165:42 the all the oil and gas activity the university lands, Right? This
165:46 where the state makes a ton of from royalty. Right? So they
165:50 a staff that's supposed to supervise the by companies on their land and sometimes
165:57 do independent studies and publish. And , that's what they did here.
166:02 look at the image log over Right? It sort of looks like
166:05 laminated fabric. Right? And they this to be a tidal flat.
166:10 then look at the core on the the course, not even from the
166:13 . Well, okay. That's why said shame on them right there.
166:18 like contrasting apples and oranges. I mean, if you're gonna show
166:23 rock data, it should be from same log that you're showing the
166:26 Right? But look at this. looks laminated. This is not
166:33 This is stylistic. Okay. And at this prostate here. That's financial
166:38 . Yes, I would agree. title flat, but you don't really
166:42 it so well expressed over here. . And so I can tell
166:46 I've had personal experience with this kind stuff before. I've had clients call
166:51 up and tell me to go look core data. Had one client working
166:55 the western the four corners area in western U. S. And he
167:01 this well run an image log on . And he called me up and
167:05 said, I want you to go at this core. I want you
167:07 describe this core. It's all tidal . I said, well why do
167:12 want me describe the core if you know his title? But how do
167:14 know his title? Fact? I got an image log and it
167:18 just like the one here on the on the left. Okay. Just
167:22 ft of laminated carbonate. That's a flag right off the bat. Right
167:27 get 100 ft of laminated carbonate on tidal flat. Right, what did
167:32 see on tidal flats? Small scale to repeat over and over again.
167:37 the laminate stuff only occurs on the . Right. Which is a small
167:41 of that title. Flat succession. in my mind that was a red
167:46 right off the bat. Right. I said, okay, give me
167:49 logs and I'll go look at I went and looked at the core
167:52 it was 100 ft of deep water on carbonate. Okay, borrowed.
168:00 it looked just like this. so sometimes the image logs bust.
168:06 , so just aware that there's a bit of a risk here. When
168:09 try to interpret these image logs. , here's another example where they related
168:16 darker holes here. I think most would say that's what ferocity. The
168:24 holes are imaging ferocity, but here thought they were imaging these tubular tempest
168:30 that I've talked about right where the gets filled in with slightly coarser grained
168:35 . And so I think this is bust as well. And I think
168:38 is this is probably ferocity here. , again, look at the course
168:44 , there are two different cores 67 25 64. Uh, these guys
168:53 me up a wall here when they this kind of sloppy work because this
168:56 not, this should have never been right. If I was an
169:00 I would never let this stuff get . Right? You can't compare one
169:05 well to another chord another. Well has an image log, right?
169:11 not cord and say that's the same of fabric. Okay. And then
169:18 is a tool right? Where you pick out the amount of macro versus
169:24 porosity and it's all based on the you get on the, on the
169:30 tool here. When everything is skewed the right, just to the
169:36 That would be macro porosity and low saturation and probably higher permeability when everything
169:43 skewed just to the left. That means a predominance of micro porosity,
169:48 usually translates to lower permeability. And when you get both bumps together like
169:53 did on this log, this is mixture of macro and micro porosity where
169:58 have may have micro porosity for storage hydrocarbon, usually gas, right?
170:04 example. And then the macro porosity the permeability to help get it out
170:08 that rock. Okay. I find a lot of companies don't use this
170:14 very much in carbonates, use it in classics to pick up on micro
170:19 clay coats and sand stones and stuff that. But I think there's great
170:24 here to the carbonate world. And , I got involved in a detailed
170:28 years ago for Anadarko when they were the south texas cretaceous carbonates and they
170:37 NMR in order to in order to NMR as a proxy expiration tool.
170:48 ? They wanted to they wanted they to use this tool to sort of
170:53 the cretaceous trend regionally to map out amount of macro versus micro porosity because
170:59 cretaceous in south texas and notorious for a lot of secondary micro porosity.
171:06 so what I did with one of geologist hank Dewitt was we spent a
171:12 in austin going through all the Cores for the cretaceous Edwards trend and
171:19 we broke out the faces from the data. All right. You can
171:25 for reef, you could tell the the back reef flat, the
171:29 uh generally the faces that you And then we had we got the
171:37 to take plugs for us, For all the faces. And so
171:41 did a double blind study. All . And so what they did was
171:45 ran NMR. They did P and analysis reach plug to get crossing perm
171:50 then they ran NMR to calculate the of macro versus micro porosity. And
171:56 they gave me the samples and I a thin section off the edge of
172:00 plug. Okay, impregnated with the epoxy like you see here. And
172:05 I use the white paper technique to up the micro porosity. Okay.
172:10 I visually estimated the amount of macro micro porosity. So, that's these
172:15 right here. And then here's the processing perm for that sample.
172:20 If you go back and we compared data, we came up with the
172:24 coefficient of 0.71, which is pretty . Okay, That's a good,
172:29 pretty strong correlation that shows you that NMR tool nicely picks up the amount
172:35 macro versus micro porosity. So, is some of the reef debris on
172:40 reef flat, where you've got a of macro porosity and some micro
172:44 And then here's the lagoon where you have great permeability because it's mostly micro
172:51 . It's mostly within the grains or the MMA critic matrix and some of
172:56 micro porosity you would never see without white paper technique. Okay. But
173:01 , this tool has a lot of and I think it's been under utilized
173:07 a lot of companies and we'll see they, if they pick up on
173:10 or not. Okay, so that's chief use of the N.
173:13 R. Tool is for to break the micro porosity versus macro porosity.
173:21 . Any questions about the log and seismic part of the story, not
173:27 seismic but the law. Let's take five minute break here and we'll finish
173:33 for the day with a brief discussion the application of seismic data and that'll
173:38 it up for the day. Okay. So we're gonna finish up
173:45 a short discussion about application of seismic to carbonates and part of this is
173:50 want you to appreciate some of the of interpreting seismic data and carbonates.
173:55 , I'm not, I'm not a . Usually when I get involved in
174:01 that come in after companies have drilled seismic right in the US. Everybody
174:07 off the seismic First, the Canadians just the opposite. They drill off
174:11 rock data. They hardly ever incorporate data into their play evaluation unless the
174:18 company moves to Canada and forces them do that. And so you can
174:23 the historical applications here for seismic and . It's first of all to understand
174:28 regional or local fizzy graphic setting, ? Platform versus ramp that we've talked
174:34 ? You want to have some sense that from your seismic data. But
174:38 say historically most seismic data has been to do what to find the
174:42 right. The buildups and recognizing right? The different styles of reefs
174:48 talked about and we haven't talked about the different styles of reef yet,
174:53 reefs and mounds, Right? And you want to find ones that are
174:56 just build up the ones that have , right? That's the goal,
175:00 ? Something that you can yield So we'll start with some examples
175:07 And this is data that I just out of a PG memoir 27 on
175:11 strategic graffiti. This is a tertiary data from Southeast asia. You see
175:16 bump, you see the on lap the material and then deeper water carbonate
175:22 on top of that bump again. caveat here is that, you
175:26 when you interpret this, somebody's the Tennessee's interpret these bumps as
175:32 writer reefs. But what's the first that you should ask before you jump
175:36 that conclusion? The 1st 1st thing ask is, you know, what's
175:41 regional setting, Right? Which way the open ocean? Because where is
175:45 good reef development? It's only the platforms that face the good open ocean
175:51 . Right? And if they face and also face into the wind.
175:55 even better. So which way is ? Which way is leeward?
175:59 Those, those are fundamental questions you to try to address because just because
176:04 get a bump like this on side doesn't necessarily mean reef. All
176:09 You're going to see examples where later can take a series of stack cycles
176:13 you can build topography like that. , Sometimes this topography could be created
176:19 structure by movement of faults. And sometimes this could have nothing to
176:26 with three if it could be related grain stones, a series of stack
176:30 stones that build topography. Okay, you can't just jump to this conclusion
176:36 a bump on seismic is a Okay, now this turned out to
176:40 reef. Okay. But I want to appreciate some of the thought
176:45 thought process that needs to go As you evaluate whether something like this
176:50 likely to be a good platform margin or or not. Second historical uses
176:57 try to understand the regional evolution of carbonate platform systems. You know,
177:02 the modern, I showed you how shed sediment. Right. And they
177:06 in a bigger scale features. I you that for beliefs. I showed
177:10 on keiko's how those reefs organized in longer linear features. We'll carbonate platforms
177:17 the same sort of thing they shed . So here's the seismic data from
177:22 Bahamas that was taken back in the and today, as I showed you
177:30 . Right, this is all shallow carbonate platform. This is all less
177:35 23 m of water depth until you to the edge here. Alright.
177:40 look back here in the late it was actually a series of smaller
177:44 platforms. There's Andros Island today. , so that's called Andrews Bank.
177:50 then there was a deep water and in between another shallow water bank,
177:54 embodiment another shallow water platform. And happened through time they've shed sediment.
178:00 . They filled in the hole they've . Okay, so this map came
178:06 this diagram that I showed you Right, where you had these deep
178:11 and famous they were asymmetrically in filled sediments loft off the top of these
178:17 . Right. This is the in upper cretaceous. If you look at
178:23 paleo geography for the Bahamas, it still in a subtropical setting basically where
178:28 is today, which is where it's today by general easterly trade winds.
178:34 knowing that and knowing what happens today the modern right, we know that
178:39 going to preferentially shed material off the sides of these platforms and what are
178:45 going to shed principally in a general trade wind built coarse grain stuff,
178:52 grain stuff, but the weaker Yeah, fine grain. Right.
179:00 you would predict that to be fine based on what we see operative
179:04 So the University of Miami cord this that's exactly what they found,
179:09 Mostly silt and mud size carbonate The only coarse grain stuff that comes
179:14 is during a hurricane. Okay. then appreciate the asymmetry. Okay,
179:19 keep in mind these carbonate systems are . They're going to shed material but
179:24 not going to shed material equally from sides. They never shed equally from
179:29 sides. Okay. And then with to a ramp setting, this is
179:35 this is part of a ramp succession the Permian in west texas. And
179:40 want you to appreciate that ramps, know, they do this right?
179:44 go out slowly into deeper and deeper . And then when they come out
179:48 deeper water with increased substance, what they start to do here? They
179:53 over, right? You see this effect on seismic, that's this effect
179:59 here. Okay. Everybody see this right here. That is a that
180:09 uh, this taken by some people be like a little mini platform margin
180:15 a ramp margin or something like There are no margins in the
180:19 Okay. There's a ramp crest right the shallow part of the ramp
180:24 close to shore line. But this way out into the basin.
180:29 so the companies have mistaking this to a focus of shallow, high energy
180:34 . No, you're out in the of Bracke pot. You're out in
180:37 world of criminal. It's okay, is deep deep water. Okay,
180:42 you're going to see that this has for localizing some of the play types
180:47 going to talk about next weekend. is where the down the ramp build
180:52 occur in the upper paleozoic or in lower paleozoic where you get pinnacle reefs
180:58 stuff like that. They're taking advantage that cell, a topographic change in
181:02 water. That's where they initiate and they take off. Okay, appreciate
181:08 is not shallow water. The high step is off to the left of
181:12 diagram. Okay, dear. Professor asked something regarding last light. The
181:22 that the sharp age is not the of the, you know, it's
181:27 the edge of the ramp. So basis you're saying that? I could
181:31 understand? Please repeat that. That's rollover effect in deeper water due to
181:37 increase in subsidence as you go into basin. The substance starts to
181:42 You see the ramp profile steepens a bit but that steeping has nothing to
181:47 with shallow water. Okay, people that to be a shallow water effect
181:56 ? Like mini platform margin or something that and that's not the case.
182:01 is all deep water. Okay, you very much. Okay, and
182:14 historically we've used seismic data to break carbonate buildups. This is data that
182:20 just lifted from a PG memoir Right? This is a classical seismic
182:26 that people want to look for on two D. Seismic data to detect
182:31 build up. Right? So you see the thickening of the build up
182:35 , thinning of overlying cycles, grape , right on lap of the overlying
182:41 , disruption of the seismic event mounted reflection, free internal character. And
182:47 where does that come into play? comes into play? If your build
182:51 is more porous than the underlying whether they're carbonates or classics, you
182:56 get a sag effect. Right? when people see sag, they get
183:01 happy because they think that's the the effect. And then if they
183:05 pulled up they get very sad because usually means the buildups tighter. Okay
183:11 the underlying sediment, whether it's carbonates classics. Okay, so let me
183:18 with you some data that Exxon published back in the early nineties. And
183:24 I told I told you I worked Exxon. So I'm familiar with some
183:28 this data. This is a postmortem of 60 case studies that they drilled
183:35 of two D. Seismic data and the interpretations were using the criteria that
183:42 just showed you everything was interpreted to a poorest build up. Okay.
183:49 then they did the postmortem evaluation after drilled them and some were great reservoirs
183:54 some were dead. Okay. And here's the breakdown of the 60 prospects
184:01 they drilled off a two D. . Over half of them turned out
184:05 even to be a build up. . And then they did the postmortem
184:10 and I've been involved, I was in some of this. Okay.
184:14 you can see the breakdown here. sometimes they drilled an irrational remnant.
184:21 they drilled a pile of shale. solicit plastic mount is a shale mountain
184:26 I've seen the state in southeast You know, the tertiary is a
184:30 where you get lots of good tertiary and some of these reefs are over
184:34 ft thick. I mean, they be potentially great reservoirs. And I've
184:39 the seismic where you see a mounted you see on lap you see
184:43 you see sag underneath. Oh, a tertiary. That's amazing reef.
184:47 drilled it pile of shale. that's the risk. Alright. How
184:55 you eliminate some of that risk? want to think about, where would
185:01 get the better reefs? Right. where wouldn't you get good reefs?
185:05 wouldn't get good reefs and a basin filled with a lot of shale or
185:09 fed by rivers and things like Right. And so that's how you
185:13 eliminate some of the risk by thinking what controls the distribution of these
185:18 They're not going to be in environments there's a lot of cloudy water.
185:22 ? No light penetration, They're getting by clay. Right? The filter
185:27 get choked by clay. That's not . Okay. And then continuing sometimes
185:34 drill salt volcanoes get drilled all the as buildups. Right? That's
185:39 very common in the rock record. they couldn't blame it on the
185:43 they started to blame it on the . Multiple effects on migrated diffraction
185:49 Here's the cop out bad data I guess when you couldn't blame it
185:57 anything else, you blame it on data. All right. I think
186:00 bigger problem here is over interpretation of . Alright, Back in the early
186:06 , which is a boom time. ? When companies the price of oil
186:11 increase and companies were, were desperate people, right? They were going
186:16 and hiring metamorphic tetralogy gist and triggering anybody to interpret seismic. Right?
186:26 so they would show them what to on seismic, right? How to
186:29 out everything. But what did they ? They didn't understand carbonate systems,
186:35 ? They didn't train them in carbonate . So they didn't understand what controls
186:39 occurrence and distribution of reefs. So what I mean by over interpretation of
186:43 , right? People are just taught to do it off the seismic to
186:47 for the bumps, but they don't what controls the occurrence and distribution of
186:51 reefs. Okay. And then the two examples here. So that's the
186:56 of the 53% and then the 47 so percent over here. It turned
187:03 that uh, 28% was a dry up. Right. That's the risk
187:08 the trap mint or charging 5% was had oil but not enough volume to
187:16 money for Exxon for that basin. then 13% turned out to be a
187:20 discovery for Exxon. So here's here's the breakdown of that,
187:26 Sometimes it was a source rock right? Either not mature or no
187:31 to a nearby source rock. Here's dye genesis part of the story for
187:36 , Right? That's always a Sometimes a leaky top seal,
187:41 Maybe preached by faulting or something like . Sometimes they drill below the oil
187:45 contact again. Sometimes they found the , but not enough to make
187:51 And then the commercial discovery. So I, having worked for
187:57 I applaud them for doing this because a very conservative company. They don't
188:01 to admit that they make mistakes, they're not successful at everything they
188:05 Okay. So, I give them for publishing this because I think it
188:10 put into perspective the risk that's associated prospecting off of seismic data.
188:17 This is where you want to bring other geological understandings, right? If
188:20 upsetting and make sure you understand exactly that setting would be good for reef
188:25 or not. And some of it to do with the age of the
188:29 to write because some geological time periods not good periods for good reef
188:34 All right. So having said that I show you the seismic line here
188:39 Libya, you know, and ask to invest your money. You
188:42 you might be a little dubious about to kick in some money here.
188:47 you see the seismic bump, you the on lap you see the
188:51 you see a great sag effect right . Alright. That's obviously the build
188:55 . And if you drill that, would have drilled a giant oil field
189:00 idris which was later renamed. Uh can't even remember what it's been
189:08 but this is pale Eocene age, ? Lower tertiary and Libya. This
189:16 one of these deep water pinnacle reefs down the ramp that we talked
189:21 Right. And that rollover position, where you get this. This build
189:25 developed. It's a one well but it's wonderfully thick. Right?
189:30 a 1500 ft thick. Almost 1000 of pay. It produced 40,000 barrels
189:35 oil a day. 1.5 billion barrels oil in place. Okay there.
189:43 you can find them, right, gonna make a lot of money.
189:48 then here's one last example here for for a pinnacle reef and the keg
189:52 in the Devonian, not quite as build up, maybe 600 ft or
189:59 thick. But you know, where's build up. Alright. It's harder
190:03 see here even though this is better D. Data that I just showed
190:07 for Libya. The build up is here in the keg river. And
190:11 three D. Data you would see beautifully. But two D. Data
190:15 the the this has given me by of my seismic colleagues in Calgary
190:22 This is his list of criteria that looked for. And he actually found
190:27 the best way to pick these reefs was to see the differential compaction in
190:32 overlying slave point. Right? It's around that reef topography and that's that's
190:38 the reef is. It's right And uh that's how they would identify
190:43 off that seismic. And then one comment here about the seismic data that
190:49 that has to do with the fact sometimes apparent build up topography on seismic
190:54 be created by stacked Scholl complexes that nothing to do with reefs.
191:01 And so this is a field called patent. It's one of the larger
191:06 and gas fields. I think it's gas and condensate field in the in
191:12 smack over in southern Arkansas. And it's a not had on
191:20 You see the you see the sort impression of build up topography here but
191:26 has nothing to do with reefs. are rituals cycles and stack.
191:31 And they're also influenced by structuring. here's the interpretation, the whole complex
191:36 our new created on top of these blocks. Okay. And that topography
191:43 that apparent build up looking expression. these are like sand body systems.
191:50 , So just keep that in mind not all apparent build up topography is
191:54 to a briefing in the rock Okay. And I'm gonna actually show
191:58 some other expressions next weekend that have to do with reefs. Okay.
192:05 . So everybody appreciate that really. is just to get you to think
192:08 the caveats and the risk. And , the goal here is to try
192:13 eliminate as much risk as you Right? You try to do that
192:16 the technology, but you also do by understanding these carbonate systems.
192:21 Understanding what controls the occurrence and distribution some of these depositions packages. All
192:29 . The last thing I wanted, comment I want to make here is
192:32 modeling ferocity office seismic data. There's a big push towards that.
192:38 could do that with two D. data. That's called acoustic inversion.
192:42 now people are doing it with the advanced three D seismic right there trying
192:46 map the blobs across the blobs off the three D seismic data.
192:52 I want to show you one of pitfalls of doing that. Okay,
192:57 , because I think I've already mentioned right ferocity does not equate to permeability
193:05 . Right. So you can have ferocity and never squeeze anything out of
193:10 poorest turnip. Okay, conversely, could have lower porosity carbonates that have
193:16 permeability that can yield hydrocarbon, But companies might walk away from that
193:22 , oh it's too low porosity and it's not. Okay, so on
193:29 , on blackboard, you have this spe paper that was published by Edith
193:36 , she carbonate geologist by training but became, she worked for Amoco for
193:42 while and then she became an she lives in Tulsa Oklahoma. She's
193:47 spun off of oil and gas. think she's into, I don't know
193:53 it's carbon capture or if it's into some other aspects of um you
194:00 I don't know, but she's not oil and gas stuff anymore, but
194:05 you know, I taught internally for for a couple of years and she
194:09 me this paper to use in my . So I want to share with
194:12 this little case study because it nicely some of the risk or pitfalls of
194:17 to model proxy emphasizing. So here's peninsula cutter that we talked about,
194:24 and we talked about the the Saka occurs up here in this, in
194:30 position right here and I mentioned this oil field here called do han oilfield
194:36 . Which basically lines up with all big oil fields in Saudi Arabia.
194:40 ? As part of that structural trend runs like this and back in the
194:46 back in the eighties story. Uh Qatari government opened up this offshore block
194:52 Jurassic expiration. This is before they the big giant Northfield Permian gas
194:58 Okay. And so they opened it for exploration. And Amico was interested
195:05 chasing perhaps smaller scale versions of Duan offshore. All right, you can
195:11 the numbers for Duan. It is giant oil field. Okay. And
195:16 showed you this picture before. It's hard to miss this out in the
195:20 . Okay. But, but I to turn this into sort of a
195:24 case study. I want to show the arab d how the arab he's
195:27 together in this part of the world both Qatar. And also would apply
195:32 Saudi. And then I want to you the risk of trying to model
195:38 or some of the pitfalls of modeling . The office seismic. Alright,
195:42 the F. D. Is up . Upper Jurassic age. Alright.
195:48 overlaying by the, the guitar strata unit. So, these other arab
195:56 . B and C. These are shallow water and evaporate IQ sequences,
196:01 ? You can see some of the that come into play here evaporate that
196:04 right on top of the air B probably a basin all evaporate that provides
196:09 effective top seal for the F. . Oil and gas and then everything
196:13 regionally sealed by this hip and This really thick and hydrate again is
196:19 a major deep water basin all evaporate . Okay, remember this is important
196:26 of the structural effect. Right? got the big dome a structure.
196:29 still need to seal this stuff effectively the sides and on the top.
196:34 that's probably accomplished by the hip and . Alright. But looking at the
196:39 D from a reservoir standpoint that everybody that the Air B is made up
196:44 these basically 100 ft thick cycles about m thick, that repeat over and
196:50 again. And their classical upward showing that go from muddier wacky stone.
196:56 lime mud stones at the base up grain stones. The grain stones are
197:01 skeletal and colloidal grain stones, sometimes some material mixed in. Okay.
197:09 that would be the prime reservoir Right. You've got good primary porosity
197:14 good permeability to begin with. All . And then what you need to
197:20 though, is that anywhere in these upward chilling sequences, you can have
197:24 to 50 ft of more mass more massive dolomite that comes in and
197:29 some of the anti some of the D. Okay, and sometimes that's
197:34 good thing like we talked about right, for preserving ferocity and some
197:39 creating ferocity and sometimes that's a bad when it replaces the grain stone that
197:45 growing into the poor system that starts porosity and permeability. Okay, so
197:51 is part of the risk here is what the demonization does to these.
197:56 the lime stones. And so what echo did was they went offshore.
198:02 . And so being offshore right the price of things goes right up
198:07 in terms of development. So their and and they shoot seismic and they
198:14 these low relief traps. So do oil field had 15 ft of structural
198:20 . Their traps had 100 ft of closure. Okay. And so then
198:26 had to figure out, well, the best ferocity? And in these
198:32 relief structures, how much is going yield hydrocarbon and how much is not
198:36 to yield hydrocarbon. Right? Can a waste zone. The stuff maybe
198:40 pregnant with with oil, but it's going to come out because there's not
198:44 structural push with 100 ft. So went offshore. They shot the
198:51 they identify the areas of better porosity pore porosity. They cord some of
198:56 stuff to evaluate. Right? And basically evaluated the faces with PNP
199:03 They ran capillary pressure analysis, which a tool we haven't talked about you
199:08 familiar with that. Right? It's injection that forces the oil out of
199:14 out of the rock. And they tell what pressure you would start forcing
199:18 stuff out. So they could know that oil is going to be yielded
199:22 a low relief trap or not. . So they they encountered obviously the
199:28 stones that look like this with, can see the process, the values
199:32 perm. They ran cap pressure on data and it would yield hydrocarbon for
199:36 ft of structural closure. Okay. question. Then they encountered what she
199:43 paxton or muddy grain stone faces. would not, I would not use
199:47 term. Okay, grain stone is supposed to have mud. Right?
199:52 what she calls muddy grain stones would what I call the low mud pack
199:56 . And what she called the pack , I would call the high mud
199:59 stones. Okay. And look at property values here, They could be
200:03 good. Right? And you can this up on logs and you may
200:07 on seismic. Right? But look the perm, right. The perm
200:10 to drop off and they get the pressure analysis on this stuff saturated,
200:16 it's not gonna come out. so waste some. And then even
200:21 more MMA critics stuff at the base the cycles still could have pretty good
200:25 , but the perms drop off you more. Again, this stuff would
200:28 way so, okay, I think can see where I'm headed here right
200:33 , with the structural trap and then of the Dolomites stuff uh, could
200:41 ferocity like we talked about right where stone gets replaced and the and the
200:45 grows in to the process of pore cement. Or you could have situations
200:51 this where the process is not as and but the permeability is still good
200:56 of the nature of that ferocity. , so I think you can see
201:00 I'm headed here, right? It out that the clean grain stone and
201:04 permeable dolomite would yield hydrocarbon in this relief structural trap. But none of
201:11 critics stuff would yield hydrocarbon. So when you look at these upward
201:17 sequences that make up that 100 foot structural closure, well, how much
201:22 it was grain stone impermeable dolomite? a lot compared to the more MMA
201:27 stuff. Right? And so they obviously very quickly that they're not going
201:32 make money here. Right? The relief traps don't have enough ferocity and
201:38 to yield enough hydrocarbon to make Most of it's a waste zone.
201:44 , so that's the first thing that out of the study, but really
201:47 I want you to appreciate is when modeled the porosity, office size
201:51 Right? And they try to identify offshore better porosity versus lower porosity,
201:58 ? They just assumed that the high would be really great reservoir quality,
202:03 you just saw that you could do you could, you could have my
202:07 stuff with good micro porosity and right? And conversely, some of
202:14 dola stones are associated with the dimmer here, where they only had like
202:19 ferocity but they had great permeability. would yield Haider curve. So that's
202:24 lesson to be learned. Right? not enough to know I have
202:27 You need to know what kind of it is. Right? The poor
202:31 because that's what governs the permeability. ? And again conversely, now you
202:38 that high porosity doesn't mean necessarily great ability. Okay, so those are
202:44 lessons to be learned. Right? so it's gonna be interesting interesting to
202:49 if three D. Seismic improves our to refine these porosity relationships.
202:55 Still always gonna come down to the data right? You've got to incorporate
202:59 rock data managers don't want to hear , but you've got to incorporate the
203:03 data to really understand what's going Okay, so seismic response Not proof
203:11 foolproof. All right. You need try and incorporate whatever length ology data
203:16 can to better understand the small scale and play relationships. What do you
203:22 in a more frontier basin where you have a lot of well controlled.
203:26 this is where you bring in the from the other case studies of comparable
203:30 . Right? And this is why weekend we're going to talk about play
203:35 with respect to location along based on platform transition with respect to strata graphic
203:43 that they provide the basis for the for interpreting seismic and more frontier
203:48 Okay, so you try to bring information and when you don't have nearby
203:54 controlled. Okay. Alright. Any or comments for today? So we're
204:03 we're gonna do a we're gonna have quiz next friday. Again, it's
204:09 be a very similar format to what guys experienced this week and uh it's
204:16 certainly the body of the test is to be devoted just to this
204:20 Okay. But the bonus questions could tied for the rest of everything we've
204:26 about up to this point in the . The bonus stuff. I don't
204:31 it to be easy. I want to be a little bit harder.
204:33 want you trying to see if you are grasping some of the concepts.
204:37 so the bonus stuff could cover stuff covered the first weekend or it could
204:41 this stuff this week. Okay. we'll just see. But All
204:47 So by monday I should be able send out some guidelines. Study guidelines
204:53 the second exam. Okay. And monday I think I should be able
204:57 get the test, return to you your grade and uh comments okay Or
205:05 test that has the results has my on it. Okay. I'll get
205:09 that. Okay. So any questions comments before we break for next until
205:15 friday? We'll see you guys next . Have a good weekend.
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