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GEOL6363 Carbonate Sedimentalogy - Day6 09-11-2021-Part1
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00:00 uh Yeah, yeah, okay. going to uh pick up where we
00:32 off yesterday, we started in on conventional uh carbonate play types. And
00:39 went through the platform margin ramp, grain stones, went through most of
00:43 examples. And then I got into last example, which I intended uh
00:48 you to see another pathway for creating depth in these limestone. So let
00:54 , since I just started in on , I'll just start back with some
00:57 the basic relationships and then show you timing relationships and maybe try to convince
01:03 that there's some fall control die genesis with this play as well. So
01:08 you recall our setting with the east salt basin and uh just to give
01:15 a feel for the lay of the here, I told you there's there's
01:17 sides to the base in here. west side is uh it's all dominated
01:24 . So every one of those yellow and you would sand body that's new
01:28 on a whole complex or the usual or the salt is withdrawn. But
01:34 salt was positive when the when the sands formed. And most of
01:39 most of those reservoirs are in the window, but they're a couple still
01:43 the old window. And then the famous side is this side here and
01:48 these old maps show sort of a seward sand body system, that's probably
01:53 the case, it's probably a series on echelon you would sand body
01:57 nobody's really worked out the geometry of sands. Most of these reservoirs
02:03 We're exxon's reservoirs back in the 70s and 80s. And they certainly
02:08 the coordinated to work this out, they never did. All right.
02:12 my involvement was more from the dye standpoint is one of my research projects
02:17 I did internally for Exxon, but this is like another little mm the
02:25 bodies succession that then the whole system down into another little sub basin to
02:30 east. All right. And I , you know that the sands of
02:36 graded up, they shall it up they programmed in a seabird direction on
02:41 eastern flank. And as they pro , they shoot the tempest sites out
02:45 front of it. That's very common see that in the lower, in
02:49 low relief ramp model. Um, showed you that the last saturday when
02:55 talked about the muscle cock in Germany the Germans documented that tempest tight
03:01 it's actually easier to shed material out the basin on a ramp profile than
03:06 is on a state margin profile because will happen with the state margin profiles
03:10 bypass and you don't connect this stuff , but on a ramp. This
03:14 can be actually physically connected. All . And then I mentioned the whole
03:20 is capped by the buzzer shale and controversy in the literature is what does
03:24 contact represent and the old literature and some of the stuff that's still being
03:29 today, believe it or not Treats top of the Haynesville as a Type
03:33 on conform to several on conformity. and the reason why Exxon did that
03:39 in the A. P. Memoir 27 on seismic photography is because
03:43 you look at the seismic lines, see what looks like the boxer shale
03:48 lapping the Haynesville, right? So took that typical online relationship to be
03:54 byproduct of drop in sea level. turns out that when applied moore's postdocs
04:01 a detailed log correlation study of the and she showed that the bugger actually
04:07 from the Mississippi ancestral Mississippi and it grades in to this area. And
04:14 what they were picking up is with parent on lap and seismic is actually
04:18 down lap as the boxer pro grades this area and then smothers and drowns
04:27 the Haynesville. So it's a drowning . Right? So I mentioned,
04:31 mentioned this relationship here with the It's down here in the sharp contact
04:37 you see at the top of the . But I meant I showed you
04:40 quarters yesterday just to make this point , you know, don't ever believe
04:46 that tells you that's a surface of real exposure from a straddle geometry,
04:51 ? And carbonates. You should be to prove that from the rock
04:55 All right. And this probably cost my job at Exxon, But I
05:02 the Tyler operating district who operated these ? I talked them into korean contacts
05:09 the border and uh, the Haynesville this is the proof, right.
05:14 that's a sub barrel, uh, conformity or not. Right? There's
05:17 curse there. There's no reddish Like we talked about. There's no
05:21 crust. Soul pies. Lights. fact, I mean, there's no
05:25 die genesis because the US is you're to see are already future by the
05:30 that they get dissolved out. this is uh, this is
05:35 these are drowning out conformity is all . And the neat thing about this
05:40 is wherever you find the politics and you find gas production. Right?
05:45 all of the sands, whether they're of the main show like this or
05:49 they're part of the tempest tight, , all of them develop identical styles
05:55 ferocity and all of them are gas with that one exception I mentioned yesterday
06:01 prospect that apparently got breached by some of fault cutting the trap.
06:06 So, and then the question what's the timing of the ferocity
06:13 Right. The again, the old treats us all as related to early
06:19 exposure and fresh water die genesis. , if that's the case,
06:25 why on this example from the other of the, of the base And
06:30 is from the west side in the window. Well, why don't you
06:33 early dissolution? Early calcite cement Right. You don't see any pre
06:38 segmentation. We've talked about the eu our future together. Like you see
06:43 , but there's no calcite cement between future in All right. And then
06:47 no micro ferocity development all in these . Alright. So this is while
06:52 still in the oil windows. So does that suggest? That suggests that
06:55 flu has created the porosity came after emplacement. Okay. Or after all
07:03 . And and you can see that know whenever there are some samples on
07:09 east flank of the of this trend the oil, not all of the
07:14 migrated out. Okay. And you still see the the oil is completely
07:21 . The primary porosity. And when look at the roads, there's no
07:25 ferocity. Alright. So that tells that the ferocity developed after the oil
07:30 generated. All right. And and the process, the only got developed
07:36 the oil migrated completely out right where completely in case wherever it completely in
07:41 the U. It's have protected it those later digex fluids. Right?
07:45 most of the Haynesville looks like you might have a little bit of
07:49 still stuck in the ferocity. The porosity. But where you don't have
07:53 encasement by the bitumen. Then you a secondary process. In other
07:58 you create process looks like this. right. So this is burial
08:02 All right. And this is one the first case studies that was documented
08:07 in the 80s. And it again bucks the Exxon sequence strata graphic model
08:13 the border. Because they want that be a major drop in sea
08:15 That's how they You look at their level curve. They put a major
08:20 at the at the end of Haynesville before booger deposition. Alright. But
08:26 is not early diagnosis, right? the grains are future. There's no
08:31 cement between the grains. Alright. there's other timing indicators here that tell
08:37 that this is all barrel die genesis of the some of the grain stones
08:42 skeletal material. Well, this is oyster fragment, anybody remember the mineralogy
08:46 oysters? They were cal siddiq, low mag calcite. Right. The
08:53 stable form of calcium carbonate. look at their micro bleached out.
08:58 right. What is this bright color ? That's a In the old days
09:01 the white paper technique, we used impregnate the thin section sample with not
09:07 the blue dye, but a blue spiked with the floor scene or fluorescent
09:13 . And then we look at it fluorescent lights. So that's plain
09:17 And this is with the fluorescent And you see all the bright color
09:20 , that's a reflection of the micro . Alright. And that that's
09:25 Right. Those things are not supposed leach in any diabetic environment, but
09:28 you see them dissolved out. And then look at the calcite cement
09:33 actually contain oil. So that tells that there was some calcite precipitation while
09:38 was still around in the water. then here's another very typical relationship.
09:44 are fractures. This has taken under fluorescence. Again, there's the micro
09:49 in the U. Ids. And here's the these are calcite cements.
09:53 . And and they're filled with what call dead or non fluorescent calcite.
09:58 look at the sharp contact between the ferocity and the and the poor filling
10:04 . If that microprocessor was there And you cut it with a fracture
10:09 start putting cement in the cement will into the adjacent ferocity, right?
10:14 be very, very uneven contact. those are razor sharp contacts. And
10:18 tells you that that process et developed that fracture was already cemented. So
10:24 consistent again with burial die genesis. . So, basically, my little
10:30 here is you start off with the would stand on the sea floor with
10:33 little bit of skeletal material ever. would sand has some skeletal material kind
10:38 germs and mollusc. All right. first thing that happens is this rock
10:44 gets progressively buried. It gets buried the realm of pressure solution and you
10:49 generating the burial calcite cements we talked , right. And what's the timing
10:54 again. Look at these calcite cements always distributed away from the future.
10:59 contact there never between the future So that tells you the cement developed
11:04 the initial pressure solution. All And then oil came in. So
11:10 a while this is an animal But then they will bled out most
11:14 them all bled out right. And left with a little bit of
11:18 And but you still have ferocity. then what happens? The next fluid
11:24 in some sort of acidic fluid. talk about what that could be in
11:26 minute. But the acid fluids come while this still has some porosity and
11:31 that generates the micro porosity. But what happens when we create secondary
11:37 ? What have we Always said, receptor die genesis? Right. When
11:42 lead somewhere in the rock, you're to put it back in the rock
11:46 else. So that secondary processes going do what? It's going to generate
11:50 calcite cement and you're going to evolve something like this. Okay. And
11:54 is basically what you see today. right. These are low permeability,
11:59 permeable reservoirs, one or 2 million of permeability that the grains are
12:05 Right. And so that microprocessors connected you don't need a lot of permeability
12:10 a gas reservoir. Okay. I , if this is an oil
12:14 this would be an issue, It would probably be charged with
12:17 but probably hardly any of it would out. Okay. Somebody appreciate the
12:22 relationships here. So this is you the implications. Now the flu fluids
12:28 nothing to do with the contact between bugger in the Haynesville. Alright.
12:34 fluids being moved up by some So the question is you know,
12:39 driving this dia genesis and uh I you I have a section and we're
12:45 to talk about this later this afternoon next friday. Get into a discussion
12:50 more detail about fall controlled diabetic plays are usually one of these other conventional
12:55 unconventional play types modified by deep seated basement faulting. And I think this
13:02 a this is another example of And the reason for that is that
13:06 only do we have the pyrite up the top of the hands? I
13:09 that's relatively early. Okay. Uh mean after the U. S.
13:13 already future. So, you and they're getting replaced by pirates.
13:16 know, that was burial. But lead, zinc and and sulfide
13:22 other sulphide mineralization all through the It's not just linked to the upper
13:27 of the of the Haynesville. And so these deposits like you see
13:33 these more massive uh ah iron sulfides a mixture of pyrite and Marcus
13:42 Now these two minerals are what we polymorphic minerals just like we call originated
13:47 polymorphic minerals. Right? They're the chemical composition have a different chemical
13:52 All right, but what is unique Marcus site? Iron sulfide? The
13:58 Marcus site can only precipitate from acid . So if you encounter Marcus site
14:04 your rocks, then you know, had to have an acidic fluid pass
14:08 those rocks. Well, what does fluid due to carbonate dissolves it?
14:12 . Yeah. Now pyrite is sort a C. D. C.
14:16 . It can it can it can for massive fluids but it can also
14:21 from basic fluids. So it's not unique indicator of the civic fluids.
14:27 what meant What other minerals are author forts? Right. These little diaper
14:33 diaper ram. It'll little crystals Double pointed crystals. Right. That's
14:40 a pathogenic ports that scattered all through Haynesville that only precipitates from massive
14:45 And then there's mega quarters that hears oyster again. And these bigger
14:51 Of course this is meg accords. . That is uh also an indicator
14:57 acid fluids. And more importantly, does Otha genic courts come from?
15:01 do the base metal sulphites come They come from frenetic basement rock?
15:07 ? There sourced from frenetic basement So you can start to see the
15:12 here. All right. And then mineral fluoride is also another relatively unique
15:17 mineral that indicates involvement of basement derived . Well, basement dry fluids are
15:25 or hydrothermal. Okay. And so heat helps drive the reaction to write
15:31 he always works in your favor for reactions. And so maybe I'm biased
15:39 , but I think you've got all elements for for fall controlled by
15:44 given that unique mineralogy that's mixed in these carbonates. And so I was
15:49 to take one of these fields, Overton. Overton is one of the
15:52 gas fields in his trend. And , maybe I'm biased here, but
15:57 sort of see some linear trends in of the better producing fabrics and or
16:03 producing wells. And you know, think if somebody shot some three D
16:09 , make sure they would probably see evidence for the reactivated basement faults.
16:14 I would argue that not only is Haynesville a good case study for barrel
16:19 on a grand scale that creates the quality, but it's also fault
16:25 Alright. And you can also make argument, I don't do you guys
16:28 we talked a little bit about uh thermo chemical sulfate reduction. This has
16:36 the elements of TSR. In the geochemistry of the iron sulfide supports
16:42 is a mechanism to drive this, the timing is after oil emplacement.
16:49 . And we actually see this a in the rock record where its transition
16:53 oil to gas seems to be a when you can crack off some acidic
16:59 whether it's related to T. Or not, that seems to be
17:03 pretty common association. So, so I'll be building on this later
17:09 afternoon, the next friday, this of the deep seated reactivated basement faults
17:14 driving carbonate die genesis. Alright. right. So for each of these
17:20 play types, I have a summary here, summary guidelines. And you'll
17:25 a lot of these points obviously repeated play type to play type. But
17:30 this play type, pre existing the topographic highs are critical,
17:36 You always want to pay attention to structural topography or deposition of topography that
17:41 created because during your next cycle of , you're going to take advantage of
17:45 highs and either put carbonate sands on of it or as we'll see later
17:51 reefs. Okay. And this point die genesis is applied to all the
17:57 types depth, the barrel digest history controlled reservoir quality. Historically the best
18:04 are those partially cemented grain stones or sands. Uh The latter being really
18:10 if you deeply buried this stuff, trying to hold on the ferocity.
18:15 , remember our relationship about the cyclist and the slope angle, right ST
18:20 platforms, you can't pro grade. you don't expect to see a lot
18:24 stacked reservoir units associated with the right? If they're if they're I
18:30 they're pro traditional geometries associated with the , you can still stack multiple
18:36 Alright vertically. But you can't pro a lot because the deep hole out
18:41 front. Whereas in a carbonate ramp I alluded to already. It's very
18:46 for this stuff to build out. ? And then back step and then
18:49 great out and then back step with little sea level rise and produce a
18:53 of multiple stacked reservoir units. Uh you need structuring to create a lateral
18:59 to seal off the edge of the bodies that they've been tilted. Any
19:04 Die Jack and strong graphic traps are common than people think. And I
19:09 more of those will be discovered if companies ever come back to Using three
19:14 seismic data and start chasing conventional plays . All right. Because I think
19:20 going to find that the conventional plays actually more economical than fracking these huge
19:26 big shale plays. But it will driven by economics. It always is
19:31 . So, and then the seals usually muddy. The critic there evaporated
19:37 actual faces. Source rocks are usually a problem because you're close to a
19:40 margin. Your source rock is Okay. And then I've just listed
19:45 bunch of examples. All right. you've got the detailed bibliography and the
19:51 is set up by these play Okay, So every every major play
19:55 has its own bibliography. And the is not set up in alphabetic
20:01 It's set up by data publication because And then this is self serving because
20:07 easy for me to add to the . Right? But actually I did
20:11 that way initially to just get you see the evolution of train of thought
20:16 ? To see how The old Some of these plays were discovered back
20:19 the 20s and 30s. Just to how the understanding has changed.
20:26 Because our understanding has changed. And what controls the occurrence and distribution of
20:31 sand bodies. All right. Shit All right. Any questions? All
20:40 . Well, that gets us to should be should have been the first
20:45 for today. And this would be second play type. So, we'll
20:49 through this and take another short But this would be the platform margin
20:54 play. All right. And of this only occurs in the steeper margin
20:58 to base in transition. You're not to see linear reefs associated with a
21:03 model. Okay. Remember that from modern if we had any reefs,
21:08 were isolated in front of paleo topography down ramp associated with salt tectonics or
21:16 other structural effect. All right. , we're just talking about steeper margin
21:21 . Now they don't they don't have be the bohemian Style of platform where
21:25 have an average slope angle of 45°. . I showed you an example of
21:30 from the Kapito in Mexico last saturday the slope angle had to be lower
21:36 that reef pro graded About 100 So, so, but I think
21:42 can see, you know, the of geometry that you develop depends on
21:46 slope angle. So if it's a style of reef deposition where the reef
21:53 along the platform margin and your whole really deep out here. You can't
21:58 grade, right? You're forced to vertically. And this is what I
22:02 a ribbon like geometry because it just the strike of the platform margin.
22:07 , In contrast that with something I said for the torpedo in Mexico,
22:11 lower cretaceous sequence, you lower the angle, then this this system can
22:17 . Okay, And you end up more of a sheet like geometry for
22:20 reefs. Now, you see the here of the seal relationship. You
22:26 to stop seal for these reefs. ? And trap the hydrocarbon in this
22:30 . The lower model, you're going piggy back over your platform interior
22:34 And if there, um, a , they're going to be effective top
22:38 . Okay, But in this what do you have to do?
22:44 have to drown out the reef, you? You have to deepen fast
22:49 to kill the reef and put either or deep water carbonate on top of
22:53 reef to give you an effective top . All right. So that's something
22:58 want to think about when you're risking play. All right now, we
23:03 a lot of time last weekend talking uh modern barry reefs would give you
23:08 feel for the setting some of the on reef deposition and how the reef
23:13 put together rights at any one point time, Basically to two parts the
23:19 front or reef core in orange, narrow. Right? And then the
23:26 lab or apron in front of it usually on open ocean when we're facing
23:32 , most of the shedding is back the reef. So the re flat
23:36 up being 10 or 20 times wider any one point in time. Then
23:42 reef front or corer. Okay, that was the answer to one of
23:47 questions, wasn't it? And then was the other question I asked about
23:52 segmentation effect. Where do you get marine segmentation Just up in the front
24:00 four slope or the reef core? never get any marine sedimentation back
24:05 Okay, so that was the answer that question. All right.
24:12 and of course, you know, talked about, you know how quickly
24:15 reefs secrete because they're very competent The corals grow quickly. But remember
24:21 don't just, they're not just dependent the growth of the corals because there's
24:25 battle between up building, getting whacked by a big storm and then taking
24:30 off again. But the net effect that these reefs are going to accumulate
24:35 quickly compared to everybody else around So you accentuate that topography create the
24:41 reach lagoon back here with the smaller larger scale patrick complexes. Yeah.
24:47 situation where you start. Mhm appreciate tradition. Well why why wouldn't you
24:57 storm influence? I mean, probably wouldn't have a great, you
25:07 wouldn't have really good reef development. don't know. That's a good
25:11 Um I mean they would grow and would go to sea level and then
25:21 if they could write depends on the angle, neither pro grade or they
25:26 that's the end of it. Right. So maybe I think um
25:40 there's another, there's another way perhaps to break up the reefs and a
25:45 talking about right, right, right the equator. Right. 5° on
25:49 side where there's no hurricane? And what do you get in
25:56 Just try so, well there are on the equator. But what's what's
26:02 external um catastrophic event you get in areas? No, not the
26:12 not the monsoons. It's, tsunami. So could tsunamis do the
26:18 thing that hurricane does. That's the . That's something that that's a big
26:24 that hasn't really been well answered People are still developing evaluating remember that
26:30 Sumatra, that earthquake and Sumatra in big tsunamis, it just didn't affect
26:36 . Remember went to went to um and what's, what's the island?
26:47 Uh huh. Yeah. No, tomorrow not the Maldives but the sri
26:55 , yeah, sorry Sri Lanka, had, they had tsunami effects
26:59 along the coastline of Sri Lanka to so people are studying that. But
27:05 don't think there any Reese right So it's mostly just beach erosion and
27:10 like that. So that's a good . That's something you want to think
27:16 . Right? When, whenever I wanna evaluate your setting,
27:20 If you're chasing reefs, you want know where you were in a relative
27:25 , right? Because this does impact the reef is put together and how
27:29 is rebel, how much is going be more institute all these reefs usually
27:35 pretty good seismic expression because of the off into deeper water. So that's
27:41 . These reefs have historically been easily on seismic. It's just a question
27:47 where you drill your initial will. . And where most companies drilled their
27:52 ? Well, they've drilled into the . Well, the apex could be
27:57 of the reefer. Could be actually of the back reef lagoon depending on
28:01 structuring. And so some of the is that maybe you're drilling into less
28:07 porosity uh either because it's more of critic or because it's marines cemented and
28:14 still may be co evil faces that good reservoir quality. Right? So
28:19 is an age old problem. His always want to drill the structural
28:25 right? Because I told you the day, they think they just assume
28:28 the whole structure is filled, filled oil to spill point. And that's
28:34 always the case. All right. , and then we have this discussion
28:39 this is the this is Dylan's. feel comfortable with this cross section
28:43 Right. So, uh but this what we rely on in the rock
28:48 to evaluate the maturity of our right? We're paying attention to whether
28:53 develop a reef crest and re We pay attention to the morphology of
28:58 organisms because they clue us into what of the reef trend that we've
29:02 All right. And then remember from discussion in the modern, showed you
29:07 for both of our moderate examples here . And then for great barrier
29:12 Remember these linear reef trends are always by channels. Alright. And this
29:17 really important in the subsurface because this one way to create a side
29:22 If you have a linear reef, is tilted any right? You've got
29:26 seal it off up, dip, in order to trap the hydrocarbon.
29:31 this is a great way to do . Take advantage of those channels.
29:35 , fill them in with deep water or shale. And otherwise you have
29:39 rely on a fault or something like to give you the the side seal
29:44 that linear, poorest reef trend. right. So let's just get right
29:49 some of these examples. And first is from western Canada. And this
29:54 a really complicated map view because it's apples and oranges here in terms of
30:00 styles. Uh, so you have all the reefs that you sent,
30:07 reefs that you see here are younger some of the reefs you see over
30:11 , basically what people call the shell . And this is a horrible
30:16 This is what should be called the like platform. All right. And
30:21 is the shallow water carbonate platform dropping into a little basin over here.
30:25 right. And along that margin, interestingly would have been the leeward
30:30 Okay, so here's an example of margin reefs. You have this linear
30:35 trend here called the rim be Meadowbrook and it extends up through Alberta to
30:42 northern part of Alberta. This actually a heavy oil province here. If
30:46 heard of the gross for Grossmont formation Canada, this is the carbonate equivalent
30:54 the oil sands that they currently All right, the plastic sands and
30:59 is a carbonate succession. That's a bit. This is devonian, a
31:02 bit older. And when the price oil was hi, everybody was looking
31:06 this as a, as they Right, But it's too deep to
31:11 surface mind. So they have to have to drill wells have to drill
31:16 wells like this. Right. They these saggy wells. Right? They
31:20 inject they steam and Jack down And then they, one of the
31:26 ways, I guess the upper one steam and Jack and then they let
31:30 oil loosens up and it collects down the other well bore and they pump
31:34 out. So, but that's And And they're not going to do
31:39 right now because the price of oil to be probably over $100 a
31:43 But anyway, this is this is of the typical oil province down
31:46 All right. And these are a of these linear reefs here. Most
31:51 these are dramatized, but there's still that are limestone. And whether limestone
31:56 we talked about the major reservoir units the reef core, which is this
32:02 . Your remember the thick, massive storm atop roids are the high energy
32:07 atop Rhode, right there in So these are buying stones to frame
32:13 they produced from primary porosity inter particle the grains and then a ton of
32:18 particle within the fragments. But the better reservoir quality is the associated Bakri
32:26 material which looks like this. All , smaller pieces of strom atop
32:30 The lighter grains here, a grain matrix. So these are roots,
32:34 and float stones and then finer grain that are highly productive. Right,
32:41 this is pretty typical when these fabrics still limestone. They haven't been altered
32:46 anything other than burial. Right? mean there's pressure solution is the indentation
32:50 , but there's no early die There's no demonization here. This is
32:55 production from primary porosity. All so that's Devonian. Let's just move
33:02 . Right. What happens at the of the Devonian major mass extinction?
33:06 storm atop rides seem to basically We evolved into the upper paleozoic Mississippi
33:13 through early permian, you don't have platform margin reefs because you don't have
33:18 right kind of organisms. Remember? the world of the baffle stone
33:23 The things that trap sediment crying woods bright zones and big benthic. Foraminifera
33:30 2-5. Not too bad fittings, Phil Lloyd Algae. Alright, So
33:37 not till you get to the upper . And then it's a Triassic that
33:41 have a return to some organisms that create more rigid platform margin refill
33:47 And now it's not corals and storm words. It's cal curious sponges and
33:52 cal curious algae. And then this organism I called tube affinities that nobody
33:59 what it is. Okay, but pretty clearly is a binder. All
34:05 . And then they disappear for the part. And then, yeah.
34:13 are they talked with us from the . No, they're talking about a
34:18 coral. Okay, True coral storm roads are not coral. Their coral
34:25 . Right. But they're not true . They're not hydro songs. Their
34:30 own family of storm atop words. right. And then in the
34:35 we come back in and start picking corals and stream atop a Reuters.
34:38 continue in the cretaceous. And then the Lord the middle part of the
34:43 . We start to see the route come in and the rudest dominate the
34:46 of recruiting patients reefs. All A long platform margin settings. So
34:51 just go through some more examples We'll start in the permian.
34:57 again, this is the, this west texas. And remember this.
35:01 was the this is the central basin . Okay, occurs in this position
35:08 . There's that channel. We're talking vacuum field. We talked about yesterday
35:12 right here. So this is midland over here. This is Delaware basin
35:16 here. And you can see up the north west shelf here, there
35:20 some lower Permian platform margin reefs that trend is called the abu reef
35:26 And it is uh, the big field is called Emperor Abo. And
35:32 can see the reserves are pretty relatively thick porosity. It's not incredibly
35:39 porosity, but it's a dramatized refill and debris. And so you're going
35:46 get some fractures superimposed on that to the permeability. So you see it's
35:52 by secondary porosity. A pretty good expression here. And you can see
35:57 interpretation here, the the marginal reef some of the debris and some of
36:01 stuff shut out in front of And most of the most of the
36:09 occurs from the upper part. For reason, companies have chased the upper
36:14 , but it's pretty good, pretty oil. So that works in your
36:17 to for getting oil out of the . So, this is what the
36:21 looks like for the This is the called oval tube affinity stolen bound
36:28 All right. And you can see of the secondary porosity developed here,
36:31 at this association again, between the and late stage and hydrates member of
36:37 story about the calcium rich fluids coming a dollar stone. So, I've
36:43 looked at this in any detail. are not. These are given to
36:47 by by somebody I taught a course that. They were operating the
36:53 So, but I bet there's some in my dissolution associated with this because
36:57 can see this is this is late and hydrates coming in after the
37:02 Right? And so it may play role in some of the secondary
37:07 And then the flanking faces also have quality here, the few cylinders and
37:12 noise. Remember down the ramp or protected settings. They don't want to
37:17 in a high energy environment. And I think clearly here you can see
37:23 of this course of buggy process. can see some solution enlargement along the
37:28 . So, again, I'm not at any thin sections of this.
37:32 to me, this looks like there some element of late secondary dissolution of
37:37 dramatized fabric as well. All But that's the permian. Alright.
37:44 then of course everything is sealed over these greenest shales, which is what
37:48 want for an effective top seal. ? Doesn't have to always be
37:52 It can be a dense McCready but in this case it's more of
37:56 shale. All right. Any questions the for men? And then you
38:04 up into the, into the You have a couple of trends in
38:09 texas. Uh when we talk about minute to start city reef trend right
38:15 , but an older trend here, Saigo. Remember we talked about Sligo
38:19 deposition in Louisiana yesterday for the grain . Well, that platform margin extends
38:26 south texas. And there is some economic gas production associated with parts of
38:33 trend. And the reason why it's is because it's really deeply buried.
38:37 15, ft of burial is still . So, it's got a little
38:42 of ferocity, but it doesn't have volumes of ferocity. And the model
38:48 was worked out way back in the 80s by people at the Bureau of
38:53 Geology in Austin is basically the typical platform margin reef margin model.
39:03 So, reef development along the margin then debris behind it. Okay.
39:08 then a restricted lagoon back here with isolated small scale patris, basically just
39:14 I showed you from the modern for . Okay. Yeah. And uh
39:20 the the organisms that are creating the energy part of the reef, our
39:26 storm atop roid and some robust All right. And then you see
39:31 are other rudest associated with some of back grief material. All right.
39:37 , this is the inferred reef crest re flat material. So, if
39:41 the case, this is a mature , right? It's built up the
39:43 level and then a more isolated lagoon here with little oyster banks. And
39:50 can see the acolytes. Right? , I wouldn't use the term title
39:55 for that. Alright. Acolytes or have nothing to do with tides member
40:00 only roll around during winter storms or occasional hurricane. All right. And
40:06 wouldn't be surprised if there who is in here. But I've not seen
40:09 really describe who is associated with this complex. But And again, remember
40:16 classical model is it's restored to its not the two together. Right.
40:20 you are in a strong trade wind system. So, it's possible that
40:23 could be some foods mixed in with reef, but it's not been described
40:27 literature. Alright. All right. then uh the steward city reef
40:33 That's a little bit younger in the . So instead of being lower cretaceous
40:37 more middle cretaceous again, this trend thought to extend around most of the
40:44 rim, although I doubt that it over here where the ancestral Mississippi river
40:50 right. You wouldn't expect that right be have a good barrier reef off
40:54 the delta, but certainly pick it again over here on this side.
41:00 this trend certainly extends into excuse into Mexico and we'll talk about that
41:07 in just a second. All So I don't know if this is
41:10 up at all if you look at questions of the treatments east or
41:16 But well, I always said three right? There can be a there
41:22 be a Northeast, there can be dewey's component, there can be a
41:25 component, There can be a southeast and I think the paleo geography.
41:30 And you'll see this in my next type. Good. The the orientation
41:36 some of these sand body systems associated plays suggest that the prevailing direction was
41:41 more out of the southeast, sort like it is today. Right.
41:45 just not as strong because we're further , but our prevailing winds today are
41:50 out of the southeast. Right, we're in the we're too far north
41:54 being a really strong easterly trade winds in the general easterly trade winds.
42:00 , okay, so that makes this what leeward with respect to the trade
42:04 , that makes this side all one with respect to the trade winds.
42:09 again, if you go back to middle cretaceous, This is about 15°
42:14 of the equator right through here. that puts you in the heart.
42:17 strong easterly trade wind built. All . Is that a double?
42:24 it's an offshore isolated carbonate platform. solar. Mhm. Associate with the
42:31 . Yes, this outcrops today. right. So there's no production because
42:35 is outcrop built. This was lifted by the formation of the sierra madre
42:41 . Right. The big the mexican , right, continuation of the US
42:48 down into Mexico. All right. right. So, we're the Edwards
42:55 also called the Stuart city reef trend part of the people also break out
43:02 a glen rose, but principally the . And then the whole thing is
43:05 out by the Georgetown. Georgetown is pelagic carbonate that looks a lot like
43:10 eagle furred in core or since Alright. And it's it's interesting to
43:17 at the relationship between the Sligo and Edwards because you would think if you
43:22 topography and the Edwards. Right. sorry. In the Sligo, where
43:27 you expect to stack up your next system in the same position.
43:31 Yeah. Well, that happens when sit on continental crust. Right,
43:39 this is this is there is the of uplift. We talked about
43:43 And then this is what's called the Marcus arch in south texas. This
43:46 a structural extension off of off of land to uplift. And everybody thinks
43:52 is a continuation of of Grenet IQ crust. Okay, Because there's no
43:58 tectonics associated. No final assault under on the san Marcus arch.
44:04 But when you go north or northeast southwest of the of this area
44:11 you get salt tectonics. Alright. look what happens to the two
44:16 Right? The Sligo stays outboard and Edwards goes more imported, bifurcate.
44:24 right. And it actually does the thing up to the northeast during it
44:29 . Nobody knows for sure why. I mean, the logical, I
44:34 , the only thing that changes is tectonics. Right? So maybe maybe
44:38 salt tectonics has something to do with ? Why you get this bifurcation
44:42 All right. I don't know. knows the answer, but,
44:47 Mhm. Salt pressure. Mhm. would you would back step your reef
44:56 that older topography further landward. There's there's a lot of salt tectonics
45:03 through this part of south texas, not right here. Okay. So
45:09 the salt has something to do with . All right. And then you
45:13 see you see the map here with linear producing trend. The red is
45:17 Edwards. I just want you to . They've listed a bunch of fields
45:21 and it all looks like these fields associated with the platform margin reef.
45:26 the two biggest gas fields are not with the platform margin Dilworth field here
45:32 word field here are different play They are back grief. Laguna carbonates
45:37 underwent favorable secondary porosity. So the platform margin reefs that you see here
45:44 this diagram is funny, right? and most of these worlds shell discoveries
45:50 in the 50s and 60s, shell everything vertically, right? Nobody factor
45:57 horizontal drilling back then. And then course, Shell walked away from the
46:02 back in the late 70s, early and they sold these off to the
46:07 companies and I think pioneer now owns . But they have not. They
46:14 have tried to sell Ponti for all know when they got when they decided
46:17 put all their eggs in the But so I'm not sure who owns
46:23 right now, to be honest, these reasons now are not, are
46:30 dominated by coral storm atop. Roids dominated by routers. So remember rudest
46:34 bivalves and they're essentially five types of that come into play here. Some
46:40 big as my fist, some as as my leg. All right.
46:46 some are magnetic. And some were Siddiq. And somehow that the schizophrenic
46:52 . Right? One layer of one layer. A Reaganite. All
46:57 . So the big robust forms are critters right here. The to print
47:04 , right. They have a lot internal primary process. They have a
47:07 of process in their shell structure and then mono purists or the little fist
47:14 ones. They are more protected settings like oysters. They like to live
47:18 more protected settings or cal citic. then the two casa, that little
47:23 shaped Is the schizophrenic one, That had the dual layer of calcium
47:28 . I it's like I couldn't make his mind how to grow and it
47:32 make up its mind how to what precipitate in a skeleton. Alright,
47:39 the model for the rudest reef complexes the platform margin is a little bit
47:46 . All right. It's not a barrier reef model to start with.
47:51 , it's actually a series of patriots that kick off along the platform
47:59 Right? So little reef core of of Brutus and rudest or what baffler
48:06 . Right? They either grow like and then when they die they just
48:10 over or they grew on the sea , flat line. But trapping
48:15 Okay. And then what happens when big storms come through? They easily
48:20 by erosion, they easily break this up and generate debris. They generate
48:25 grain, stone debris. Right? could be float stone, roof,
48:29 , depending on big pieces are And create a halo effect around those patch
48:34 . And then what happens to these patrick's? They end up coalescing right
48:39 what now people map is all in brief trend. Okay, so everybody
48:44 what I'm saying. So then start as a barrier reef. They start
48:47 as isolated little patriots and then they into what now people map is a
48:53 reef trend. All right. And of that debris built up the sea
48:56 . So you gotta re flat and you get a battery for going behind
48:59 . All right. So that's not . But you can see these relationships
49:04 outcrop and in the core. So crop this example from Mexico. This
49:09 that part of the reef trend that ? You see the big holes
49:13 Well, those used to be large of the components which are a
49:18 they've been dissolved out. And then the matrix? The matrix is
49:22 The critic fabric here is the equivalent the subsurface. They're the complainants with
49:27 internal porosity. And then there's some matrix, right? With fine little
49:33 material and then this dark and light here. That's one of the two
49:38 IDs, the schizophrenic Rudy's we were about. So, you see the
49:43 here, you can generate ferocity. . And I've had clients. I've
49:48 clients drill this stuff where the logs great ferocity again. All right,
49:53 what is it isolated mold over isolated mold over here, isolated mold
49:59 here? No permeability. So, the reef course are not great producers
50:05 of that problem. It's to my , the good reservoirs are the debris
50:11 that accumulate between these patrick complexes. right. And so here's the outcrop
50:17 uh near belt in texas. You a patrick over here. You see
50:21 patrick over here. And then here the rippled sands between it. And
50:26 at the ripples here, those are oscillation ripples, right, symmetrical
50:31 So, this has created by wave . All right, storms break it
50:37 . But then wave energy reworks And then here's the equivalent in the
50:42 . Alright, definer debris here of rudest. This is a grain
50:47 The rude stone fabric, a mixture secondary porosity. So any anything anywhere
50:55 buggy or modified inter particle porosity to of molding ferocity. Right? Because
51:01 lot of oregano, thick material in rocks, some primary intra particle
51:08 but not great reservoir quality. Look at the look at the numbers
51:11 , that's for sample from 10,300 ft porosity, which is good. But
51:20 at the Perms 2.4. But I mean, those aren't bad perms
51:24 gas reservoir. Okay. And, know, the problem shell had was
51:31 were drilling vertical wells. Right. then what would happen? They would
51:36 would start sucking up water. They would water out these wells.
51:40 . So they if they got one two million cubic feet of gas
51:45 that was considered to be a good . All right. And because of
51:49 low permeability, how do people end characterizing this reservoir? They called a
51:54 reservoir because of little perms. Oh got to be fractured. And this
51:59 the mentality for going horizontal. So when pawnee was bought by Pioneer
52:05 in the back in the I forget Early to mid 2000s, Okay,
52:15 , skipping ahead. When when Ponty in. Well what did they
52:21 They went horizontal, right. They they would intersect lots of fractures and
52:26 did and they did get gas production . I mean look at the rights
52:30 , the rates went from one or million cubic feet of gas a day
52:35 shell had To an average of 8-10 cubic feet of gas today. All
52:43 . Oh for well. Right. I knew I I know this because
52:48 my brother in law who just unfortunately passed away a couple of months
52:54 lives in south, he lived in texas. He had a ranch in
52:57 texas and he had, his ranch over pawnee field. Right? So
53:02 in the mid 2000s, what was price of gas? 8 to $10
53:06 M. C. F. I it was incredible and he was just
53:10 was loving it man. He's getting huge checks every month. You
53:13 he's going out to the wells side he's telling me what the rates
53:18 That's great until it dropped off. , The downturn in 2008. That
53:25 the end of that. All Yeah. And then but fortunately he
53:30 up some eagle for production later. ? Because all the companies came in
53:33 they went down and started chasing the furred instead of the Edwards. So
53:37 uh So he did okay. Um right. So, obviously they produce
53:42 lot more gas, but they also drilled a lot more wells to but
53:46 , the wells were better in terms productivity, the surface area not necessarily
53:53 . Yeah, Well, I think supposed I think it well, fractures
54:01 hurt. Right? But again, is a misnomer about low permeability,
54:08 is right. Everybody thinks they have be fractured. But when you look
54:12 the course through these, through these , you don't see a lot of
54:15 . You never see a lot of , which is sort of always bothered
54:20 a little bit. All right. . Yeah, production stay with
54:30 Well, you're not going to see fractures, right? You're fractures are
54:34 going to be horizontal unless they're Alright. Didn't we have this
54:40 right, fractures, fractures are because your principal stress direction is top
54:45 bottom. Right? So, you up with fractures oriented that way.
54:51 would think somewhere you when you core fields and you see more fractures than
54:56 see, it's just it's always I know, it's just been my experience
55:01 I'm gonna talk about the austin chalk today. It's the same with the
55:05 chalk. Everybody thinks it's a fractured . But darn you just don't see
55:10 many fractures in the subsurface and all core that's been collected. I
55:16 actually, Right, Well, that's saying it's fractured because of the low
55:26 permeability is right. When people see or two mila darcy's, they just
55:31 that you've got to have fractured Who? Well, well, I
55:41 you the Haynesville where the jews are and micro porous. And I said
55:47 was good enough. That was 1-2 supermen ability. And that was good
55:50 to get the gas out there and no evidence for that trend. The
55:55 are part of the production. I mean, what is the normal
56:02 if you have fracture assisted production, get the gusher rates right within the
56:09 few weeks or a few months of . And then what happens? Rapid
56:14 ? Long term, lower stabilized All right. So, that's how
56:18 would tell whether fractures are involved or . You don't see that for the
56:24 . And to be honest, I mean, I don't know for
56:26 But to be honest, I haven't anybody show the gusher rates rapid
56:31 Long term lower stabilized production for All right. I think. I
56:39 the beauty of a horizontal. is you're accessing a lot more
56:42 Right? So you should get a more production whether they're fractures there or
56:47 . Right. But and this is mindset about fractures, right? Everybody
56:54 the low perm carbonate rock fractured. just what they do. All
56:59 That's what the engineers do, I . And they're the ones that sort
57:02 control the they control the purse string the strategies for developing some of these
57:09 . So, okay, everybody. that's another plate type. So,
57:14 are the rudest, right? And rudest continue up into the upper
57:18 And then they die off at the of the cretaceous, right? Probably
57:22 the K. T. Boundary. um one last example here related to
57:30 stirred city reef trend is this offshore the platform called the Golden lane
57:36 And this is an interesting play because not only production from platform margin,
57:43 reef complexes, but its production on leeward margin. Alright. Which sort
57:48 bucks the trend. And it's also curse modified. Alright, So it's
57:52 this is one of those curse modified . So here's the map for golden
57:58 . And you can see the this situated on an offshore paleo high paleo
58:03 , frenetic basement high. But you all these producing fields here in
58:10 This is all strung together to call Golden lane field. All right.
58:15 , you see the reserves are over billion barrels of oil. I
58:17 this is this is discovered back in early 1900s, like 1905, All
58:24 . And uh, but the production think is pretty clearly impacted by tertiary
58:30 certification because what happened in the tertiary , you see this off shore frenetic
58:38 high, that's the paleo topography that up the elaborate platform and you actually
58:43 briefs on both sides. Okay, is reef over here. There is
58:48 over here. You can see there's little bit of production on that
58:51 But the reason why there is not production is, I think P max
58:55 that it's tilted so much that all rest are in the water lake.
59:00 . They're not in the, they're in the oil like All right.
59:05 , and so that's why you get preference of production up here because of
59:09 tilting to the northwest. It's also structural tilting that sought to expose some
59:14 the platform for a while to car . All right. And so here's
59:20 of the seismic that supposedly shows some the cars defects along the leeward
59:26 All right. The production is from a labra limestone, which is the
59:33 and the massive limestone is the rudest complexes. All right. And look
59:38 the numbers here. I mean, only do they have more than two
59:42 barrels of oil in place, but initial IPs for some of those wells
59:46 still the record IPs for any producing rock Over 260,000 barrels of oil a
59:54 . All right. And the famous blew out all right and it blew
60:00 stalactites and it blew out the lag . This is documented in the
60:05 Okay. That's the evidence. Of modification. Right. What did you
60:11 to create? You have to create cavernous, had to create cavernous proxy
60:15 . We're still like Tyson stalagmites and some of that stuff blew out and
60:20 the hearsay and Pemex. This has carried through now for well over 100
60:25 . Is that not only did the and stalagmites blowout, But 60 ft
60:32 drill string broke off, turned upside and came out the whole like
60:38 Okay. I was told this when was a grad student at Rice,
60:43 advisor was change lee Wilson and he a long term relationship with Pemex.
60:49 was fluent in spanish, did a of fieldwork in Northern Mexico and he
60:53 me was a grad student, Pemex, that's what they say.
60:57 60 ft a drill string broke off came up upside down, came out
61:01 down. So when I talk that taught a course for pemex back in
61:06 13 I guess or 2014, I remember. But I went down to
61:12 Villa Hermosa area, which is not far from offshore Golden lane and
61:19 When I got to the slide a couple of Alzheimer's in the
61:23 Of course they weren't that all right they live back in the early
61:26 but these guys are in their fifties sixties and they, and I asked
61:30 specifically, have you guys heard of ? They said, yeah, this
61:33 what's been carried through in Pemex for 100 years. So it's a curse
61:38 platform, margin, rudest replay. . Which accounts for the high production
61:44 and obviously the high reserves. All . Yeah, objective itself lot
61:52 Yeah, Well, it's, I'm sure they under they understand they're just
61:58 the ferocity office seismic. I so the reef is certainly chorus
62:03 The question is how much of the brief debris is Kearse modified.
62:11 I mean, you know, that's old trend. I'm sure there toward
62:14 end of the leg here in terms their production. In fact, I'm
62:17 even sure they're still producing to be . But but the intrigue for
62:24 the intriguing thing is we've got, got this at all like lagoon,
62:29 tall like structure. Right. And can see, you can see the
62:32 shell looked at this when they did regional evaluation of the Edwards trend around
62:37 gulf rim. They viewed this as , as a a tall reef
62:41 Right? With refund east side and the west side structurally tilted like
62:47 Okay. And, and I don't there's any question that you would have
62:52 reef on this side, because that's open ocean side. It was also
62:56 strong easterly trade wind side. And trade winds accentuate these reefs.
63:01 . They help develop the reefs even . But why would you get released
63:05 here on the leeward side? This is a side where they should
63:08 got shot in the back by their lagoon. All sediment. They should
63:12 never developed any great thicknesses that they pretty good. So, what's going
63:17 here? All right. Well, first implication is is that the lagoon
63:23 to be relatively deep to inhibit off transportation. All right. So,
63:27 showed you some of that seismic data seismic data was evaluated by the Bureau
63:33 Austin. Right. The Bureau of Geology. And I've talked to those
63:38 and they told me they think from seismic and I'm not sure how you
63:43 resolve this, but they told me thought the lagoon was about 100 m
63:47 water depth, sort of like some the present day lagoons are off of
63:51 today on those offshore satellite brief I don't think it has to be
63:57 deep to inhibit. I think if were 30 or 40 ft of water
64:00 back here, that would probably be to inhibit off bank sediment transportation.
64:05 right. So that's why the reefs . But what else helped them thrive
64:11 trade winds. Right, Because the winds would not only affect this reef
64:14 , but they would blow back here provide agitation. Right? And that's
64:19 to help the re screw. And evidence for that is when you look
64:22 the back reach settlement And this is this is a picture I cropped out
64:26 an old paper published back in They described who is occurring in the
64:32 resetting. And this never made any with when people just had the northern
64:39 moloch, right? It was either or goods, but not one and
64:43 not reefs. And then it was it. Right. That never made
64:46 sense. But it makes sense. you think about the trade winds.
64:50 , so the debris is not generated the trade winds. The debris is
64:55 by big storms. Okay, But that sand is accumulated, what will
65:00 trade winds do? They will take skull sand and start converting it to
65:04 lot of sand. Okay, And that's the evidence here that the trade
65:08 played a role in this reef Alright, I'm going to develop the
65:13 later. You're going to see the winds also shed sand off the edge
65:17 . That's another plate type. We'll about later. All right. That's
65:21 poza rica. Yes. Okay. right. And then just to finish
65:27 here and we'll take a little break . What's one of the risk here
65:31 the state margin platform margin reef you you have oceanic swells hitting up
65:37 these reefs, right Against the framework the Upper four slope. You're going
65:41 pass a lot of water through that fabric. Right. And that's going
65:47 lead to some degree of marine So one of the risk is that
65:51 going to be some degree of marine in the re front or the upper
65:55 force load. But as I never in the re flat and never
65:59 the back reef lagoon. All All right. But the famous example
66:04 where marines imitation came into play is Permian reef complex in west texas.
66:08 right. And our crop, These lost basically 90% of their ferocity on
66:15 sea floor by marine sedimentation. There there's the Marines Imitation. Remember
66:21 are the two. These are the sponges, sometimes as tube affinities that
66:26 a frame framework. Remember these cements cloudy, light brown cements radio
66:34 Right. A reaganite to begin Look, we're Sopra city, there's
66:39 any porosity in this rock. All , little bit, but not very
66:43 . All right. And so something this. Lost it. All
66:46 On the sea floor. Now, good news is most reefs don't lose
66:50 much ferocity, but you expect them lose some degree. Okay. And
66:55 want to risk that into your So, remember my point if you
66:59 to choose between the reef core and battery flat for good reservoir quality.
67:06 is what you want, right? re flat. You want to That's
67:10 your best chance of finding the best quality. Also easier to finance.
67:17 . But again, a lot of drill that inflection point, right?
67:20 they drill the top of the If they hit the reef, if
67:23 hit the reef margin, they may into something that looks like this.
67:27 right. And then they think the place condemned because they don't understand
67:33 Just move slightly. Land where his sealing against. Yes. And and
67:40 on the other side. Right. . I think Pemex missed the play
67:47 . Okay. For that reason. . Not not because the marines
67:52 but because of the structural tilting, ? My my sense from, from
67:58 there was they've given up on these . They think they're all water
68:03 And I think what did I say reefs that face open ocean, They
68:07 more debris behind it, right? have a good re flat developed.
68:11 think there's a play back here in re flat where it's structurally tilted and
68:16 pinches out against the laguna carbonate. ? But they were down here with
68:21 the reef right? And not the flat. What is my job to
68:26 him what to do? And I say anything. But I think I
68:30 they missed the play there. Alright. So marines invitations something you
68:38 to factor in. And then the point is dole amortization comes into
68:42 especially in the paleozoic where these uh margin res front a deeper bass and
68:48 either with shale or evaporates or are carbonates. What was that? Dolomite
68:53 we talked about based on the Right. So almost always people will
68:59 the basically the watering model here and where you see preferential demonization of the
69:05 margin. Okay. And the beauty doing that. Whatever the timing of
69:10 of the whatever the mechanism is, you can dull monetize this fabric,
69:15 reef is going to fracture to a degree. Right? That's Dulles,
69:19 are going to fracture to a greater . And then what's going to happen
69:23 the debris sheets behind it member to about the pollen model or by model
69:30 . The dolomite goes after the finer . In this case of carbonate
69:35 political sand dramatizes it replaces it. then what do you do later Remember
69:42 70, by volume Dolomite story, reach out the remaining parasitic grains If
69:48 touching a 3D. Which is the of a rude stone, Then you
69:52 up with these kinds of permeability is - five Darcy's of permeability.
69:59 Beautiful relationship. All right. Here's summary again, Reese want to take
70:06 high grounds when they can find All right. One thing you need
70:09 keep in mind is the age of reef complexes you're dealing with because the
70:14 controls who the players were and what starting in neurology was. All
70:18 What's the general rule of thumb? little lower paleozoic reefs are more cal
70:24 . So they don't have as much porosity in lime stones. Right?
70:27 you don't have as much a And then when you get into the
70:31 and tertiary, a lot more regulated . Right? All of our corals
70:34 rare genetic. So, you see lot more secondary porosity in those younger
70:38 systems. Same point about reservoir We mentioned the structuring sometimes required to
70:44 a lateral seal. Uh The most seals. Top seals are usually the
70:52 , deep marine carbonates. Your sales drown out the reef and you you
70:56 them in that uh impermeable material. , But again, if they can
71:01 grade and you have a muddy lagoon it, you'll end up with a
71:05 lagoon sitting on top of the reef pro gradation that can be effective.
71:09 seal source rocks are usually not a . Right? You're close to the
71:13 margin. Again. All right. questions about that, Why don't we
71:21 about uh 10 minute break here and start back up at 11:15 Go for
71:28 45 minutes and break for lunch. . Okay, so you tie I
71:48 I stopped this recording so we can that and well, got
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