VideoPoints

• ••• • •• • ••••• • •
GEOL6380 Sequence Stratigraphy - Day2 PM 04-23-2022
Help Tour
© Distribution of this video is restricted by its owner
Transcript ×
Auto highlight
Font-size
00:24 mm hmm. Okay. We can about about seismic photography leaving off where
00:37 left before lunch. And one of here's an example of a seismic
00:49 You can see in the image behind . And one of the fundamental breakthroughs
00:56 in interpretation of seismic data was statements by the excellent research group that seismic
01:05 are assumed to image betting surfaces. because you're imaging the beds when one
01:15 terminates against another, if you see identified by the terminations of reflections,
01:22 we call lap out. The assumption that that's imaging a basic termination or
01:29 out of the geology. We've already the idea of a lap out Looking
01:33 great balls. Work back in 1909 the identification of of reflection terminations that
01:42 be consistently identified and correlated on seismic . That's the idea of de positional
01:50 which our bodies of relatively confirmable banner brian conformity and their arc relative
01:55 ease identified within seismic data. One I always remind students of is that
02:02 data, there are various kinds of , The kind of conventional spectator that
02:07 get in the oil business Is typically to 100 m. It does keep
02:14 better all the time. Uh, know, marine seismic is usually better
02:18 the land seismic. But you the quality of seismic data can certainly
02:26 so In 1977, Valladolid said that sergeant reflections are generated by stressful surfaces
02:35 are Krone strata graphic rather than by of arbitrarily defined little strata graphic
02:43 Okay, now, I know I a long time to explain this one
02:50 from Pete bail. It took me long time to understand what he meant
02:55 Arbitrarily defined little strata graphic units. . I don't really know what he
03:01 in 1977 when I read that Now I know exactly meant. It
03:07 it was the decisions by wheeler and to draw vertical arbitrary cutoffs that we
03:18 to define formations where there was into going on. As I just
03:24 So what Peter is saying is that arbitrary boundaries, whether they're vertical boundaries
03:30 she's um lines do not generate straddle and are not what the seismic reflections
03:39 he says no they see surfaces which chronic strata graphic significance and they have
03:44 to do with these faces boundaries and vertical boundaries that we learned. And
03:51 folks were using to define little Now what's interesting is Bill Dickinson,
03:58 passed away was an interesting guy. saw him give a few talks
04:04 He's kind of the grandfather of the graphic analysis of sand stones in the
04:09 of tectonic origin. And he wrote paper as the editor of the american
04:16 Science called The Place and Power of and geoscience. And he made the
04:20 that the conclusion that seismic reflectors of traffic traffic horizons is clearly untenable in
04:26 literal sense. So just to make understand this in 2003. Right?
04:33 know, Bill Dickinson was part of Arizona U. C. L.
04:36 . Crowd that I criticised in the lecture is directly contradicting a statement that
04:43 made in 1977, directly contradicting The question is, how can they
04:48 be right? Is it true that can have seismic reflectors that are that
04:55 not Chronos strata graphic or or that chronic strata graphic. Dickinson clearly says
05:00 , there's no way that these seismic interestingly Houston word reflect reflectors. That
05:07 the underlying geology off which the sound bounce versus the reflections, which is
05:13 you actually see in a size And if you take to any geophysicist
05:18 at the University of Houston, you'll taught to understand the difference between the
05:23 which is like the mirror, You , the actual glass versus the
05:28 which is the image of yourself. see in the glass one is an
05:32 of underlying geological reality. Mhm. , I'm going to deeply criticize Dickinson's
05:42 because I don't think he knows what knew or knows he's passed away.
05:46 don't think he had a clue what was talking about. And the reason
05:50 unlike Dickinson, I've done basic training seismic interpretation including understand how data required
05:59 processed. I'm going to review that quickly for you. If some of
06:03 will be a review, perhaps it be new for a few of
06:06 But it's a good review of the principles of seismic data. So here's
06:13 pretty standard explanation. We have a column on the left with a
06:21 shale, sandstone, shale, sandstone, maybe an evaporator, volcanic
06:28 . And then another sandstone. And and then we have the acoustic impedance
06:34 is basically the a measure of the through which sound travels through these various
06:41 . So the sound goes through the . Then it slows down as it
06:46 the shale. It speeds up when hits the sandstone. And you notice
06:50 the that the velocity of of of B versus sandstone A. Is a
06:59 faster. Okay. And that's because buried a bit more deeply. Then
07:06 sound waves go into another shale, know, this shale? We'll call
07:10 shale to than that shale one is , it's a little faster than that
07:15 , but it's slower than the Then we go into limestone, limestone
07:19 pretty dense, so the velocity is higher. Right? The acoustics and
07:24 would be typically microseconds per foot or . So that's basically the vast velocity
07:34 , time divided by distance. Then goes through the sandstone and again,
07:39 slow, but not quite as slow the shale anymore. So the rocks
07:43 getting deeper as they get buried. it goes into this extremely fast
07:49 right? That could be sold. that could be a volcanic rocks very
07:52 . Then it goes into the Now, um then on the on
07:59 column here we have the reflection Okay, when you go from fast
08:03 slow, you get a negative reflection coefficient. Then he goes from slow
08:09 fast. You get a positive reflection . Back to slow, you get
08:15 negative reflection coefficient, get the you get a positive reflection coefficient because
08:21 velocity contrast is higher. The reflectivity that service is greater in which the
08:27 the velocity contrast or density between the , the more the energy is reflected
08:31 versus passed through already given wavelength, energy moves through the layers and some
08:38 reflected back. We're primarily interested on on the on the sound that's reflected
08:43 because that's what we read at the at the surface. There we go
08:48 the sandstone. Once again, we a negative negative reflection. Then we
08:52 our evaporate later, we get a strong reflection and then we're back in
08:57 sandstone, we get a negative Okay, and we can take the
09:02 coefficient and turn that into a basically sort of reflectivity function, which is
09:08 is the mirror that's going to reflect sound back now, this is the
09:15 . Okay, so it's got the low and it's got the main peak
09:22 then it's got some sidelined again. , okay, we're not going to
09:26 into the into the phase of the in some seismic data, the reflector
09:30 in the middle of the of the Sign Terms, It's zero Crossing.
09:35 not gonna worry about that too Okay, but at any rate,
09:39 the shape of the waiver that you into the ground. Okay. The
09:45 is what happens that wavelength when it these relative when it hits these reflective
09:50 surfaces, the reflectors. So this is passing through the earth, then
09:56 hits that reflector which is negative. it takes that wavelet and inverts
10:02 There it is. Okay, so has the same shape as what we
10:07 in. But it's reversed just like a mirror image. Then that hits
10:13 positive reflector and then we get back reflection and then we get back the
10:17 that we started with. So there is back to what we started then
10:22 hit a negative another negative reflection. once again the wavelet is reversed.
10:28 we hit this very reflective surface and get the wave of the back.
10:32 now it's enhanced. A little bit energy is coming back. Then it's
10:36 through that boundary because it's like a shiny mirror. Then we hit that
10:42 negative reflection coefficient. Once again, invert our wavelength. So it's the
10:48 of what we shoot in. Then get this very strong reflection coefficient and
10:52 get the wave look back at the and then we get the last negative
10:57 and once again the wavelet is Now recognize we actually lose energy as
11:03 go into the round ground because you , some of the energy is passing
11:07 some of its reflected back. So can look at the size with trace
11:14 you can understand it's basically that that that we shoot into the ground that's
11:19 returned reversed or or the same was shot into it and it just depends
11:24 the reflectivity, positive or negative and strength of the reflectivity of the reflectors
11:29 accounts, which basically is a function the impedance contrast. But the velocity
11:34 between the various layers, that makes . Just a pretty basic explanation of
11:42 a seismic trace versus the geology that reflecting off. Okay, so here's
11:50 real data. So here we've got sonic log, so that's a measure
11:54 the impedance contrast of the rocks. , there is the density log which
12:01 matches the sonic log and then this the acoustic impedance, which basically is
12:05 reflectivity. Okay, And every every you see a sharp contact, you're
12:10 to get, you're going to get sharp a contract. There is the
12:15 that we show through. This is zero phase wavelet, which means that
12:20 reflector is going to be smack in middle of that trough there. We've
12:24 a couple of side loads, And that's the you can get the
12:27 like the frequency of the pulse that shoot into the ground. Okay,
12:33 here we've got slow rock. Then got fast rock to get a reflection
12:40 . We get back we put in it's a fairly weak reflection coefficient.
12:43 we don't, most energy passes Okay, then we hit this one
12:50 and again, it's it's slow to . So there's a slow to fast
12:55 . Looks pretty well what we shot the ground. We also get a
12:59 coefficient off the base of hair. . And that's kind of interfering with
13:03 upper reflection. So we've got some there and then we hit the base
13:08 that unit. It goes from fast slow. And of course, because
13:11 the huge contrast, we get a of our energy back. So we
13:15 the reverse of what we shot on ground. Now that's a synthetic
13:20 So that says we know what what shape of the wave letters that we
13:24 into the ground. And you've you've of the I don't know how it's
13:29 . You are with the University of . But the the the the Society
13:33 Exploration Geophysics Club at the University of calls themselves the scG wavelengths. And
13:39 referring to this thing that you shoot the ground. Now on the left
13:44 the left hand side, we have actual trace. So you can extract
13:47 vertical trace from the well. So seismic trace that's in the position of
13:53 well and what you can do with sunsets that the so this is a
14:00 seismic based on convulsing your input pulse the acoustic log. And then you
14:06 compare that with the real data. so you can see that that reflection
14:11 that reflection and that reflection all show very well. Um and you know
14:21 reflection here that doesn't show up that muted. And uh you know there's
14:26 reflections up here that that don't seem show up in the seismic on the
14:30 trace. Maybe there's a bit of in here. But anyway, this
14:33 you to take your well log produces trace and then tie the geological contacts
14:39 the well log directly to your seismic . Okay. And of course,
14:44 know the depth of the log, know the two way travel time.
14:48 you can integrate those two knowing the of the rocks. And then you
14:51 start to depth migrate your seismic line making the seismic to. Well long
14:57 . I'm not gonna talk anymore about . That's a pretty traditional process of
15:02 and tying well log data misogynist And some of you may have done
15:07 . And I actually have Dennis. you done that in your in your
15:12 , familiar with that concept? Yes . Yes sir. I I used
15:16 to generate a synthetic trace. And tell you to the conventional assessment that
15:21 . There you go. So, experience during this. Now, I
15:26 to sketch this on the board but I would draft a new figure for
15:30 guys. What the heck is this blue box? The funny blue box
15:38 the shape of my swimming pool of house. I used to own in
15:43 . Okay. And there was a set of stairs here where we walk
15:47 the pool and I'm just imagining that going to throw uh maybe I threw
15:55 beer can in my pool. I having a frustrated day after work and
15:59 bear can hit here and starts to waves. Okay. And you know
16:04 if you if you throw a pebble the water, you'll see waves radiating
16:08 from the point that the pebbles thrown the water and some, you
16:12 the wave, the wave field travels the edge of the pool. And
16:16 you start to get, you the reflection, you know,
16:20 so reflective off and there's reflections reflecting the bottom of this. You
16:26 one end of the pool. And, you know, and,
16:35 eventually you get a very complicated pattern waves. Right? And that's the
16:44 field. Okay, So, what drawing here is the way field.
16:56 , in the middle diagram, I'm the way field as well as the
17:00 paths, that would be the path just, that would be the path
17:04 one line of energy associated with the field. So we've got the primary
17:11 in red moving away from the place I threw my beer can. And
17:16 the green line shows the ray path the reflected waves coming back the other
17:21 . And then the bottom diagram. I'm showing is some ray paths.
17:27 . And clearly you can find the where you've got the way that the
17:32 are reflecting. Okay. And so last one, you put some
17:38 Okay. And if I start connecting the points, I can recreate the
17:46 of my pool. The edge of pool marks the boundary between the water
17:52 is mobile and the side of the , which are concrete and the and
17:57 contact between the water and the side the pool. That's the reflector.
18:03 ? And we use exactly the same with wave theory and sizable data.
18:07 waves in the ground that caused the and rocks to vibrate some of the
18:12 . Unlike in my in my pool passes, you know, outside of
18:17 water. That doesn't happen with with with with with with water waves,
18:22 it does with seismic waves, but lot of them reflect off the
18:26 And ultimately in the same way that can recreate the shape of my
18:31 You know, by looking at the paths. We can we can reconstruct
18:35 shape of the underlying strangle surfaces that seismic energy to be reflected off a
18:43 surface that has some velocity contrast. makes sense. And so the series
18:49 diagrams going to, I'm going to next show the ray paths not the
18:53 field. Now, when we conduct seismic survey, just think of it
19:01 doing a an experiment, if you . This is pretty standard, pretty
19:09 for how seismic data is collected Whether it's land seismic or marine
19:15 it's all the same basic process. , typically you've got, I'll draw
19:21 in plan view, you've got a , it's got a string and it's
19:29 a series of streamers and these streamers , do you have phones on
19:37 And the boat shoots impulsive energy into water, it hits the sea
19:43 it goes through the layers and then received by the geophones. And as
19:47 boat moves, it's able to collect of data That cover an area producing
19:52 d. seismic. In the old . One size was one day the
19:56 went in one direction went in another and so you get a get a
20:01 of two D. Lines. These days, most size of data
20:04 three D. The basic concepts of you collected are the same. So
20:09 is the cross sectional view. So we've got the boat, there is
20:14 streamer, Okay, there's the Mhm. And I'll just say there's
20:20 streamer so it shoots a sound wave the ground. It's the sea floor
20:26 bounces back. Of course we're interested ray path from the boat to a
20:33 on the surface or subsurface. And received by a given geo phone.
20:38 that's what these ray paths are. black boxes represent the geophones and
20:44 So those are the only places where receive data, there may be signal
20:49 back here, but there's no receiver listen to it. Right? So
20:54 we don't actually uh We don't actually the entire way field. We only
21:00 the points in between geophones. Now geophones might be spaced 25 m
21:05 Right? And that's pretty close if trying to figure out regional photography.
21:11 the spacing is important. Now in example, I'm just going to show
21:17 uh What it takes to image a point in three D. Space.
21:23 this case it's the black dot. we're trying to we're trying to figure
21:26 where that black dot is in the the surface of the earth. So
21:30 time one we shoot off our source it's an explosion or electrical pulse,
21:37 seismic data using. And you there's a way field that I talked
21:42 and there's one right path that goes the source to the point And then
21:48 received by receiver # two. Then moved the boat or the land
21:56 We shoot another sound wave and then get another a that This is the
22:03 one. It's that same point in earth and that is Read by Geo
22:10 # four in this case. Then moved the array again. And now
22:15 get now we actually get the the red ray path and that comes
22:21 . It's the same point in the As the other two And is received
22:26 Geo Phone six. Okay. And this is an example where we've imaged
22:33 same point in space using three Ray in which the sources further and further
22:41 from the point. So the angle the ray path is getting is getting
22:47 less and less steep. So it be 75 degrees 45 degrees 25
22:53 Okay. And and so this would an example of a threefold dataset.
23:01 collecting the same point in space three , shooting to the point that ever
23:06 more acute angles, sorry, oblique . Okay. That's basically how we
23:14 the data These days. Most data 48 fold Right? So we collect
23:19 same point in space 48 times as move the array and we're imaging the
23:26 point vis a vis increasingly oblique waves oblique ray paths during the survey.
23:35 , what we've got to do is collecting. So this is time one
23:40 to and Time three. We're collecting about the same point in space at
23:46 times. And of course all of is being, all of these data
23:51 being collected? You know in a on the ship board. So then
23:55 we've got to do is we have start gathering the ray traces that image
24:01 same point at different times and gather and put them in the same
24:07 Okay. And these are some of terms you'll, you'll have heard if
24:10 done seismic processing, you've heard of seismic gatherer? You've heard of
24:15 Okay. And you've heard of pre gatherers? So that's what we're doing
24:20 . I'm showing you how the priest gather is collected and then gathered.
24:27 here's an example of our pre stacked . Okay, So there's ray path
24:34 one, which is the most acute of course that hits the the common
24:40 for a cbc Dp sooner travels on vertical axis here until we travel
24:46 So it takes the shortest amount of to go from the source to the
24:50 and then back again ray path to more time because the angle is more
24:55 . So we received the information about point later in time, Offset three
25:02 even later in time And offset four even later in time. So we've
25:07 these traces collected at different times during survey and we gathered, gathered them
25:13 and try to put them in one with me makes sense. Okay.
25:25 . Mm hmm. I'm not sure much you guys know about music.
25:31 , so let's talk music for just little bit. Okay. Does anyone
25:34 who Ludwig Van Beethoven was? And a little bit bad. Let
25:42 . Van Beethoven wrote different kinds of . He wrote string quartets and he
25:49 symphonies. Okay. And have you gone to see a symphony orchestra?
25:56 ever seen a symphony orchestra and know they look like? Yes.
26:01 Yeah. So how do you make loud sound in a symphony orchestra?
26:07 what's the technique for making loud sounds the symphony? Symphony orchestra? What
26:12 Beethoven have to do? What instructions you have to give to make sure
26:18 his symphonies were allowed anyone know playing instruments or playing the same notes at
26:28 same time? Exactly. Right. so you've got to remember it sound
26:33 a frequency. Okay. And so you play, and the trick of
26:39 music is You might have 11th You might have 12th violinists, you'll
26:47 a shallow section. You all you know? So in symphony orchestra
26:53 the first violins all play exactly the note. And as McDonald's has correctly
26:59 if you have 10 violins playing the same. No, it sounds a
27:03 louder. But what's the physics behind ? You've got a frequency,
27:09 What's the physics behind making it What's the basis of weight? Physics
27:16 means when you have 10 violins all the same note? Why are they
27:21 ? What what's what's the wave explanation the sound wave? So I know
27:31 the constructive and destructive nature of Exactly, Exactly. Right. You
27:37 constructive interference. Now the violence are of tune. The frequencies aren't the
27:43 . You get destructive interference. That sound good right now. Have you
27:48 heard of a band called Led Hands up or finger up? If
27:51 have? Yeah. And so what the guitar player of Led Zeppelin due
27:57 make his music loud? He doesn't 10 guitarists, right? He has
28:06 guitar and amplifies it. So he electricity to to greatly increase the energy
28:12 his sound. If you ever got big rock concert, you'll you'll you'll
28:16 they have 20 or 30 speakers each the same sound. One speaker is
28:20 loud enough for stadium 20 speakers makes lot of standard. It's all based
28:24 what McDonald's is correctly identified as constructive . Okay, but what happens if
28:31 add Curves 1, 2, 3 four together here? What would happen
28:37 if we added these curves together these ? What would happen to this to
28:43 ? That that seismic? Uh, know, sizing was basically sound
28:51 they become more destructive rather than Exactly. You'll have peak and trough
28:57 and you will diminish the sound? ? So the whole purpose of seismic
29:02 is to increase the signal? And to decrease the noise and we
29:17 that by gathering information about the same in space collected at different times,
29:22 different angles of ray path. But order to and in order to stack
29:29 so that they constructively interfere, we two artifacts officially, officially pull all
29:35 wavelengths up so they match. And to do that. You have to
29:41 what's called the stacking velocity. It restore the sound to depth. What
29:48 does is it takes out this hyperbolic . Come on. It's an iterative
29:55 . And you know, there's lots geophysicists that work on on this stacking
30:03 as long as you stack correctly. when you add your four traces
30:08 you get a much louder signal, much louder sound. Okay, of
30:13 that increases the signal and decreases the . So that's the essence of
30:22 Of how you collect seismic data and you ah and how you uh Bennett
30:30 it and then stack it to try increase the signal to noise ratio.
30:37 this is a bit of a side Castagna who you may take a classroom
30:42 recognized that the sensitivity of the reflection gas and particularly changes with the angle
30:51 the degree of offset. And so called amplitude vs. Offset or amplitude
30:57 angle. So the priest tax gatherers now being used to directly image the
31:04 . Now interestingly, what we really to know is the distance from the
31:09 to the point. But we can't that data because you can't have the
31:15 right on top of the receiver. you'll blow up the receiver. You
31:18 , it's the source is too That's why you have to have some
31:22 between the receiver and the source. here's a schematic version of the same
31:31 . You know? Here's our There's our receiver, there's a ray
31:35 v. We've got our our two uh to a travel time.
31:42 And that produces this this parabolic or hyperbolic ah pre stack gather.
31:55 and we can we can use some to basically flatten these back.
32:01 so here's an actual example of a tax gatherer. Okay, this straight
32:07 here. This is land data that the signal that goes directly from the
32:13 to that receiver. That receiver that those receiving. So those would be
32:18 love waves and the radio waves were interested in. Those were interested in
32:22 waves that go into the ground and back again. And that's these.
32:26 these parabolic curves. So we need get rid of the first break.
32:31 , there's also some stuff down here are also in this case. This
32:36 be land data. So those would the radio waves, the radio waves
32:40 love waves of the surface waves produced uh seismic data. So here's just
32:55 example of a priest tax gatherer. . And here little bit fuzzy
33:02 You consider C. I. Was . So that's the that's the stacking
33:11 . Okay, sometimes it's very Sometimes it's not so tight. Sometimes
33:16 stack of velocity has a lot of . Sometimes it has two separate
33:21 But any rate you integrate the priest gather with the stack and velocity and
33:27 take these curves and you bring them horizontal. You notice on the on
33:34 Now this is the the priest tax that's had the normal move out velocity
33:41 . So that's that's that's how the that that what we call that the
33:46 migration. Okay. And you can it does a good job of the
33:52 reflections. It's not doing such a job on these deep reflections. So
33:56 still they're still looking like parables The problem is you've got this direct
34:03 in here and of course that produces strange artifact. And then you've got
34:08 area here where you've got artifact and got signal. Right? So somehow
34:14 need to get rid of all this . So you can take the equivalent
34:18 an exact in life and just cut off. Or these days you can
34:22 that digitally preserving some of the underlying reflections. Okay, muting basically means
34:34 rid of all this noise here. rid of that. So here is
34:40 cleaned up pre stacked, gather it's time migrated and it's had the the
34:47 noted out. Okay. And then you do as you collapse all this
34:55 it all together and that gives you single trace on a sergeant blind.
35:04 . So that would be this here single trace on a seismic blind.
35:12 depending on how many uh how many data is Back when I first started
35:20 the industry, 12-fold data was pretty . Then it went to 24 fold
35:24 48 fold and so on and so . But all of a sudden now
35:28 can see there is a salt dome there's some turtle structures and strategic graffiti
35:34 layering. Uh and then the salt is no longer effective. You can
35:39 some nice strata graphic layers. So gone from these weird priest at gatherers
35:46 something that's starting to look more like geological cross section. Okay.
35:54 Now unfortunately I've left off key slide . So I'm going to go to
36:04 white screen for a bit. Now you look at, you know,
36:21 . So this diagram, you I've got a series of of of
36:27 that'd be a negative reflection coefficient, negative positive negative, positive negative and
36:36 on and so forth. And if are sharp contacts, they're going to
36:43 a nice strong reflection. Okay Now seismic data in three D seismic data
36:50 some interesting new tools. Yes you have. Have you heard of
36:57 Okay. Also called continuity court Morford to work at U. Of H
37:13 a big fan of coherence and you , if you have a series reflections
37:22 a series of layers on their offset a normal fault in plan view,
37:29 might see, you know in plan You'll see an area of one color
37:36 is that reflection. And then across normal fault, the color will change
37:41 you've displaced the surface. Right? in coherence data in the raw
37:49 you'll just see say Greg on Dwight coherence looks for any place to get
37:53 sudden shift in the attitude. And it's good for for detecting edges.
37:59 , it's really good for mark and . Now in seismic data, something
38:07 we kind of forget is that every you see a reflection? Alright,
38:13 reflecting a change in the impedance of rocks, Right. And that's because
38:18 the velocity contrast between the layers. , now if you have let's say
38:28 gonna draw a little a little geology , okay, sand celt and then
38:52 . Okay, that's my geological unit . And let's put another unit on
39:00 of it. Okay let's say that unit moves a bit seaward sand self
39:29 then share and then let's do our mythos photography, there's your sandy
39:45 there's your sherry formation. Okay, you need to understand, this is
39:51 critical. Okay, here, you sand on sand contact. So you
39:57 not get much of a reflection coefficient . Here, you've got a sound
40:02 facility, that's going to be a bit faster, little bit slower
40:09 you've got a silt on the little faster, a little slower.
40:15 . Now, despite the fact that no formation contact, there is still
40:18 mud storm and mud stone, you , and maybe the velocity contrast isn't
40:22 high, but it's continuous across that here, you've got a silk on
40:28 contact, but this is a more silt on the most, more distal
40:33 . It might not be, it be too trivial trivial for the
40:37 Ologists to identify a difference. The , If there's a 10% change in
40:43 or even a 3% change in if that contact occurs, if that
40:49 in velocity occurs at a betting contact of the constructive interference of stacking,
40:55 will show up one of the things have to ask. You look at
41:01 formations. Mcdonald's, I don't know you've ever worked in *** Delta,
41:04 the the, is it the body , You know, it's one big
41:09 ft shale, it's filled with So even though it's one formation,
41:14 enough velocity contrasts that that line up these strata, graphic surfaces that the
41:21 velocity changes between Celts between us between , you know, a shady celt
41:28 a silty shale, even though the are almost identical. As long as
41:33 is a small velocity contrast among units would never ever be distinguished little strata
41:40 as long as there was mythology contrast across surfaces. They will be imaged
41:45 seismic data. And so we tend think of coherence as a plan view
41:53 between adjacent traces, but the first coherence is the vertical contrast between beds
41:59 different velocities. And that's fundamentally what data image fundamental. Okay. And
42:08 course, you know, a schism , you know, a zigzag line
42:15 is the geologist attempt to draw a over something that's surely a zone or
42:20 area and areas don't produce reflections, too right? Areas and zones don't
42:28 reflections contact. So all these um, lines that we draw never
42:33 up on seismic dane. So fundamentally seismic image is reflecting off coherent betting
42:43 because of the very nature of stacking I talked about stacking. I talked
42:50 , we get constructive interference, which what Mcdonald's is understood in terms of
42:56 theory. In contrast prophesies boundaries typically destructive interference and so you never image
43:09 . So for that reason, ah fundamentally disagree with Bill Dickinson. Seismic
43:17 are corona photographic and we know that of the actual theory and the way
43:22 we collect the data specifically for the of imaging bedding surfaces. You
43:29 the geophysics that collect seismic data specifically the stack methodology to enhance the ability
43:35 see the surface. And the problem Bill Dickinson is he's, I don't
43:40 , he's dead. I've never never really met the guy. I
43:43 he's never taken the class and seismic of processing. So he just doesn't
43:48 the theory of seismic. He had very immature and very incorrect understanding of
43:55 acquisition. And unfortunately, because he's very famous person, got away with
44:00 complete nonsense and because he was the of the journal, no geophysicist was
44:07 to say, wait a minute, don't know what you're talking about.
44:10 an idiot. Now, the guy's any of the guys are genius.
44:13 an amazing scientist. But one of big mistakes that smart people make is
44:18 think, oh, just because I'm great photographer. It means that I
44:21 everything about everything. I'm sorry. no, he may have been the
44:26 sedimentary photographer in the world, but knew nothing about seismic processing and made
44:32 untrue statements that unfortunately influenced all the . He taught all of the students
44:38 very cynical about sequence photography because he think seismic data was meaningless,
44:44 He thought it was completely mean, the thought that Pete man was an
44:48 , right and dissuaded any of the from believing a word that Exxon said
44:53 seismic photography and negatively impacted a generation students from UCLA Arizona and they're good
45:02 . But those, those students and at those universities. Some of them
45:06 still very cynical about sequence photography. it comes from this complete ignorance and
45:12 hate to say it, but complete of knowledge of seismic processing, which
45:16 why Dickinson simply didn't know what he talking about. So, you
45:19 you always have to be skeptical about even when they're very good because they
45:23 know everything about everything. Okay. that, you know, Pete Bell
45:29 to explain this clearly. Right? here's a cross section from one of
45:34 of pizza. You know when the cross sections, Pete, they'll put
45:37 radio straight this difference between Lithuania photography she's sam's versus seismic reflections. So
45:45 you can see these nice platforms, ? Sure, quite nicely in the
45:50 data. Right? See these dipping . Okay. It's not the best
45:55 of it. But you know, the data that he had in the
45:59 . So just highlight the clan You know, I love platforms.
46:02 , folks. Now, typically geologists well, logs will pick the base
46:08 the formation. So there is the of the upper sandstone, there is
46:13 base of the lower sandstone. so that's the Lysistrata. Graphic base
46:19 Of the two sand stones four and . But it's pretty clear that the
46:25 informs are ignoring and passing obliquely through little strata. Graphic pick,
46:33 So the seismic data don't care whether picks the base of the sandstone.
46:38 seismic data don't see the base of sandstone, right? They're ignoring
46:44 Why? Because there's no contact there speaking, it should be a zigzag
46:51 milan. Okay. And now we that the seismic reflections obliquely passed through
46:58 base of the sand stones which are drawing with a zigzag line, which
47:03 an inter fingering relationship. Not this contact. And trust me, how
47:09 of you have ever been asked to bases and tops? Have you ever
47:14 asked to pick bases and tops? , if you're a professional geologist,
47:19 of you will be asked to do . Thank you. So,
47:31 seismic data images straight or surfaces. of course the surfaces by definition are
47:37 strata graphic contacts and by definition they corona strata graphic significance and you get
47:42 of reflections that change their orientation and termination of reflections and fundamentally those defined
47:49 sequences. So, if I was to stand on one leg and define
47:55 , geography with one word, I say fundamentally. Sequence photography is lap
48:02 . It's the observation of changes in strait of geometry and configurations. That's
48:08 all that. But that's a big of it. Let's just give some
48:13 here. We see some flatlining Okay, that is pretty clear that
48:20 truncated and that truncated by this undulating here. So that surfaces truncating the
48:36 reflections which we interpret as as shelf stones and then lying above this irrational
48:45 , we see these nice curving reflections little hard to see what's going on
49:01 . Some coming back the other way these are point bars in the
49:32 So you've got a marine shelf, stones and you've got nice lateral accretion
49:37 representing migrating river channels, filling an valley. All deduced on the basis
49:45 the seismic reflection data that our imaging geological units. Now this is this
49:51 actually pretty high resolution seismic data. notice the vertical scale here is in
49:58 . The rule of thumb is that milliseconds of two way travel time Is
50:04 one m of strategic graffiti. So second, which is 1000 milliseconds is
50:11 one kilometer. Okay, so you're at about Again, it's about 75
50:17 to the sea floor. And we've maybe 100 and 10 milliseconds here.
50:22 you're looking at about 100. About 200 m of strategic graffiti in this
50:27 section. Okay, we can look rocks. This is the fare and
50:33 in Utah. And here we have nice incised valley filled with lateral recruiting
50:39 bars that are eroding into these marine deposits that show nice of precaution in
50:46 . There's three of them here. . And so we can see a
50:50 cross section with the various environments of recording by the actual beds and then
50:56 can see a seismic example of the thing. So we can go from
50:59 geophysics and then we can find a and logs of the geology. Here's
51:06 example of Utah of a nice programming . Okay. We see these nice
51:12 surfaces here. You know, I platforms. Right? And it's kind
51:17 down lapping onto this money unit Right. That's kind of the down
51:22 surface here. Okay. And this be a nice delta deposit overlying a
51:29 delta. Okay. And we see up at the top of the sand
51:37 , there's a flooding surface there and see down lap at the base of
51:40 sound. Here's an example of geophysical of a nice there's the Klan informing
51:50 there's the sand's going into shales. sand's going into shales. You can
51:55 sort of see the shoes online Okay. And you can see these
52:01 different reflections In this geophysical data. is ground penetrating radar data, which
52:08 of investigation is 10 m. But still geophysical data, it's a wave
52:13 with the layers bouncing off the geological . What we see is that the
52:20 reflection bounces off the the geological surfaces contacts. And the physics is similar
52:27 or not it's ground penetrating radar data whether it's seismic data. The principles
52:33 basically the same and this gets us what's going to turn into the second
52:41 . So we have various kinds of of surfaces with each other base
52:50 It's a general term used when you an upper surface terminating against a lower
52:57 . If you have an upper Uh huh determining against a lower surface
53:03 the distal direction. We call that lap. If you have a flat
53:10 on lapping a more proximal surface, call that on lap. Okay?
53:16 if you have a dipping surface terminate an upper soap as we call that
53:21 lap. Okay? And if the lap is associated with erosion, then
53:26 call that truncation all top lap all top lap. So top lap
53:38 the this is the disappearance of a against upper boundary. Base. Lab
53:44 a discipline to surface against the lower if it's approximates on lap. If
53:49 just till it's down lap. Top is usually from digital to proximo.
53:54 it's if it's irrational then we call truncation. Top lap. It can
53:59 difficult to distinguish, but sometimes called all top lap from truncation of top
54:05 . Of course if we have no lap out then we have what's called
54:10 concordance or a conformity. Now if have top lap plus down lap,
54:20 we have units one, two, and 4. The unit is getting
54:27 . And to see what direction and can refer to that as offline.
54:34 , sometimes units can pro grade in way and sometimes they can pro grade
54:42 way. These are not all These ones are because these are actually
54:49 our diagram. These would be on even though the unit's programing seaward.
54:56 so we have these different times of out down, lap on, lap
55:02 lap concordance anger around conformers with down above and truncation. All top lap
55:12 . And we can use the geometry the lap out to infer something about
55:17 direction of sediments are moving in this , the sediments are migrating landward.
55:22 some element of maybe transgression going on . We've got the migration of
55:27 C words to some element of regression on. No and so on and
55:33 forth. Okay, How about we a little five minute break.
55:44 And we'll come back and I'm gonna you some questions about this uh cross
55:50 as we move forward. Okay, take a little, It's 555 and
55:54 take a 10 minute break. come back in 10 minutes. Okey
56:11 . So um mm hmm. Angela . Not what I wanted to
56:28 What is that kind of lap out lap. No, it's an upper
56:47 terminate against the lower surface. That's small. That's distal McManus. You
57:00 to have a try. Don't That's down lap. Okay,
57:08 What do you think that is the surface lapping out against an older dipping
57:16 . Is it on left? Very . Angela here. You see the
57:25 surface turning against the lower surface. that download? Very good. What's
57:44 online? Very good. Um McDonough this what is this relationship?
58:02 good. Okay. You guys are business. Okay. Um What about
58:20 Megan? What would that be? ? Upper surface again? Is it
58:30 down lift? No, it's a surface terminated against an upper surface.
58:37 it's on lap. No, that be an upper surface turning against the
58:41 surface. Yeah, Angela. You what that is? Same here.
59:07 lap. There we go. Top . Okay, so I think you
59:12 the basic gist, I hope. . So there's they don't have a
59:23 of lap out marked on this That was your down laps. These
59:29 on laughing. That would be a lap surface. That would be on
59:39 . Um These are all on This is the basis of seismic
59:46 Okay. Uh And here you can there's a cloud form and then see
59:53 it shifts down, right? So could also circle the rollover. It's
60:00 . That's degradation along. And that's Nation Als improvisational. And then that's
60:08 to rise up a little bit. . That would be presentational aggregation.
60:13 . That's the essence of what we're to be doing in the next assignment
60:18 interpreting these lap outs in a synthetic . We'll get to that by the
60:25 of the day. Can you just me or the difference between the on
60:30 and the top flap. Yeah. . So if we have or profile
60:49 the unit that's doing this approximately, means landward. This don't mean
61:01 Okay, on lap is where you an upper surface terminating against the lower
61:12 in a land with approximate direction Lap is where you have an upper
61:19 turning against the lower surface in the direction. Usually on lap would be
61:24 relatively horizontal surface, determining against a surface. And down lap would be
61:30 dipping surface terminating against a relatively horizontal . That makes sense. Ted
61:40 Okay, so, uh yeah, sure a few other examples.
61:52 the general configuration of seismic data can used in the example here, for
62:02 , or in the example here, know, we had this kind of
62:07 geometry. Okay, that's a very seismic geometry. And then I
62:13 looks like river bars. Then we very flatline reflections that has flatlined muddy
62:20 straight up. So the configuration the of reflections can be used to determine
62:27 the seismic faces, which can be directly to a deposition environment. In
62:33 same way that when we saw dipping , you know, those represent those
62:38 front platforms. Okay, and here saw flatline reflections. That would be
62:46 shelf deposits. And then we see seaward dipping platforms that represents the
62:52 So we cannot identify a shelf in slope environment. Okay, this diagram
62:57 , you had some mounded faces. , so these little mound of things
63:05 and those are interpreted as carbonate reef . Right. So the idea is
63:09 shape of the reflections can be used directly interpret the deposition all system.
63:15 I talked about de positional systems. , sometimes you get them. This
63:20 not very comprehensive and they have got weird things in here. But you
63:24 , chaotic seismic reflections can indicate You can get these waves. Obviously
63:32 already talked a lot about the fact on a lot of seismic data,
63:35 see these Sig model climate forms. , good examples. There now represents
63:41 migrating shelf slope complex, Right? grading shelf slope complex. And so
63:46 an example of a seismic line. , it's not the best data from
63:54 offshore Morocco from the mitch model The various letters here represent the
64:03 Okay. Ah anyone know what R. Stands for? Read
64:18 What's what's T. R. Stand ? Is it for the age of
64:26 rocks? And what's tr is the for traffic and jay, Jurassic.
64:34 . Efficacious. Right. T. and T. P M.
64:54 What's P and A. You should your time scale. Mm hmm.
65:12 , no, no. P E . Oh and P pee pee.
65:24 what Dennis do you know? I hear you? I'm going through my
65:48 scale. Okay. At the palace here, seen a legacy. Mean
65:55 pleistocene. Sorry, apply a scene placed a scene. Those are the
66:02 of the centers. Okay. And are divided into the police surgeon and
66:09 Gene, which are this is an slides and that those Anyway. And
66:14 the K. one is seeking to one. It's broken in subsequent
66:21 You got the J. One the J. Two sequence of
66:24 C. Three sequence. And they've up into 2.12 point two. So
66:28 is showing the basic sequences. And what is that lap out
66:38 Madonna? What's that? And what's ? And this here is the dark
66:55 , nope. It's an upper surface against a lower surface. This is
67:04 landward margin, approximate margin. That's seaward margin. So that's the down
67:11 there. You correctly identified that? this? The top lap?
67:22 it's a lower surface terminated. The surface turned against the lower surface.
67:31 , here's what looks like. what is that relationship is proximal?
67:50 it's on lap on lap exactly. , okay. On lap correct.
67:59 , you'll have lots of chance to this in the next exercise. And
68:02 the lap out relationship. We used define the sequences. Okay, and
68:07 here's the faces. The faces are simple. You got a flatline shelf
68:12 you got a slope. You've got basic faces. Right? There's maybe
68:19 uh faulting going on here. That's these uh shelf beds. And there
68:26 a sham line that separates the shelf the slope. Right? So the
68:32 data, we can pretty easily distinguish slope and the shelf facings.
68:38 I don't know whether this is a shell for a plastic shelf, but
68:42 the shape of the of the of the shape of the reflections can be
68:49 to interpret the deposition environment. Now this diagram here, his his
68:56 section eight a prime. Okay, is this um wedge of sediment
69:04 It's on laps landward, It down seaward. It's got this U.
69:10 and there is a down lap There's the on lap limit there it
69:14 on lap the black arrow down lap the white arrows down lap distantly on
69:19 approximately on lapping at old shelf engine . Okay. And and we can
69:28 the limits of that unit. There's limits of that unit. Okay,
69:35 that's a plan view map of this there, that little thin wedge of
69:41 . They could also measure the two travel time and make an icicle format
69:46 would be the two way travel time of it. And if you know
69:50 it's death migrated then you can convert to a thickness. Okay, in
69:56 old days we would have this is D. Data, we would mark
70:00 lap outs on the one the lines on the two D. Lines.
70:03 then use that to map the extent the sedimentary wedges that we were interested
70:11 . So here's more size McDonough and know what is this relationship here?
70:20 books that indiana. It's the correct? That's down up,
70:31 What about this here? Another Kelowna here. What's that relationship right
70:47 Is it the top lab? Angela. You wanna tell me what
70:53 is? Mm hmm. Sorry that my guest. To was top flap
71:01 lap would be a lower surface terminating an upper surface. This is an
71:07 surface termine against a lower surface. on left, exactly, right on
71:12 . Right. Okay. And so lap out are used to map the
71:16 seismic sequences. Okay. But here a close review. Okay. And
71:21 you can see the lap out a more carefully. What's this? So
71:28 the surface. The upper surface is against the lower surface. What would
71:32 be there? We're here, Hello again, all downloads correct.
71:52 about here platform here and you've got these smaller platforms, Upperclassmen forms terminating
72:03 that lower surface. What would that or not correct? Right. So
72:09 getting the idea of these online relationships of course ultimately the latter part relationships
72:14 used to interpret the sequences and the tracks and of course you can look
72:20 the so what is this here? that again? I'll ask you again
72:35 . So here's an upper surface turned a lower surface. So no that's
72:46 on lap the upper surface. turning the lower surface again, This is
72:53 and that's the C. Word. . So you should have had to
72:57 this idea of proximal and distal. . That's a very very basic concept
73:02 geology. You may not have as experience that with that because of your
73:07 background. You need to sort of out which way is the land and
73:10 way. See otherwise you're gonna struggle with with lap out relationships. So
73:16 you. Want to tell her what is, download app and what's
73:30 Top LAPD, nope. That's an surface against a lower surface online.
73:39 then what's this a lower surface against top surface? Talk, laugh.
73:46 , laugh. Okay, how about ? What's this online? And
74:01 download app. And here top There you go. What about
74:16 What's that right there. Top No. Look at it carefully.
74:29 , what you're saying? Let me this a bit bit more carefully for
74:33 . You've got this chloroform here, you've got a lower chloroform, then
74:40 one. And then another one. what is that relationship right there,
74:56 . Do you know what it It's on lap exactly. Right,
75:03 . This is top lap right, lap is this on lap is
75:14 See the difference? Yeah, you're there then of course, you can
75:22 that to interpret the the aggregation of of degradation of recommendation that we talked
75:30 . Now look at this example Okay, um what's the accommodation
75:39 So I've got the shoes on drawn the shell from the slope here.
75:42 about to the right of the cross ? Where is the shelf slope boundary
75:47 ? See it's flat and then it's . See that. So the shots
75:54 is actually almost vertical from dipping too . So that basically has a strongly
76:03 , allele per organizational and then maybe degradation. Als accommodation succession. That
76:10 sense. A. P. So in the early days we had
76:17 slug diagrams. Okay, and you there you've got the the online relationships
76:28 . You got on lap here. , what happens is between this sequence
76:35 , Let's call that sequence one and to you've got to shift. And
76:40 the on lap is in this approximate position in this lower sequence here and
76:47 it shifts to a much more seaweed and that marks the sequence boundary that
76:54 a massive basin would shift in on . And you'll hear that term a
76:58 a basin would shift in on lap have to be able to recognize on
77:03 to know whether or not it's shifting in winter landward. So now we're
77:07 at at the shifts in position. , so again, this is all
77:12 lap all on lap, you've got bit of truncation or top lap of
77:17 lower units against the upper surface. here it's a little unclear what they're
77:24 to here. This is where it a bit a bit difficult. That
77:28 be on lap or it could be depending on whether you think that surfaces
77:33 truncated by the upper one, whether on lap in the lower one,
77:36 it's not always obvious picking truncation versus lap. Sorry, sometimes in an
77:44 like that, it can be hard figure out whether these are on mapping
77:48 . So vacation with chips is on or if their top lapping against upper
77:54 , these scenarios can be difficult to sometimes. So here's our slug.
78:00 this is a slug diagram with nothing lines drawn. That's gonna be your
78:04 exercise. But here's the same slug . But now we've got some sands
78:13 and some deposition environments. BF is basin floor fan, SF is your
78:20 fan. This is your low stand , maximum flooding surface and so on
78:27 so forth. And we'll talk about in more detail in the next
78:30 Okay. And there's also a slug for carbonate systems, which I won't
78:36 into a lot of detail. Now mentioned, I already mentioned the fact
78:42 when you're collecting three D seismic Okay, the boat moves in one
78:47 , then it turns out it goes the opposite direction, back and forth
78:52 we refer to align in threesomes seismic that's in the same direction the boat
78:59 as an in line, a line collected perpendicular to the direction of boat
79:05 is called cross line. Okay. sometimes you can get, you
79:11 it's not easy folks driving a boat the sea, turning around and driving
79:16 in exactly the opposite direction 25 m from where it just drove.
79:23 This requires extremely sophisticated GIS systems, positioning surveys and and and correcting navigation
79:32 . And there are entire groups of who do nothing but work on cleaning
79:37 navigation areas and seismic data. The of 3D seismic standards that you can
79:42 and dice it vertically horizontally. Something have to talk about in seismic is
79:49 idea of the resolution. Okay, here we have a very traditional problem
79:54 seismic data. You just have a . Okay, so the unit that's
80:00 that's pinching out. Okay. And the and you've got a negative reflection
80:08 along the top of the unit and positive reflection coefficient on the base of
80:12 unit. Okay, so there's a from the top and there's a pulse
80:19 the bottom, like we explained. what happens is the unit gets
80:24 You start off by getting constructive interference to a maximum about this point.
80:31 , And then you start to get interference. And so that you'll notice
80:36 that that the wedge is getting harder harder to resolve as the unit gets
80:42 and thinner and thinner. Okay. about one when the thickness of the
80:49 and the thickness of the units equals quarter of the wavelength we call that
80:59 tuning thickness. Okay, that's the thickness. And you get constructive tuning
81:07 it's thicker and destructive tuning when it thinner. And Mcguinness has already advised
81:12 about this idea of constructive versus destructive . Now, if you want to
81:18 out the thickness of the bed, best way is to image the top
81:21 base. But when unit gets get when units become thinner than the wavelength
81:27 the data, you can use the in amplitude at about a quarter wavelength
81:34 infer the thickness of thin units that can't resolve the top and base.
81:40 you can guess because of the increasing that the units about a quarter of
81:45 of the wavelength of the of the wave length. And that will vary
81:50 on whether it's 10 2030 40 50 60 hertz hertz data. And it
81:55 of course. Mhm. So here's little table that I'll ask you to
82:06 of keep an eye on. I'll asked questions about this. So,
82:10 know, water has a velocity of 1500 m/s shallow, Lightly cemented rocks
82:18 2000. You get down five km . You know, two pennies or
82:23 . Well cemented, they get Maybe 5000 m/s. Conventional seismic data
82:30 typically have a range of frequencies within . So that that Rika wavelet will
82:34 anything from 20 to 50 or 60 data. Uh huh. The frequency
82:40 with debt. So you typically only high frequency stuff shallow. So what
82:45 means is that you know the 50 frequencies in relatively slow rock. Well
82:52 can can can detect something that's about m thick. It's about the tuning
82:58 of relatively high frequency spec data. trying to image image the thickness of
83:03 that's five km below the surface. in very very fast rock With low
83:09 low frequency data it's got to be to 62 m before you'll even be
83:14 to detect it. Okay so this of gives you an idea of the
83:18 the ability to detect units of a thickness. Okay. And it's it's
83:24 function of Of the depth of burial rock, the velocity of Iraq.
83:29 the frequency of the seismic data. you can resolve units of 10 m
83:35 which is relatively thin in shallow McDonough and the and the and the
83:39 gets worse and worse as you go . Same thing with three D.
83:47 . The final zone refers to the of the seismic wave and so depending
83:53 whether you're 123 or four Four seconds in the data. So four seconds
83:57 be about four km deep depending on velocity of the rock. 2003,000 4000
84:05 5000 m/s. That should really be per second. And the frequency which
84:12 course decrease increases with decreasing with The largest thing that you can resolve
84:19 relatively shallow. Seismic data might be that's 140 meters in radius. And
84:25 you get down deep seismic data, hard to image something unless it's bigger
84:29 a kilometer. What does that Let's say that you're trying to image
84:32 ancient river channel like an ancient meander . Okay, if the meander belt
84:38 smaller than a kilometer in diameter, . And you're down in very
84:44 dead and you're never going to see . Whereas you'll see it easily if
84:48 in shallow. Uh if it's if shallow in the size of McDonagh,
84:53 give you some examples. So here's cross section of seismic data. And
85:00 you can see that there's a black , then it turns to white trough
85:05 into a black peak. Now, I would look at that inversion of
85:09 aptitude. So it's it's just But when you slice the data through
85:16 point se 75 seconds, you see beautiful linear. Sorry, this beautiful
85:23 channel film. So you're actually imaging channel in the seismic data. This
85:29 a real revolution in looking at three . Seismic data, you can actually
85:34 the de positional systems in three Data in plan view. This is
85:39 for targeting sand field units like a filled channel. For example, Here's
85:46 example of three d. seismic data the left and this is an old
85:51 image of the modern Oaxaca delta on right. You can see that this
85:55 a marine data because you can see striping right, the boat was moving
86:00 that direction. What you can see these beautiful bars right with little tidal
86:11 coming into it. And this is if we look at the that,
86:18 this is cal Montana Borneo and you've the shelf edge, you've got shelf
86:24 deltas. Then you've got the modern delta up here. And so the
86:29 edge deltas look like they're more river and wave dominated than the modern type
86:35 Oaxaca. This is 100 milliseconds below sediment water interface. And this is
86:40 seismic image. This is not a and yet it looks like a plan
86:44 photograph of a delta. This, is what we call seismic geo
86:50 One of the first project I ever . The size of your apology was
86:53 Henry post mentor. So this feature a channel belt of the Mississippi.
87:00 channel belt shows us the black and . There's a fairly wide channel about
87:05 and two thinner ones here. Here's map that shows my interpretation of the
87:11 and then on the bottom of the line. So again here we see
87:15 white trough, then it turns into black peak up to there and then
87:21 to it. So we see an of the attitude and the inversion of
87:26 the fact that you've got a channel into a muddy flood plain. The
87:30 is most of these channels of So there Freddy slow and the surrounding
87:35 are a bit faster and you can the edges of the channel belt quite
87:40 on the seismic data and that's the of sand made by the channel as
87:44 migrates around. Okay, excuse I have a question. And these
87:50 they contain although basically fueled descent premier sand and they're filled with gas.
88:01 then here we have these little side and you can see actually there's a
88:06 there's the channel right there. what's interesting, we see a velocity
88:10 down below it and that's because this a gas charge sound so that the
88:15 slows down in the channel and of it's pulled down because of the velocity
88:20 . And because it's a gas filled compact very well, we see differential
88:25 on the top of the sandstone. here we can see the channel image
88:29 nicely in cross section of course when go looking at two d. seismic
88:34 all of a sudden I look at and I can see all these bright
88:37 and those could be channels. Historically, I would say, well
88:41 just noise right there, that there's channel there. Right, So you
88:46 good at sort of looking for a where you've got inversions of the amplitude
88:50 you know, 20 years ago we all that's just noise. Now with
88:55 treaty seismic data, we can oh no, those are actually
89:00 Okay. Now the last thing I to do is talk about sort of
89:07 final, final theme. And of it's another thing that sort of really
89:15 missing. And and the understanding of photography was done excellent. I went
89:23 work at Exxon in 1981 and they dead clear when I went to work
89:28 them. They said, we're big of plate tectonics. It helps us
89:32 the structuring the structural history of based the formation of traps. Uh,
89:39 but you know, let's say that got a nice anti climb and seismic
89:43 . You know, the problem, were drilling these structures and they were
89:46 with shale. They said, we're doing a very, very good job
89:50 predicting the mythology of these traps, said, and that's because mythology is
89:55 dependent on the traffic configuration, you , rises and falls of sea level
90:01 . Whether you've got sound out in middle of basin or shale out in
90:04 middle of basis. But of course times of high sea levels, you
90:08 source rocks at times of solar low levels. You could put reservoir sands
90:14 those source rocks. So they realized that if they could understand C double
90:19 through history, that would give them better way to predict source rocks and
90:25 placed on top of the plate tectonic , which helped them understand the structural
90:31 and history of the basis. They , if we put the two
90:34 we'll have a vastly improved exploration Now they didn't feel it was necessary
90:41 tell anybody else their approach. And they didn't need to remind the world
90:47 they understood plate tectonics when they published their their sequence photography and they mostly
90:53 on what on what they felt was about their their sequence photography which was
90:58 sea level through time. Unfortunately the on the west coast and east
91:05 I criticized mistakenly believed that Exxon somehow believe in plate tectonics. This was
91:11 true. They just didn't advertise the . In fact they were happier if
91:17 thought the world believed they were idiots then they would be left alone to
91:21 their business and have the competitive And they frankly couldn't care what academics
91:26 thought of them. And if if thought that they were idiots then they
91:31 teach students their technology and that will left as a proprietary technology that you
91:37 only learn at Exxon. Okay, Exxon are quite aggressive and not explaining
91:45 they that they were extremely confident about plate tectonics but they deliberately decided to
91:51 that quiet when they act when they teaching their sequence photography for for business
91:58 . Now, you know what's interesting the history of seismic photography is
92:04 you know, there's only a few that had a global database that could
92:09 compared seismic data, particularly on both of the atlantic ocean. Where Exxon
92:15 lots of data as well as information the arctic and a little bit of
92:21 in the pacific associated with the indian associated with their Australian assets. I
92:28 love this. This, this I just took the national geographic map
92:32 the world and put it and put dots from the, from the,
92:37 is a 1977 diagram from Exxon And just illustrates how fundamentally the world has
92:44 since 1977. Almost no expiration was in africa. Communist china and Russia
92:51 completely off limits. No westerners were to explore their, almost nobody was
92:57 any exploration for oil and gas in . Reliant energy obviously have changed all
93:03 . Uh, and there was absolutely expiration in Southeast Asia because there was
93:07 Vietnam war going on there. So did Exxon have data? Prudhoe
93:12 Alaska Calgary, Denver Houston, new Chicago, which is where Amoco,
93:22 is one of the seven sisters used have their business. Um uh then
93:28 had some interest on the East but there's been a, an exploration
93:33 on the East coast. And of they had interests in Newfoundland that was
93:37 back to their calvary office. When took my very first job in
93:42 my first project was looking at a gas on gas prospects up here
93:46 the North Orphan basin following the discovery Hibernia in the late seventies, they
93:53 also had interest in the North They have had an office in
93:58 Um they obviously, you know, used to have business in Saudi Arabia
94:03 that it's still, still links in seventies to Saudi Aramco a little bit
94:08 interest in Morocco. Everyone liked to in in europe, in the paris
94:13 . And of course a little bit data from the, from the irish
94:18 and they had offices in Aberdeen and had offices in London. And of
94:23 this is one of my favorite there were oil and gas interests off
94:27 coast of the Falkland islands, known the Argentina's mar venus. And as
94:34 know, the Argentinians invaded the Falklands try to steal it from Britain
94:40 Thatcher sent the U. S. british army to oust the Argentinians from
94:48 and retains their business interests in the Islands. There's a huge continental shelf
94:53 South America, all of which is for oil and gas. And of
94:58 in the UK hoped that if anyone was discovered there, they would own
95:03 right. And of course the other where Exxon or esso had business was
95:10 was esso Australia. And of course is the massive Gorgon gas field that
95:16 one of the largest civil engineering projects where Exxon and BP and Chevron have
95:22 interests. There's been an exploration moratorium the entire east coast of North
95:29 Pemex was closed for business for many . And of course now Venezuela's had
95:34 up Columbia Brazil. So, you , a lot of the world has
95:38 up since 1977. And anyway, digress. I do love that geopolitics
95:47 of course what these, what they was seismic data from offshore basins around
95:51 world. And there is our beloved form, right? There's a high
95:56 delta at low stand, the delta the shelf edge and starts pummeling sediment
96:01 submarine fans. And so this is kind of data that Exxon had get
96:07 the 70s. What they observed that were these blue units right, that
96:12 actually off the seismic lines on And they had these green units that
96:18 to be confined strata graphically see what the shelf slope break. So they
96:24 these these wedges of sediments that were completely see with the shelf shelf shelf
96:30 break and show this on lapping geometry with the red arrows and then they
96:37 these blue units that were much more and had a down lap in relationships
96:42 they broke those into blue high stands green low stands. That's good.
96:50 need wheeler diagrams of the on lap . So that's the coastal on lap
96:56 and the blue units represent times in the shelf is flooded and the green
97:01 represent times when the shelf was exposed sedimentation was confined seaward of the shelf
97:07 break. These are the kinds of that they had. So we've been
97:14 at and, you know, seismic section. So that's the actual
97:24 Okay, This would be a a drawing of a folded unit with an
97:32 nonconformity over land by colony forming unit then over land by some on lapping
97:38 faces. Okay, so we've got of units 10 to unit four at
97:52 below that sequence boundary. A. got this nice planet forming unit going
98:00 units 11 to 19 And then that's lap by units 20 to 25.
98:07 we render that wheeler space below, noticed that right here, We've got
98:13 11 overlying unit 10. So that's con formal part of the cross section
98:20 you go to the left, You've units nine 25 eroded away. So
98:27 used to be sediments in here, been eroded away. That's the erosion
98:30 hiatus or what will refer to as erosion of vacuity. Then after unit
98:39 And before unit 11, you've got period of non deposition here. So
98:43 is never deposited here. So here the young the oldest unit above The
98:50 sequence is unit # 12. And here it's unit # 13. So
98:55 hiatus is increasing in direction towards the approximate part of the cross section.
99:01 then C. Word you've got down if unit 12, 13,
99:06 15, 16 and so on. that creates a non deposition. All
99:10 it. Then you've got an on on conformity here. It's 2021 22
99:16 lapping unit 19. And that creates non de positional hiatus at that surface
99:22 . Because here you've got flatline beds and flatline beds below that sequence be
99:28 technically is called a para conformity. there's no angular discordance or irrational
99:45 So the next thing Exxon did was these these wheeler diagrams of the So
99:53 the previous page at this page. were they able to correlate all
99:59 I understand you didn't do love original or is zero mentality What our disk
100:06 done? Like how do they make limit of control? But how what
100:11 of doctor was there do they use ? It's all based on this kind
100:16 data. Okay statistic. It's all on seismic data. They might have
100:22 wells with bios photography as I explained , fundamentally all this. All this
100:29 from Exxon was based on seismic So this is basically just imagine this
100:34 a seismic line. I've taken the data and I'm just showing the
100:39 Okay, that makes sense. And know, they've got some age control
100:45 . So you know, 25 million of time. Ah Yeah. And
100:51 here then is some some real So this is the the Triassic Jurassic
100:57 from the North Sea. And in the in the middle column here we've
101:03 the corona strata graphic chart. So are the times photographic diagrams schematically rendered
101:12 the seismic lines. Then they convert to their relative coasting on lap
101:19 Okay. And that's how they define various sequences. Right. And so
101:28 are the sequences that we saw The K one, K.
101:32 the J. Three J. To Triassic. That's basically what we saw
101:41 this diagram here. Right. So many uh Dennis, their current in
101:47 in the base of lap out And well, data that can vibrate
101:51 age of the seismic sequences. That sense. And there's the tr the
101:56 one J. 2. And these basically the sort of schematic wheeler diagrams
102:04 those sequences. Here's data from West . That shows the various sequences.
102:12 is an interpretation of this seismic The texas gulf coast, boy.
102:17 boy. Do they ever look And so what they, what they
102:22 was this incredible similarity of on lap . Thanks. They were able to
102:30 those in wheeler space with time on vertical axis tied to the the ages
102:35 the rocks stages and that ultimately led develop this global chart of global on
102:42 cycles. Okay, so this is global chart that they invented or they
102:50 put together really was a pretty amazing of work, even though it was
102:54 , heavily criticized. So in 1977 published this, this history of global
103:01 level through geological time. Okay. these would be the first order
103:09 So basically this is the breakup of going into the sock sequence with a
103:15 of very high sea level. Then have the assembly of Pangea that peaked
103:20 the Triassic Pangea broke up and of the cretaceous was a time of again
103:26 high sea levels reflecting a lot of oceanic crust. So these first order
103:33 Are basically correlate with the Wilson cycles 20 Wilson, the famous Canadian geophysicist
103:39 identified that over the last billion a years, you've had the growth and
103:45 of the super continents. It's cycles last for about 250 to half a
103:51 years and 50 million to half a years. Then they noticed that there
103:57 these second motorcycles. By and these correlates the slaw cycles and those
104:03 major mountain building origin ICC events. . And then if we look at
104:11 younger part of this curve, we to see the higher frequency sequences.
104:17 these are the third order sequences and are the ones they thought were you
104:21 in origin? We can argue about drives the use static curves. What's
104:28 is when they published these in they blacked out the cretaceous part of
104:32 curves that was proprietary. That we're that to explore for reservoir seal pairs
104:38 cretaceous and they didn't want to reveal secrets. What's interesting is when I
104:45 at Memorial University of Newfoundland, I 21 years old, I took a
104:51 called the strata graphic History of North with Noel James and bob stevens and
104:58 learned about the slaw sequences these And they also told us that there
105:04 this new publication from a PG that went beyond the sloth sequences and showed
105:11 there was this history of global sea . I remember them telling me,
105:16 know, tectonics was was was was big thing in the 70s.
105:20 we got a feeling that this this statics uh size of photography is gonna
105:26 the next big thing in geology and turned out to be right. What
105:31 so interesting is, you know, saw these curves as an undergraduate blacked
105:37 And boy, you want to get 21 year olds interest, show them
105:42 that's proprietary. Right? Show them graph and blackout part of it.
105:48 I went and left Calgary and got job with S. O. Calgary
105:53 the first thing they did was give the the cretaceous sea level curves,
105:58 blacked out because I was exploring for rocks in orphan Basin. I was
106:02 , wow, I get to see stuff that nobody in the world can
106:06 . It really was inspiring, I tell you. And that got me
106:10 on seismic photography and sequence. And course, eventually by 2008, Bill
106:17 left Exxon and continued working on the level curve and put together a sea
106:22 curve for this is the this is paleozoic. So from Cambrian to
106:30 we've got bio zones here, the stages, the geological timescale. You've
106:38 some dates, then you've got the lap curve. So that's basically the
106:42 diagrams, but eventually they converted that the actual sea level changes and I'll
106:49 about how they do that do that a bit and then uh ah
107:01 at oh man, I'm just bad I'm not doing good on names today
107:07 or say glenn miller, but he's trombonist ken miller, ken miller at
107:11 University uh you know, did a of work on the New Jersey self
107:16 put together a revised cretaceous to cenizo . You notice gets really busy when
107:23 get into the modern glacial periods. , so of course what drives these
107:28 frequency glaciation ins we know now that called, They're caused by glacial you
107:35 . This is the dello 18 a . So this is a measure of
107:40 oxygen 18 isotopes of deepwater foraminifera, geochemical systematics behind this is pretty
107:50 When water evaporates in the ocean, preferentially evaporates the lighter oxygen 18.
107:59 , Preferentially the water that goes in atmosphere is enriched in oxygen 16,
108:04 is the lighter isotope of oxygen That back to the earth forming ice during
108:09 periods. And so the ice sheets rich in oxygen 16. And the
108:13 seawater is richer in oxygen 18. , so during glacial periods which are
108:21 of very low sea level, uh the the foraminifera have higher oxygen 18
108:29 their shells because the oceans are rich oxygen 18 when the glaciers melt and
108:35 never goes back to normal, All oxygen to 16 goes back into the
108:40 and that's reflected in lower oxygen 18 16 ratios in the in the in
108:48 in the calcite and Aragon night, the forearms make their skeletons from very
108:53 story. So basically the percentage of 18. The shells of deepwater foraminifera
108:59 extremely sensitive to the average temperature of oceans and that reflects the average temperature
109:04 the earth and that correlates to glacial . And so we see these beautiful
109:09 glacial cycles with glacial builds up to to the maximum glaciation ins rapid
109:16 Another glaciation melting, advancing glaciers, melting, advancing glaciers and rapid melting
109:25 the record of foraminifera. Lol, you chemistry? That's a good proxy
109:31 seawater temperatures and therefore see double change goes back now to easily a million
109:37 . Okay. And of course global is caused by global sea level change
109:45 caused by changes in the volumes of oceans. And that's driven by plate
109:51 . As the oceans grow and the oceans are light because they're less
109:56 they displace water and the continents and causes sea level changes that are very
110:02 . That operates over tens to hundreds millions of years. Okay. And
110:06 includes the first and the and the and 2nd order paleozoic and cretaceous highs
110:15 sea level that reflect those Wilson The faster sea level changes caused by
110:23 ins in order to drop sea level the glacial period. You've got to
110:27 the water out of the oceans. continents. This only works of continents
110:32 are in higher equatorial or higher You know, if you're at the
110:37 , it doesn't work so well. , you know, as long as
110:40 got an antarctic continent, you can a lot of ice there. And
110:44 course because you've got north America and of europe and Russia in the Northern
110:51 . They can also store ice. one of those ice sheets build up
110:54 lower sea level and doesn't help to the oceans. You've got to get
111:00 ice on land. Okay. And need changes in Earth's temperature. The
111:07 , don't it? To be A few degrees Celsius is all that's
111:11 . And the basic idea is you the amount of sunlight that hits the
111:16 and this is all controlled by these cycles reflect changes in the Earth's position
111:22 its orbit. Okay, You can get changes the gross elevation. The
111:29 of course the melancholic cycles Milicevic was Serbian astrophysicist, recognized that the public
111:35 of the earth. So sometimes it's more vertical about 21.5°. Sometimes it's tilted
111:42 bit more away from the sun at a half degrees and the more vertical
111:47 the warmer the polls and the more the Earth is the cold. The
111:52 , which the angle of sunlight is and so the polls become colder when
111:57 angle of sunlight is higher, the become warmer. In addition, the
112:04 of the, of the earth's orbit . Sometimes it's more elliptical and sometimes
112:09 more orbital and that's called the eccentricity it varies At 100,400,000 year cycles.
112:17 called, we called it the short the long egocentricity cycles. The shape
112:23 greatly exaggerated these diagrams and in the in addition the orbit of the
112:29 the actual the actual pole of the prescribes a circle called the procession.
112:36 that changes at scales of uh Um scales of about 20, 20,000
112:46 The public is about 40,000 years. you've got the the processional cycle which
112:53 the the circle that the axis of makes. You've got the liquidity which
112:59 the change in the tilt of planet . And you've got the departure from
113:03 . If there's orbit once again, , we have three frequencies that either
113:11 or destructively interfere. When they constructively , the world is either much
113:16 It works much colder and when they fair then they kind of counteract each
113:22 . So that presents this composite curve fundamentally drives glaciation. Okay. And
113:30 is the composite curve For the last years. And sometimes public witty is
113:37 important, sometimes eccentricity and it changes geological time. Okay. So ultimately
113:45 helped Exxon and asked answer the we know there's a structure but is
113:51 any reservoir rock on. Okay. applied wheeler's concepts to seismic cross sections
113:57 explode them and start and start understanding on the basement which shifts and on
114:04 when sea level was low, high or falling because they observe the similarity
114:11 patterns of these laugh out relationships between that said wow, sea level is
114:17 up and down on both sides of and of course it is the atlantic
114:21 goes up and down as a function glacier used to see. So they
114:25 that the synchronous, the synchronous synchronous or synchronicity of the online relationships must
114:33 driven by used to see rather than because they weren't a social with angular
114:37 conformity. So this allowed them to in a basin with maybe no wells
114:43 all. And purely on the basis the laptop patterns begin to estimate the
114:48 of the rocks in the basin. was a fundamental breakthrough for them because
114:52 can start to predict, oh that basis dot source rock that base
114:56 reservoir. And they didn't need any data in order to start making those
115:03 and eventually they began publishing their sea curves. But of course when they
115:07 the first scene of the curves because were Exxon, they couldn't release the
115:13 data on the basis of which the level occurs were made. And this
115:18 a lot of scientists, even colleagues mine like Andrew mile to be deeply
115:24 of Exxon. In the end, think the academics lost 30 day.
115:31 , I'm just gonna show you a of examples that I finish up,
115:35 an example of some three D. interpretation of one of my students,
115:39 got cross sections different strike on on on the left and middle and then
115:45 views of a big programming shelf delta on the right here is the
115:51 size of the cross section beautiful Kana farms. The student picked the
115:56 surfaces based on the lap out So maximum flooding surface, A down
116:02 surface that was interpreted as a fallen sequence boundary. one that a transgressive
116:09 over land by a transgressive mud Another maximum surface followed by a sequence
116:19 with the next programming delta. And there was a little forced regression surface
116:24 the middle of this delta. You see there's lots of growth faults in
116:28 . Okay, It's a lot of sediment deformation in that falling stage low
116:32 delta. And that could be used interpret the system's tracks. So the
116:37 stand early, low stands late, stand transgressive and high stand right?
116:43 is work that you guys will be soon. Okay. And then ultimately
116:47 can stick that in the wheel diagram this case, compare it directly with
116:52 use static curve based on the auction for the last couple of 100,000
117:01 Of course, what we're gonna do in the next lecture, which will
117:05 our last lecture today to start thinking how we correlate and and interpret sequences
117:12 well on data. And here we a well log data from Guy clint
117:18 the Alberta basin. And you can beautiful Kelowna forms. There are some
117:23 forms, you can see that they're laughing other forms of different shapes.
117:32 can maybe see some sized valleys here are truncating units on either side.
117:39 a little hard to sing another value . That's truncating all these marine para
117:47 . Okay, um there is some like right here. He's got on
117:54 of a low stand delta on this here and you can make that back
117:59 incised valleys elsewhere in the cross This, believe it or not is
118:05 well logs. These are well logs the Carthage field in texas. This
118:10 a work work done as, as of my master students at University of
118:14 Jared Hammett. He lives in west and works for exploration companies there and
118:19 a nice example of a program programming aggregation als to strongly pro invitational back
118:27 appropriation a little retro rotational, pro aggregation als and then finally a retro
118:34 set of platforms. So a nice of stacking of cloud of forms based
118:42 well log data of course. What want to do is give you an
118:45 of how you correlate well, well data to do an interpretation that seeking
118:51 graphics like this, the various colors the environments of deposition and you notice
118:58 the students got shot SAm lines representing non chronic strata graphic gradation, als
119:05 little faces boundaries and the black lines the various flooding surfaces and then the
119:11 lines represent some of the sequence. an example of data from some more
119:17 my students. This is outcrop data the fair and sandstone in Utah,
119:23 shales. The base, nice platform and gray and yellow over land by
119:29 channel belts and orange inter bedded with muds in purple and then black holes
119:36 black. And then the white area is all marine show. And there's
119:45 this is based on an outcrop So the vertical lines here are measured
119:50 , the vertical answer a wells. vertical lines here are well logs.
119:56 . I'm just showing examples of photographic interpretations based on something other than
120:02 data. So this is now a more geologically oriented data. And we
120:09 start looking at the, you we can we can start looking at
120:12 trajectory of the clot forms. It's here, we can see that it's
120:18 . There's another grading to pro grading that it degrades down to that
120:23 It starts to degrade the back steps the way back to here. Then
120:29 pro grades down steps grades back retro grades. So we can start
120:36 at these at the stacking patterns. program. Additional degradation along retro rotational
120:44 we'll review that more as we continue discussions and of course eventually you can
120:51 the geological cross section and turn it a wheeler diagram in order to.
120:56 we've got time on the vertical axis are the absolute ages that we obtained
121:03 analyzing the volcanic ashes that are inter with the done bait with the fair
121:08 sand stones. Okay, so what sequences are made of? So,
121:16 know, the first sequence it was a big tectonic and conformity, ease
121:20 floss. They've evolved, evolved in seismic sequences and eventually the strata.
121:27 sequences of the Exxon research group that going to lecture on next.
121:33 And what I will say is when started looking at seismic data and reinterpreting
121:40 data, it resulted in platform geometries looked much more like seismic lines vs
121:51 old seasoning literature, photography based on cut offs of the 50s, 60s
121:58 70s. Right, So the fundamental that sequence geography solved is the integration
122:06 the understanding of key bounding surfaces and photography in correlating rocks as opposed to
122:14 with ology and zigzag shots. Um . Okay, so I'm gonna end
122:22 . Okay, so we'll take another . Okay? Or maybe I've got
122:30 10. So let's come back in 10 minutes. Okay. F Y
122:37 I'm not driving too to the States . We're gonna pack tonight and leave
122:42 . So I think we'll go right until 5:00 My time if that's
122:48 So we'll we'll start the next lecture on sequence triggering. I don't think
122:52 finish it. I'd like to introduce of the basics of sequence photography before
122:57 finish today. Okay, so let's a 10 minute break. Then we'll
123:00 back in about 10 minutes. It's . And I admit I always get
123:14 little messed up on the time difference here and texas. So I realize
123:21 a 4 30 here in my time 3 30 your time. So we're
123:27 go for see if I can get this this lecture today and then we'll
123:33 that will be kind of wrapping I don't want to get kind of
123:38 this one before we break for the . Any questions about anything I've talked
123:45 so far, You know, this today is a bit of like a
123:50 lecture heavy. A lot of ground cover. It'll not that we won't
123:54 more lectures later. But these are of the sort of very basic things
123:58 I want to make sure you guys getting it. So sequence of geography
124:04 the there's a lot of ways to at it. Modern sequence photography as
124:09 of developed by Exxon. To give the credit was really the application of
124:15 strata graphic principles, two geological data as outcrop core well, logs uh
124:24 and the publications of sequence photography. revisited some of the stuff that we
124:29 about that Burrell had figured out in of base level control but revisited it
124:36 perhaps refined it, leading to a understanding of how de positional systems change
124:42 a function of the forcing parameters that is sedimentation rate or settlement supply and
124:52 . We've already done that were, know, in some ways. I'm
124:56 explaining that to you. You I started with that because I think
124:59 you understand how sedimentary systems build it it much easier to understand the
125:07 So, this lecture will be a more about just reviewing the terminology of
125:13 photography with the with the hope that got an understanding for the processes based
125:20 the exercises that we've done so Mm hmm. So, simple equation
125:30 . So, another way to think sequence photography is that it's the rocks
125:35 don't like the word rocks. You put you know what the word
125:46 you can put faces in there. is kind of a geological term for
125:53 deposits, if you like. Clarion on surface and clearly understanding that the
126:01 have meaning in terms of time. , here is a definition. The
126:06 of rock relationships. So there's the within the corona strategy framework, there's
126:13 time we're in the succession of rocks cyclic and it's composed of genetic related
126:18 units. This doesn't specifically have the surfaces in there that's kind of implicit
126:24 the repackaging of the rocks into units by un conformity, ease their corrosive
126:30 , corrosive conformity ease. That gets into this idea that there are surfaces
126:37 sequences consist of of systems tracks that interpreted in terms of changing the accommodation
126:43 accumulation, which is the very first we did. So I started going
126:48 circle, but there are there are definitions. I won't go through these
126:55 they more or less all say the thing. Okay. You know,
127:00 of cyclic sedimentation patterns develop a response variations and sediment supply and space available
127:08 of sediment response to changes in base that result from the accommodation sedimentation.
127:14 they're all saying there are strata, patterns that reflect changes in the ratio
127:22 kind of saying that same thing. , this is a diagram. This
127:29 a diagram from the original, one the early 1980 for publication in sequence
127:35 and it's a pretty rough figure, it is an original. I just
127:39 it up with code pens, never redrafted it digitally, except that
127:43 some better known. And so, know, this is an example of
127:47 typical lithia strata graphic depiction as we , you know, a sort of
127:51 Galloway Hobday Martini sort of 50, 70s description, you know, a
127:58 of transgression regressive tongues into fingering of stones and shells. And then this
128:04 of sandstone that's kind of stuck out the middle of the basin. It's
128:08 really clear what relates to walk. we started to put the key surfaces
128:13 there. We realized, oh, a low stance, submarine fan that's
128:18 to this un conformity, that's in middle of this classic wedge here.
128:23 there's the classic wedge. And we and we said, okay, there's
128:29 un conformity in here that actually goes these shales and allows us to link
128:35 sandstone with this turbo light sandstone this down here. So the sequence topography
128:41 allowing us to link things on the of correlation of surfaces that are hard
128:46 understand the linkages without those surfaces in , you know, without the
128:52 We don't know whether whether this sandstone linked to here or here or here
128:57 walk, right, okay. And course we've got, what is this
129:08 , anybody and then what's this relationship ? That's very good. So,
129:29 know, it's it's it's it's you how the units are on lap in
129:33 in sequence one and then the on shifts toward baseball position and that's because
129:38 the drop of base level that that this un conformity here. The un
129:43 is flu avian flu real here, sand, on sand and here.
129:47 a little bit easier to see you've marine sand on marine shales implying a
129:52 would shift of faces and a deposition shift in the position of on
129:57 helping us to define the sequences next and take that cross section and exploded
130:04 a time strata graphic or were We can say that despite the fact
130:10 and this part of the base and there's a flu really influential contact,
130:15 a there's a major strata graphic gap marking that PSA burial hiatus. Now
130:28 wheeler did his original wheeler diagrams, know, he liked to have sequence
130:34 sequence be and then he shows the . This is one of one of
130:40 1964 papers who identified there was a uh nonconformity at its core relative continuity
130:48 what we would call uh conformity. he would define, you know,
130:54 there's the time gap with all sorts complex terminologies we're not going to worry
130:59 right now. But this idea of level transit cycles that tim cross and
131:04 students picked up on, we've got sequence a in blue, a sequence
131:10 yellow and that he would draw an vertical boundary at the tip out of
131:14 un conformity and make a sequence K the next on did I said let's
131:20 continue the un conformity conformity and let's have a sequence A and a sequence
131:27 . And will ignore this vertical cut and sequence K. Mumbo jumbo.
131:32 it was it was that little breakthrough Exxon of continuing the corrosion of conformity
131:37 they could easily see those in their data that was the big breakthrough that
131:41 sequence attribute something that was kind of in this obscure literature that very few
131:47 read to something that everybody now practices is the star ground again, showing
131:54 schematic cross section with two sequence barry shown in red and there is the
132:02 in wheeler space. The dash lines the correlative conformity ease. Okay.
132:08 the reds represent the gaps in time which there is a gap in which
132:13 is no record, no rock record those periods of time. Okay,
132:19 sequence is the is the group of between the two and conformity. So
132:27 a cross section below and the wheel I'm above. But the last thing
132:32 did is that is they they recognized on lap pattern but then they said
132:38 a minute, it doesn't make any for sea level to rise and then
132:44 fall. In fact, if you at the isotope curves, it looks
132:48 sea level, basically falls slowly and very rapidly. So in terms of
132:55 used to used to see the rises typically rapid and the falls are more
133:00 . But they noticed these soft tooth based on their cross sectional data and
133:05 they realized that they were missing is weren't thinking about the compassion all and
133:10 subsidence. So when they start to at the at the on lap patterns
133:17 the creation of accommodation as a result on lap and then integrated that with
133:22 subsidence curve. The leftover accommodation change the use static curve and that had
133:28 smooth appearance compared to the on lap . Okay. And those are the
133:33 and that was it. So originally would show coastal on lap curve eventually
133:38 extracting the subsidence using back stripping NGO . They were able to extract what
133:44 believed was the use static signal. . So there is a variety of
133:51 sequences that have been defined. The group defined a deposition. I'll sequence
133:58 a relatively conforming succession of genetically related up, battered by their un conformity
134:05 or could there correlative conformity? So need to unpack that definition a little
134:11 . We've already explained what nonconformity is I've explained their breakthrough in extending it
134:17 the corral of conformity. But what this mean relatively conformed? Does that
134:22 conform along? Mostly? Can What about genetically related, genetically related
134:27 what to an advantage of deposition to sea level change? So they didn't
134:33 a particularly good job of defining the of relatively confirmable. And we can
134:38 that means no major strata graphic But although I don't dislike this,
134:44 they don't really explain what what they by genetically related succession of genetically related
134:52 . Because the word genetics comes from word origin or genesis that typically means
134:59 because of what process. Right. Galloway to find ah genetic strata graphic
135:08 distinct from de positional sequences at the units between maximum flooding surfaces and ashton
135:15 got in the game and separated and sequences according to whether settlements transgressive
135:22 Uh So he had tr sequences. right. So this is the original
135:28 diagram from the external research group. so there may contact with the sequence
135:35 . These surfaces that form as a of sea level dropped and exposed nick
135:41 and allow rivers to incised valleys. we discussed when we talked about base
135:45 concepts, uh Following sea level you get you get a basin would
135:54 in the faces, basin would shift on lap and the deposition of the
136:00 sediments and submarine fans in a much basic position. And this entire wedge
136:07 red and purple is on lapping is lapping in a more medial position.
136:13 the high stands extended for landlords and surface that bounds that low stand unit
136:20 the purple surface. It marks both maximum regression of the shore line below
136:26 surface and above the surface everywhere the are deeper. So it's both a
136:32 regressive surface below and a transgressive surface . Okay. And then as the
136:39 continue, you should get this back of units at some point, you
136:44 the maximum seaward, the maximum a migration of the of the sea
136:52 that of course marks the maximum starting and that marks the top of the
136:57 systems tracked after which the systems begin pro grade again. And the transgressive
137:03 track is characterized by a retro gradation our stacking pattern as we talked about
137:11 . Okay. And so the observation those surfaces and associated laptop patterns define
137:19 three major systems tracks. Now there others, but let's start with the
137:24 and then we can add more as feel necessary. So the low stand
137:29 tract has a sequence span the base maximum of progressive surface or transgressive surface
137:35 the top. Then we see a of back stepping units that mark the
137:41 systems tracked that show a retro gradation stacking pattern and then the system turns
137:46 and begins to move seaward again or . And that defines the high stand
137:50 tracked that continues until the next drop sea level. That cuts a new
137:55 dis conformity internally sequences of build of upward cautioning units that are referred to
138:05 paris sequences. That's another term that introduced by van Wagner. There's lots
138:11 people trying to get rid of the power sequence. I find it fairly
138:15 and I'll explain what it is in a bit Now, back in
138:26 I forget what it was 88 Bill Galloway got really upset with the
138:33 research group and he put together his version of the Exxon slug diagrams.
138:40 this is Exxon's diagram published in a written by Exxon employees. This is
138:46 same strategic graffiti but published by Bill who's a professor at Ut Austin and
138:54 Galloway worked primarily on well, logs the gulf coast and Exxon and particularly
139:00 Wagner had don't want to work in book cliffs, working on rocks and
139:05 . And so part of the differences opinion was based on the databases that
139:10 used. What Bill Galloway noticed that well off as you just saw these
139:15 course from units very short contacts going shale. Right. And he said
139:20 flooding surfaces are really easy to So, you know, because it's
139:25 to pick flooding surface and well He preferred to build a sequence photography
139:30 flooding surfaces as the mainstay photographic He felt that the sequence boundaries were
139:36 difficult to identify and he showed them with these sort of dash lines.
139:42 , in contrast, he showed the flooding surfaces and drew them with a
139:47 black sharpie. Okay, so the is exactly the same in both of
139:53 examples. There's no difference in the in the lap out relationships. The
139:58 difference is the thickness that the presenters to depict the importance of the
140:04 Galloway uses a dashed curve to show sequence boundary even made the mistake of
140:11 a dash curve below the incised I'm like no Bill, if you've
140:15 flu viel rocks eroding into marine I'm sorry, that's easy to pick
140:21 a well log and an outcrop in core. So I actually disagreed with
140:26 this as a dashed curve. So actually didn't give him the benefit of
140:31 there, but he showed as a and I think he showed some of
140:35 is a dotted line. And so thought he was maybe a bit aggressive
140:38 in how uncertain he was in drawing sequence, found things and I think
140:43 got his daughter here but he felt clear that these maximum flooding surfaces were
140:49 easy services to pick and therefore driving with a thick black line. You
140:53 that that they're they're drawn in this with a dash line. Right.
141:00 there's no difference in where the surfaces . The only difference is that the
141:04 of the pencil or pen they use draw the line. And so,
141:08 know, the question becomes, is really any difference between an Exxon de
141:13 sequence and a bill Galloway genetic graphic sequences other than the thickness of
141:18 sharp as you used to draw the . Okay, so not a big
141:24 . A lot of ink was was expanded on that. Now there is
141:29 concept of type one versus type two . Okay. And in a take
141:35 sequence Sort of type one sequence, scene of the fall is so
141:41 But the shelf float break is forming a knick point and allowing valleys
141:46 in size. Okay, if you a sea level fall. So there
141:57 there is sea level is rising and central falls from this to that
142:05 but not enough to expose the shelf break. And then the system
142:10 These are what Excel referred to as Type two on conformity. You notice
142:15 the type two in conformity there is on lap a basin would shift and
142:22 lap at the type to sequence there's lap out there but there's no
142:27 incision of the rivers because there's no exposed. So basically it's a ca
142:34 conformity there and it's an un conformity And unfortunately that part of the base
142:42 not always very obvious. So tough excellent. Type two sequences are are
142:47 but they're actually pretty difficult to Now this diagram is so confusing,
142:57 want to spend too much time in . This comes from the textbook written
143:01 Octavian, Catty, Mariano and octavian very focused on terminology and so on
143:08 diagram. He's got a variety of , the maximum flooding surface, the
143:15 progressive surface which is the old Exxon surface. Um Then he's got the
143:26 surface of forced regression which I mentioned the regressive surface of marine erosion.
143:31 kind of equivalent the corral of conformity he's got. What else does he
143:38 in here. Mhm. Anyway and he's contrasting the tr sequence of
143:53 which is simple, coarsened up with upward. The surface from severe lung
143:59 is too severe lung conformity that would the de positional sequence of Vail and
144:06 the uh and then the the maximum surface to maximum flooding surface. That
144:13 define a Galloway genetics equals. So just showing the different types of pics
144:20 and importance of surfaces used to define conformity ease in the in the different
144:26 of sequence photography. I don't pay attention to this. I understand it
144:33 I basically kind of do my own depending on what the data tells
144:38 Okay, having said that, you , all these surfaces can be recognized
144:43 on the quality of the data that have Gabe. Then we'll talk about
144:47 aggressions in a separate lecture next I've already talked about the maximum flooding
144:55 area and conforming sequence boundary. It's conformity as well as this maximum progressive
145:02 . The next song referred to as transgressive surface. Those are synonyms essentially
145:08 is a sequence family tree. The first sequences were defined by Larry Sloss
145:15 1949. It actually slows crumbling and And then mapped and codified in his
145:22 63 paper. Then they were picked on by Mitchum Who sort of followed
145:28 63 and wheeler and then sequenced really to break up. There are a
145:34 of, a lot of discussions As whether whether there there should be a
145:41 systems tracked. The force progressive or stage systems tracked and that resulted in
145:49 the deposition of sequence for of clinton model and hunting tucker who identified forced
145:55 and fallen state systems tracks versus the group that's stuck to a more or
146:01 a three component systems track and then people abandoned the sequence banners altogether and
146:08 no flooding surfaces are more important. then Ashton Embry tried to make the
146:12 . Now it's just transgressions and Um I could go into a long
146:20 about why we have all these differences opinion about how complicated or how simple
146:25 should be. I'll tell you point . Ashton Embry is a good colleague
146:32 mine. He spent his entire life in the geology of the arctic
146:38 He has almost no data. His seasons never lasted for more than a
146:42 of weeks because that's about the amount time that he could afford to helicopter
146:46 the helicopter helicopter up there. So a consequence, Ashton Embry works in
146:51 very data poor environment and he just have the data to define the complexity
146:58 someone like bill Galloway who has a well locks but bill Galloway and
147:02 I know bill Galloway well bill Galloway almost exclusively with well logs as did
147:08 never looked at a lot of core so they were never really able to
147:12 into the detailed distinctions of waffles law changes that for example, I was
147:18 to do what I did sequence So they're sequenced rigorous work. If
147:23 got sparse datasets or just well logs some of these other sequence tributaries reflect
147:28 robust data sets. Now, we have some questions about the definition about
147:40 nonconformity is. So Mitch Sherman Etienne 77. And it's important to understand
147:48 when Mitchem defined nonconformity, he he make a mistake. But you
147:56 someone publishing their seismic photography, they understood that there's lots of tectonic on
148:02 . These they're like, no, not talking about those were specifically talking
148:05 un conformity. These that are a of drops of sea level technically as
148:11 talk about in just a minute, are actually legally speaking, disk
148:18 not angular on conformance that has been lost in the literature on sequence
148:34 But anyway, so Mitchum defines it the surface of erosion or non
148:38 Fair enough. That separates younger younger , the youngest trainer from older
148:44 The assumption, of course, is older rocks are below the conformity and
148:47 younger above and represents a significant There's got to be a a missing
148:55 time. And then interestingly, he his comment at least a correlate herbal
149:03 of a geo chronological unit is not by strata. So that's an important
149:11 that there is something in terms of photographic units of bureaucratic logic units that's
149:17 missing addition. He points out that of erosion and non deposition occur and
149:24 associated with global falls of sea level produced these un conformity ease that can
149:29 traced in between regions. So on sides of the atlantic ocean.
149:35 so let's make sure we understand and that a little bit. Okay,
149:42 I want you guys to try to your thinking caps back on a little
149:46 . I know it's getting late in day. I know how you
149:50 But let's go back to a, does he mean by a core available
149:57 of aji a chronological unit. Can tell me what you think that means
150:03 terms of what I've discussed in the two days, particularly this morning.
150:13 they are related either by the love originality. So this um the geo
150:23 units are related genetically or either by . Either they have the same Youtube
150:31 or they were deposited from. I'm at it in the I summon one
150:40 give us. Yeah, I think think I would I would step away
150:45 that and think about how we define strata graphic units. Right so this
150:53 goes back to the different types of And I talked about when he says
150:57 a geo chronological units not represented? does he mean? What's missing?
151:03 you think he means? Maybe can give me an example of a geo
151:16 unit that I talked about earlier One of the examples of the geo
151:21 chronological units. That's why I went this this morning in order to understand
151:33 foundational definitions of sequence photography, we to be able to link it back
151:37 the more traditional types of particular they about earlier today. If you look
151:44 a bunch of rocks, there's a what's missing at the un conformity a
151:51 of time. Yes, we know time is missing. But how is
151:55 determined by using what other kinds of graphic analysis? How do you know
152:02 time is missing in a contact using a strategy gritty, definitely not with
152:09 photography. That's the one thing we wouldn't use. And he's not talking
152:16 that using waters law. He's definitely talking about walter's law, that's a
152:22 finer scale than he's interested in He's talking about big global regional and
152:28 ease the scales of millions of Fyi keep going. You're doing good
152:39 the earth's magnetic field. That could because remember we had about 30,
152:44 , 60 changes at 250,000 years. that could be one but by and
152:51 oil companies aren't doing magnetic analysis. . What are they doing bios
152:59 They're looking for missing buys owns. . Remember I went through the duration
153:04 species and you know if you get chance to take the the advanced course
153:11 that that Don and Pete teach. will give you a feeling for how
153:16 smallest amount of time you can resolve bios photography. So fundamentally what Mitchell
153:21 saying in this massive teamwork at Exxon if they could demonstrate missing bio
153:27 that's how they demonstrated that a chronological is missing because of, you
153:32 the smallest Chronos trotted graphic unit is stage below that you're down to bio
153:40 . Okay. So he so he use by zones there. He wanted
153:44 keep it generic, but he's what really saying is, is is we
153:49 correlate that there's time missing by using bias photography team. Okay. And
153:57 know, and that means he's talking pretty big picture things. Okay,
154:01 you're talking about 20,000 years sea level , there's nobody who's going to help
154:05 with that very much. Okay, Mitchum is talking about seismic photography,
154:12 sequenced photography. Okay, that's Now Van Wagner came along and provided
154:20 revised definition of un conformity as a separating younger from older strata fair enough
154:29 which there is evidence of psa irrational truncation or severe in exposure.
154:36 there could be erosion by rivers or a paleo saul or a car surface
154:44 submarine erosion. That's correlative to the erosion in some areas also indicating a
154:52 hiatus, again, what's a significant that which is resolvable by by photography
155:01 maybe to go back to Mcdonald's suggestion hiatus is simply proved by truncation,
155:08 ? If you see erosion there must something missing, something's been eroded
155:13 But maybe only eroded away five days settlement Or maybe it's five millions years
155:18 settlement. And how do you know absolute amount of time for that?
155:21 need some chronic chronic metric control or photography. Then he goes on to
155:28 that unconfirmed his form in response to relative fall of sea level. Now
155:35 is a bad definition of the word conformity. Gabe. It's much more
155:42 than the Mitchum definition. Okay. and uh it's it's got some problems
155:50 them. Now here's the deal. sea level falls and you expose the
155:55 point rivers will cut an incised We talked about that yesterday. Other
156:01 were exposed to the air and may a soil and if it gets fossilized
156:06 be a pair of yourself. And and so it's certainly true that
156:13 relative falls in sea level can, cause the formation of sequence standards.
156:18 can also have tectonic deformation that can major submarine angular and conformity but they
156:26 not satisfy this Van wagoner definition like . I talked to our for that
156:33 mobile he said, yeah, I we hated that definition of, of
156:37 from Van Wagner because it excluded Marie and excluded tectonic and conforms. So
156:44 I would say is if you make observations that Van Wagner explains that certainly
156:51 compatible with with identifying some types of conformity ease. But it's not a
156:57 universal definition of the word on conformity it's it's definitions like these that drove
157:04 academic community crazy because wait a These are all in conformity that are
157:10 by sea level fall. This ignores on conformity is what's wrong with these
157:15 . Don't they know that when you and fold rocks, you get on
157:18 ease that have nothing to do with level change. What's wrong with these
157:22 ? Are they nuts? They're ignoring conformity. These But now what these
157:27 said to themselves is of course we that. But I mean any any
157:32 geologist knows that about anger on conformity those are the easy ones. We're
157:37 about these much more difficult on conformity to identify the rock record than the
157:42 of Sanibel falls. It takes a more skill to identify a dis conformity
157:47 an angular conformity. But they don't that in their papers because they don't
157:53 to tip their hand that they're very in tectonic analysis and because they're in
157:58 company and don't need to be concerned academic peer review. They got away
158:03 publishing a lot of papers that appeared ignore or under plate tectonics and that
158:09 a lot of academics angry. now there's also buried in these in
158:17 definitions. The idea that these that sequence boundaries the excellent sequence boundaries which
158:24 basically dis conformity ease everywhere, separate the rocks below from under younger rocks
158:32 . I have done a lot of that demonstrates unfortunately, that's not true
158:39 and that's resulted to some papers I've , which are on the web.
158:42 argues that some of these dis dis ease are not actually in conformity at
158:49 . They're very diaphanous and I'll discuss a little bit later in in a
158:56 by the next week on our last together. So this is a diagram
159:01 a basic under graduate, strategically This is the box book that I
159:07 A Diagram that goes back to 1957 it's as valid in 1957 visitors
159:13 And this shows the four basic kinds un conformity. Okay, you've all
159:18 pretty good at identifying and anger on . And that superimposes relatively or rocks
159:28 are that are folded and have an discordance with the rocks above. At
159:34 time of formations. And these of , by definition of tectonic in
159:39 you have to have deformation of the sphere or of crustal rocks to produce
159:45 on conformity. Whatever the defamation could be growth, false rifts,
159:49 . All regimes a dis conformity is undulating erosion all surface. Okay,
159:57 separates rocks that are internally confirmable above rockstar, internally could fall below.
160:04 the flat line the rockstar flatlined above they're flat line below. But the
160:10 difference is that this undulating erosion. dis conformity separating them them. Obviously
160:17 no angular discordance. That's a very kind of un conformity that's called the
160:23 conformity. Okay, then we've got nonconformity which is defined where you have
160:29 rocks overlying non sedimentary rocks such as or metamorphic. And then you've got
160:36 thing called a para conformity. The para means almost. And here's where
160:41 got flat lying rocks overlaid by flatline with no evidence of erosion along
160:49 And the only way to identify para would be bye bye strata. Graphic
160:54 that identifies missing bio zones. the paradigm for me is not quite
160:59 same thing as accredited conformity. Para would still have missing bio zones at
161:05 contact. The modern deposition of sequence is foundational, focused on dis conformity
161:15 I don't think that's widely understood in sequence data graphic literature, but it's
161:20 to understand that okay, now of , you know, in in a
161:27 , you know, a nonconformity can into a into an anger on
161:33 into a disk conformity and eventually become . Right? So one type of
161:40 can transit into another. So that's thing to keep in mind. Larry
161:47 was foundational, focused on angular and . Big regional angler and conformity ease
161:53 define these tectonic strata, graphic Okay. And of course he based
162:00 work on Blackwelder who did the same . Okay. And we talked about
162:08 and larry slots was the very first to use the word sequence. It
162:15 from the 1949 paper. Bye sluss , Bine and apples, published in
162:21 Geological Society of America memoir. And his sequences were interregional rock units.
162:26 rock units that could be created credit large areas complying assemblages of formations and
162:34 . So there were units that were than formations and groups, but by
162:40 recognizable horizons, commonly strata graphic, . Yeah, but without a specific
162:49 significance. In other words, the strata graphic the time varied widely from
162:58 to place. More time in the of the continent's less time in the
163:04 . Okay, now what sequence should good for? Well, It's been
163:11 for two fundamentally different things. One to use lap out patterns to predict
163:21 age of rocks. That was one the major uses by Exxon back in
163:28 70s, which to get seismic data under basins and use the on lap
163:34 to predict the ages of reservoir source seal pre drill. To try to
163:39 the uncertainty of the risk of those portfolios. And the other use of
163:46 photography is a tool for correlating and where faces are. Okay, and
163:56 a little bit more on the second . Uh because I'm usually working below
164:02 level of age data. So backing the question, what are sequences NATO's
164:16 like many things in geology, there's simple, universally accepted answer and there
164:24 competing camps. So, yes, was very I was trained in
164:33 And of course most of the professors taught me came from the european school
164:42 of announces of rocks with a bit texas thrown in. And so you
164:47 the Oxford McMaster group. It was focused on environmental faces and you can
164:54 a section and lump those into faced . You could correlate these using well
165:00 to map de positional systems which very came from Bill Fisher and jo Mcgowan
165:07 of Economic geology And then exhale one man in particular uh mentored by
165:21 Campbell identified that there were surfaces in scale Lana. So millimeter scale layering
165:29 surfaces, two beds, two bed to paris sequences and para sequence sets
165:34 sequences. So we have a hierarchy 1234567 things. And sequences could be
165:41 into sequence sets and composite sequences. then the the european european texas
165:47 you've got faces that can be grouped faces associations to define de positional systems
165:53 they build systems, tracks and So we meet up with sequences but
165:59 the lower levels we've got very different of approaching the description of sedimentary rocks
166:05 build sequences. Okay, this hierarchy completely based on surfaces. Part of
166:13 question is are there any surface is to identify faces and faces associations and
166:19 positional systems. Systems tracks and sequences absolutely, definitely defined on the basis
166:25 lap out relationships and sequences. What these smaller things. So part of
166:30 struggle struggle is reconciling these different schools approaches to describing and interpreting sedimentary
166:40 Initially back in the 70s, the was very broad size of photography and
166:47 defined hi stand and a low step based on this observation of on lap
166:57 . And that was the the diagram Henry Postman Terra showed in the last
167:04 . Right. And that defined a standard and high stand Systems track.
167:11 later on they said wait a Within this thing, we're calling the
167:15 stand. There seems to be a between things are retro grading versus pro
167:24 and that seems to correlate with this line I've drawn here, that's the
167:29 flooding surface. So initially there are systems tracks. The high stand,
167:33 stand and then they broke the high into a transgressive and a high stand
167:39 tracked. Okay. And that of led to the slug diagram that I've
167:45 in some detail. Now, the term that van Wagner introduced was this
167:53 of the paris sequence. Okay, I've already explained this when I talked
167:59 waffles law. So para sequence is similar to the concept of the theses
168:14 . Now faces association and the lateral vertical. If you're measuring a core
168:23 an alcohol. We typically measure the going from bottom to top and you
168:27 up a vertical stack of faces, call it a facie succession. If
168:32 correlate faces from one place to another , then you can build a lateral
168:37 dissociation. So walther's law says that vertical faced associations in order to face
168:48 successions can be linked to the lateral associations, such that the foreshore is
168:56 to a shore face that that grades a transition zone and eventually grades offshore
169:02 the muddy offshore faces. And we that in a gradual, of course
169:09 faces succession that conforms to well, law, when we see this contact
169:15 anonymously superimposes offshore marine shales directly on foreshore deposit. We have a contact
169:22 violates walther's law resulting in the flooding . Right? So in this case
169:29 flooding surface caps, the faces succession this new concept called a para
169:37 So, a facie succession is a stack of faces that represent a genetically
169:44 group of environments of deposition. And they are bounded by flooding surface,
169:50 facie succession becomes a para sequence. , they're very similar terms. That
169:56 sense. That making sense to you , I see an odd. So
170:02 good. Now Van wagon got the of a para sequence from an older
170:10 From the 1977 seismic volume of a cycle. So, in a sequence
170:17 cycle, you get, you get bit, you get on lap that's
170:22 landward, you get this abrupt basin shift what that looks like in terms
170:29 photography. Is this followed by So these are, these are on
170:41 here. That's a long lap. is on lap But the online has
170:48 from .1 to .2 and that's, recorded by the salty here. So
170:54 the only point there and it shifted . But they also noticed there were
171:00 that with the on lap then the kind of slowed down and then and
171:06 and then it accelerated again, slow and accelerated. But there was no
171:12 of a basin would shift in So they interpret these as periods of
171:16 level rise, still stand and then rise. So some of these don't
171:21 the disk conformity. These right, a rise of skin about stops and
171:25 continues to rise. So they they call those para cycles. So
171:31 not rise and fall. It's rise down, slow down and then rise
171:36 and they call those parasite als. no evidence of intervening fall as a
171:43 that results in units bounded by flooding but with no evidence of, of
171:48 exposure, incised valleys would expect if was a full fledged uh cycle of
171:54 level change. Anyway, that's where term comes from. Para sequences could
171:59 oughta genic in origin. I'll talk that just a bit and critically.
172:03 followed waffles law. That's why I'm track of what I said yesterday.
172:10 . That's why I think was was yesterday I talked about walter's law and
172:13 to explain that context. So here can see here is a series of
172:17 stones going to sand stones, there's surface, but stone stone, the
172:22 stones and you have to trust there's another flooding surface on top of
172:27 . And so these could be procreating faces programming delta lobes or maybe a
172:33 upward carbonate cycle. And again, an example of a shallowing upward programming
172:41 face deposit in schematic view. And course, if we measure these sections
172:46 muds, little sandstone, mugs, , thicker sandstone, thicker sandstone.
172:56 then finding the thicker side story flooding . And so you can see the
173:00 cycles here and here's some examples from textbook. So here we have the
173:07 cliffs with a series of upper course , short faced delta deposits. Uh
173:13 drilled wells behind these outcrops. And you can see the para secrets quite
173:19 . It's mud stones here. You start to see a little grated sandstone
173:25 there. You can see sandstone and there's a nice surface here with a
173:30 juxtaposition of marine mud stone over shallow sand stones, you go back to
173:36 inter bedded sound stones and mud They question up in the sand
173:41 Once again, you get a surface separates mud stones above from sand stones
173:47 . So we have to flooding surfaces these two para sequences the lower one
173:56 the upper one that show these nice up the profiles in the catalogs.
174:01 . And the gamma rays in decreasing increase in sand upwards. The lower
174:06 has muds. That sounds at the , right. There may be evidence
174:10 a little pair of sequence boundary right . That could be that one.
174:14 it's muddy or the sand here, it goes back to money or barter
174:19 . Then it goes into sandy units all these bars libations in them.
174:24 you start to see cross bedding indicating shore face. We've got some mud
174:29 ups, maybe some channels. And there you've got the contrast between marine
174:34 above and sandstone below. So sandstone to mud stone and that of
174:39 is the flooding surface and it's expressed a pretty sharp contact. There is
174:44 of finding upward. So this unit gets muddier, although it's not
174:52 Now, here's a close up of car here you can see the cross
174:57 which is upper shore face deposits. , what's interesting is here you can
175:03 an erosion all contact with bar debated in between bar debated marine units in
175:10 and then a sharp contact button puts the the the marine shale. So
175:15 that the marine shale is a So these basically represent down lapping pro
175:20 shales. So, if you imagine pro grading shore face looks like
175:27 that's just that's this regressive stuff Then waves come back across and maybe
175:37 that to green here, ways back back across and create an irrational surface
175:48 results in the deposition of this little unit here and then later on the
175:54 turns around and you get program nation another unit which puts marine muds on
176:04 of that transgressive lag. Okay, here's an example of the Mississippi
176:13 a nice lobe, delta lobe. rivers feeding in, you've got a
176:20 of sand and these well, logs beautiful upward coarsening faces successions in the
176:28 of the lobe. When you go the lobe, you see much more
176:32 upper coursing units because the sand didn't it out that far. And then
176:37 middle course here you see some evidence finding upward that might be the channel
176:42 feeds the delta. And then you see a good example of the flooding
176:47 that represents the abandonment of that loaf it sinks down and gets flooded.
176:56 idea that delta's go through cycles is understood. So a river deposits
177:04 Then the flow goes somewhere else. load begins to get attacked by waves
177:14 , because of perpetual subsidence. The of sinks below the scene. There's
177:18 wave dominated barrier that's the last remnant the old load. But eventually,
177:24 during storms, sand is washed into lagoon area and some of the stand
177:29 taken offshore. Eventually the whole thing below the sea. Okay. But
177:35 time they used to be alone up seven, years ago Then it switched
177:41 position two, Then three, then , then five and so right now
177:47 a little area of sand called ship Worth of six sinks ships sink
177:54 We got the Chandler islands that represents the Mississippi Delta was about 4000 years
178:01 . This used to be land where words are that sunk below the waves
178:05 course here you've got wave dominated shorelines are still attached the land Low five
178:12 there little bit more recently than And of course there is the modern
178:20 that's active active today. And of 1/3 of the discharge of the Mississippi
178:26 flowed into a trifle ebay building new . And of course these lobes switch
178:32 oughta genic lee. And if we course through these lobes, we would
178:37 these nice upper course inning para You can plot that leader space.
178:44 we've got time on the vertical axis thousands of years and there is the
178:49 marabou in slack uh slash um ah and the younger and there is the
178:58 day Belize plaque, meat logs and we could do wheeler diagrams of
179:05 which I won't go into today that the other kind of end here in
179:12 a little bit about five or 10 . So we talked about paris
179:18 The other thing that Van Wagoner noticed that power sequences can be organized into
179:24 . We've already talked about the idea a cloud FM being organized and
179:30 Als aggravation alert, Retrograde additional Okay. And if Van Wagner was
179:41 less with claudia farms, although his of paris sequences clearly show that they
179:46 a cloud of form geometry. And he just noticed that paris sequences can
179:52 retro gradation, allow aggregation, ALs pro gradation and provo national could
179:59 you know, programming Seaward degradation. is still as McDonagh's correctly pointed out
180:06 today degradation. Als is also pro . Okay. And retro vocational paris
180:15 can also have a partly aggravation So, if you just understand that
180:20 paris sequence sets, we're essentially the as as a combination successions. They're
180:27 fairly equivalent ideas. Now, this going to get us into another assignment
180:35 I haven't given to you yet, is the idea that if you sample
180:39 para sequence sets, an individual well can show these distinctive variations in the
180:46 that the parasite could stack vertically. paris sequences are moving farther away from
180:53 , they may they may appear to muddier upwards. If the paras sequences
180:59 building towards you, they may appear get sandy or upwards with each successive
181:04 sequence and you may get less mud the success of paris sequences. But
181:10 ragged aggravation. All each para sequence look about the same thickness and have
181:15 the same proportion of sandstone versus So this brings us to a fundamental
181:22 the observing the stacking pattern of individual sequences in one well log can be
181:30 to potentially identify para sequence sets, as we'll point out in a bit
181:38 traditional paris sequences commonly associated with transgressive tracked presentational decoration, A low low
181:46 systems tracks and probate and aggravation appropriation Hiestand systems tracks. So the idea
181:53 that these stacking patterns can be linked systems tracks and sequences. So it
182:00 us to look at one dimensional data potentially extrapolated to cross sectional data.
182:07 it allows us to start thinking about dimensional stacking and and and link it
182:12 to accommodation successions that we talked about . Okay, and so this is
182:20 a close up of of presentational para set. Okay, this is actually
182:26 to aggregation. It shows a well that shows muddier to sandy pair sequences
182:32 up with the green non marine But here's an example of what one
182:37 those might look like here. We've paris sequences that approximation along and with
182:43 dairy faces on top. Then the sequence set goes degradation als and we
182:49 our floodplain para sequences and we start get some sharp based units in this
182:56 section here is Van Wagner's example from book cliffs because he's broadly speaking,
183:03 is procreation with some aggravation and the sections from the outcrops show increasingly increasingly
183:13 pair sequences that ultimately turn into non . So here's para sequence one.
183:18 sequence to power sequence three. And sequence for. And you can see
183:24 broadly getting sandy or upwards here, very money. Then they get sand
183:30 . Sandy and sandals of course, can actually see that stacking in the
183:36 . So again, here is paris sandy, but your body is So
183:41 would be a retrograde retrograde additional para set. Then we go into the
183:45 stand with sandy. The next one sandy here, then it's eating sand
183:50 and eventually goes into thick stack of real rocks. Right? So we
183:54 see these stacking patterns vertically and we link those back the lateral correlation of
184:02 paris secret sets. Obviously, if have vertical aggregation, the para sequence
184:09 all the same on a well, here's an example of a vertical aggregation
184:15 sequence set from the valley in So we see a group of para
184:22 . The parachute is all more or and in the same position in the
184:27 . Okay, producing a nice aggregation stack of para sequences If they migrate
184:36 , we get that retro gradation of sequence set and the wonder one dimensional
184:41 expression of that. It's para Sequels get muddier upwards. They may also
184:47 thicker upwards because accommodations increasing upwards depending how much sediment there is to fill
184:53 the bottom. We have a nice section, This is the almond sandstone
184:57 quotations. I've had students work on , that shows a beautiful back stepping
185:02 retro gravitational para sequence set. The diagram, we just have some examples
185:07 some pro professional care sequence sets, upper one of which has a sequence
185:19 . And then finally, we can at the paris sequence sets grouped into
185:25 , presentational aggregation, als and retro . I haven't said a lot about
185:32 . Para sequences will return to that I have a whole lecturer that's entirely
185:38 on just that topic. Okay, . Let's see where I am
185:49 And then ultimately the idea is that can look at well, logs and
185:53 to look at the stacking patterns to if their thickening upwards. Perhaps they're
185:59 upwards in this case, here's one finding upwards, it's sticking upwards.
186:03 that might be a transgressive systems These might be Hiestand systems tracks and
186:09 on and so forth. And I give you examples of well, logs
186:13 play around with observing these kinds of patterns. Okay. Mhm. I
186:20 I'm gonna end there. I've got more stuff to say, but there's
186:25 really new in the rest of the that I'll show you. That's probably
186:30 left for next week. I'm going discard that I want to close this
186:42 I'm saying it's a It's about 4 your time. Okay? And I
186:49 we're supposed to go to five. Because we started it, we should
186:52 finishing at 4:30 PM. Please bear me. I know you're tired.
186:57 been a long day. You guys done great paying attention. Um,
187:04 I know what it's like to have sit there for eight hours listening to
187:06 professor mumble and bumble. My voice out pretty well. I really appreciate
187:13 fact that you're listening. I'm sorry didn't have so much interaction today.
187:17 got one more thing to show This will only take a few
187:22 Um but it's, it's your I'm going to give you some homework
187:28 I want you to work on this we're taking our week break here.
187:37 Just give me a sec. Almost . Also make sure you get your
187:45 worth. You're paying good money for to let you and you deserve all
187:50 my time. Even if you're you deserve all of my time.
187:54 , that's not the only one. okay. So the next exercise I
188:14 you to play with is this but you actually have most of the
188:20 to do all of the following We're going to work on this
188:24 I'd like you to work on this the, over the, during the
188:30 Now, Cindy tested positive for Covid , but the line was much lighter
188:37 yesterday. Right now. We're planning leave tomorrow. We should be in
188:42 late monday. Um I will be friends, but if you have
188:47 you know, maybe we can have quick um review of how you're
188:53 Maybe thursday night before we meet on . I'll see if I can just
188:57 , you know, I'll send you zoom meeting what we could do an
189:01 review of of your work if you . You don't have to come.
189:04 you know, it's always good to some feedback during the week. So
189:09 is fundamentally a lap out exercise. main job is to look at this
189:15 start drawing lap outs. Okay. what is this for example? What's
189:25 ? Hello. On lap on lap lap on lap all night. You
189:34 keep going. Okay, what's this ? What's this? Okay, what's
189:45 something else. Okay, what's this ? Yeah, what's this develop?
189:58 this? Good luck. What is that's on lap correct. Tricky
190:12 What's this? That's an incised Valley ? The film is doing that that's
190:19 lap that's on lap as well, . Now, what about this?
190:26 up what kind deposition or truncation? exactly right about here is a deposition
190:40 . Okay. What's this? Good . Okay. You see you're getting
190:44 hang of it right? Here's a one. Uh huh And and there's
190:49 lap out here, there's there's lap there, there's some pretty some long
190:56 outs here. So don't miss these ones. Okay, what is
191:03 That's a tricky one about. so you got lower surface terminating against
191:10 upper surface. So what's that? lower surface terminated against an upper surface
191:28 . That sounds like it is is truncation or deposition? The opposition?
191:34 Probably truncation elin this sense. That's probably slope failure. Okay,
191:41 the exercise. Okay, now what gonna do? So the first thing
191:46 to try is to don't miss You know, there's there's lap outs
191:52 , you know, there's all you ? And then what you're gonna do
191:54 anytime you get a laptop boundary, ? Going to stop drawing surfaces.
192:03 you're going to draw a red surface below your incised valleys and below your
192:14 lap surfaces and then below the On lapping fans here. Okay,
192:20 own lap. Then you're gonna draw blue surface on top of the low
192:30 . And that's below all these down here. And uh there's a down
192:38 surface here, you keep that below down lap surface, on top of
192:41 valley. Okay, continuing on then gonna take the green line and you're
192:53 draw it. And so here you see there is a back step in
192:57 additional unit here. There it is . That's the maximum, that's the
193:02 cutting surface. And then you're going end your project coloring in. Hello
193:28 system tracked and you know, separate submarine fan Incised valley. Then you've
193:42 a color, you're transgressive systems tracked blue and then you're gonna color your
193:52 systems tracked in green, which is thing here. Then you've got your
194:07 sequence boundary and of course I've done so many times. Uh we've got
194:24 top of that low stand there. mean size valley and then you're going
194:30 go into the next you transgress the tracked. So eventually you're gonna you're
194:42 have a series of sequences or systems and sequences defined and key surfaces.
194:50 . And there are 1, 3, 4 five sequences on this
194:57 section. Okay, so that's the . Okay, so that's your major
195:05 exercise um that you should work I'm also going to ask you attempt
195:15 one. I already, I already you this in the lecture. Um
195:20 play around with identifying the on laps lap outs and sequences in that
195:26 And I think that will be enough for of the week. Okay.
195:32 what I'd like to do when we on friday in person. God willing
195:37 make it to texas this will review life and exercise. Um and you
195:44 , maybe try to do that thursday possible. If not, we'll just
195:47 it friday morning. No big I'll also have a look at the
195:51 exercise and see how you get along that? Um, and I think
195:54 got the due dates for all those you know, we're going to start
195:59 the exercise work as I make my from online to in person. That
196:07 right now. Oh, I'm I did. So I made some
196:11 to my exercise one and I was if I could share my screen?
196:17 . You can, yeah. mm hmm. Yeah, that's much
196:27 . So just make sure you put shoes, um, lines on the
196:30 younger units. Okay. Yeah. one thing, um, yeah,
196:37 sure you put your shoes on lines put the little faces in.
196:40 Yes, sir. Now, I'm gonna give you guys some advice
196:45 Okay. Why don't you just think this? I've never told this to
196:51 before. No, but this exercise always look a little funky. What
196:56 the vertical scale on this? 1, 2, 1.
197:04 wait, hold on, wait, , what's the vertical scale roughly?
197:14 many meters on the vertical scale to ships? Continue states About 100 m
197:24 . Do you think the horizontal scale ? I didn't give you one,
197:29 guess what? It could be. supposed to be an entire shelf slope
197:35 . Right? So what do you ? 50,000 1 : 50,000?
197:41 we don't usually express Cross sectional scales way. But let's say the horizontal
197:46 is 100 km right. What's the exaggeration on this cross section? Just
197:54 , you know part of the reason this drama is a little strange because
197:57 got enormous vertical exaggeration. Right? is why it sort of looks a
198:02 bit weird. If you compress this to a true vertical scale, it
198:06 look much more reasonable. Okay? sir. Other than that, you've
198:11 the basic idea, right? The thing that I would advise you is
198:16 your younger units, you don't have shelf tail. So you know,
198:20 you can draw that, you you sort of show the curve which
198:26 the sand. But yeah, I you do draw the tail and some
198:29 you definitely have the basic idea. just keep at it. Yes.
198:37 other questions from anybody else in terms this exercise? But Dennis is gonna
198:42 the hang of it. No, guys are free to work among yourselves
198:48 I'm away and please anytime send me email a text, just say I'm
198:53 . Can you help me? I could get me on the road tomorrow
198:56 monday. So I won't be very . Depending on internet on the
199:01 The plan is to get into I we're going to head to Austin probably
199:04 there later on on monday night. know, I'll be hanging with friends
199:09 Tuesday uh, and Wednesday? Probably Houston on thursday, But by all
199:15 , you know, text me if got a burning question about the exercises
199:19 please do some work on them so we can do some feedback on
199:23 Okay, friday. We'll look at exercises. I'll give you some more
199:28 and we'll move forward. Okay. guys have a great rest of your
199:34 . Hopefully it wasn't too painful during online weekend. My voice is feeling
199:40 . I think my coffin is more fact that I talked for way too
199:43 today. Right? So, I'm going to go have a beer
199:47 my wife and you guys do whatever is you do on your on your
199:52 . Okay? Alright. We'll see . Thank you. Have a safe
5999:59
-
+