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GEOL7323 Borehole Geophysics - Day5 03-03-2023-Part2
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00:00 To answer it. Did you I'm , can you repeat that? Um
00:07 did, how did you make a of this? What did you end
00:10 doing? Oh, I just took screenshot. It was my camera
00:14 Oh, it is off. Um just took a screenshot and send it
00:18 my ipad and then did it that and then I can just send it
00:22 you as a PDF? Ok, , great. That'd be good.
00:28 So please do that and then um got one more little one here for
00:35 just to slam dunk this. ok. Yeah, the song.
00:47 . Let me screenshot this to Yeah. Mhm. Ok. Doctor
07:21 . I sent both. Ok. . Ok. Uh You, so
07:33 let me just check you, you those guys to me? Yes,
07:37 just sent them. Ok, let have a quick boo I'll see if
07:43 got them. Um ok, I , I got the first one.
08:17 . Did, did you send them or were they? Yes,
08:20 they're separate. Ok, I just the second one. Ok, so
08:31 got the first one. Uh I received the second one yet.
08:46 bye. Trust it's on its Uh, let me double check.
09:02 . Yeah, it'll be labeled, , exercise two too good. I
09:12 having a brain part with Archie. , we'll see. Well,
09:18 uh, let's have a look. , we're gonna, we'll, we'll
09:22 them up right now just while it's fresh in our brains. Um,
09:26 haven't received the second one yet. let's, let's go to the first
09:33 . Ok. Ok. That's So let's, let's step through
09:57 Um So here's a, a kind a, a reduced set of logs
10:03 um that are really a rep This isn't, this is um looking
10:11 the logs after the fact. So of the, they're simplified a little
10:16 . So we go through and just a scan at the whole area.
10:22 what you would do is just do partially done is go look at the
10:26 of interest and you can see that uh some pretty, pretty definitive character
10:31 in all the different logs. They're showing some nice excursions and some nice
10:37 . So you can see that the A unit is sort of above
10:41 would guess the area of interest. that's uh and then we go into
10:48 which is showing some excursions that we've kind of a thicker unit C and
10:52 a huge unit D E F as by the uh gamma especially. And
10:59 we go beneath the area of G, I don't know why I
11:03 B E F G. I wanted D E F. I don't know
11:06 I put G instead of D Sorry, here's number one.
11:12 Well, well, uh I'll, have a close look at what you
11:17 done after. Well, we'll just through this and you can, you
11:19 kind of see, you can um as you see fit here. Um
11:25 which intervals? We, we said was the sands shell section. So
11:30 intervals are sandstones? Oh, I B so b Yeah. Um And
11:41 I wasn't sure about d just because kind of like there's the kind of
11:47 that slow slope. Um but I put E N F, OK.
11:55 , um it's, it's a trending and we talked about that a little
12:03 that in a sense you could have something like um uh channel and the
12:11 might be shifting. We just drove through it as you know, from
12:15 graphic concepts, the, as the shifts, you're in a sense,
12:20 going from a sandy area to a area as this channel shifts we're just
12:25 through. So what we see, do see in the top which you're
12:29 pointing out that um That around 80 . Yeah, this is, this
12:38 what our Strat for friends would probably a finding upward sequence. In other
12:44 , it's getting more shay. And could be because again, this channel
12:51 whatever it is is shifting and then lucky through time and then shifted.
12:56 we're going from the sand might still over here. But now we,
13:00 the channel shifted, it's getting more or it could be that this particular
13:07 , the um the tectonics are depositing and more clay rich materials. So
13:17 would say in general, we would this probably a block and where that's
13:22 to be um emphasized. So D F is probably a block. Uh
13:29 it is changing. It's obviously getting shay as you go to the
13:35 However, it's not completely shay because see that it's got um some,
13:43 porosity. Mhm So, but we'll get there. So um uh
13:49 would say B D E F but right, D is a transitional
13:58 OK. So D is uh and could calculate it if we went over
14:04 if, let me just see if can get my little uh um
14:16 uh I'll try to get my Are going. OK. There we
14:41 . So we're looking at this whole . It, it looks like to
14:46 primarily one kind of unit, but right up here, it's changing.
14:51 if we were to pick our sand and here the gamma, we've got
14:54 from 20 to 100. So if pick our sand line, it might
14:58 this is beautiful sand might be, , say 30 20 here and 100
15:08 . So the pure sand line would 30. So we call that 100%
15:14 and then the pure shale line is 80. So there's 50 units and
15:22 the top were, we're probably something we were a little bit screwed.
15:30 not right at full shale here, we're about a third the way
15:36 So up here, that number is there's 20, there's 40, it's
15:42 around 45 And we, so it's . So that's something like about 30%
15:51 . It's still about 70% sand. it's definitely getting shali but I would
15:58 probably call it a sand. This is for instruction, not grading
16:06 uh I know, I, I know why I quit g because I
16:09 it's d so I don't know, don't know what happened there.
16:13 That was a, that was a thing. So, um, so
16:17 going down and so I'm gonna say just on the basis and the other
16:20 is that obviously the S P we said not shale, that's that
16:24 . And then when we look at whole mask, we're seeing that that
16:27 uh you know, it's a hydrocarbon on top of a water or a
16:31 . So that's kind of our classic saturated sound. So then what kind
16:40 gas flus like b well, what you thinking b I was thinking b
16:47 of the resistivity. Um I was that it's brine, it's Brian.
16:53 low resistivity. The uh the pros ran pros agree. That's our slam
17:01 for bright low resistivity agreement here. much change in the Sonic. And
17:09 got all the other reasons to hold . So it's Brine and D I
17:17 . Yeah, this is just a crossover. So this is our classic
17:23 cast and E down here, I E and F being Brian. So
17:30 are, that's our, that's our I really go to conclusion here.
17:38 a little bit of stuff happening in that but we know it's low
17:45 Both units are low resistivity. So , we just can't make that
17:50 we can't make that into oil. then these guys agree. The prologue
17:56 . So we're inclined to say that's saturated uh that's a brain saturated
18:04 The Sonic Log does show a couple interesting things. So it's, it's
18:14 . There's a little, little bit gas in there. Mhm But maybe
18:21 little bit because you can see the change is just a little, little
18:25 . So there might be just a . So we can see there's a
18:28 , little bit of a crossover But um so I don't know,
18:32 there might be uh actually we could this, we could calculate um just
18:39 that very simple Archie's Law. We calculate this value over this value and
18:45 resistivity and probably find that there's a or two of gas in there.
18:52 just that little bit of gas really down the velocity. Mhm.
19:00 there might be just a teeny bit , uh, for peta physicals
19:05 yes, we could, we could it and find that there's a little
19:07 of gas in there. Um, economic interest, that's not gonna be
19:12 interesting because we just, We're probably interested in 98% brine. OK.
19:22 we got that one. Um If could choose and perforate one of the
19:26 , which, which one do you the most d uh definitely d that's
19:30 baby. Um Then, so that's gonna be our main pay,
19:34 pay zone. And then here's Archie's that says if we can find a
19:42 that we're gonna assume is one mythology sand. In this case, we're
19:47 assume that this is one mythology, we can take that 100% saturated,
19:52 is the bottom part over the And that's gonna give us our saturation
19:56 water. So if we take which is from our resistivity scale about
20:08 English or yeah, .25 or And then this guy is way up
20:20 I did 12 because it's in Uh yeah, we could take
20:26 So that's, that's optimistic. So say something like .3 over 12
20:35 then the square root of that So that's gonna be like 16%.
20:50 . So say somewhere around uh Mhm Uh so 16% brine. And
21:04 so our hydrocarbon is 84, around . So it's good that one wrong
21:11 I couldn't remember. I put 0.1 whatever reason because I couldn't remember like
21:17 the R R knot was. Is just like when the log starts,
21:22 , I, that's the one I a brain part on. I couldn't
21:24 what the R knot was. But I remember it's gonna be like where
21:28 line is. OK. Yeah. knot is 100% saturation. And so
21:34 interpretation here is that again, this unit is sandy and we're assuming that
21:42 the bottom according to our logs That 100% saturated and that 100% saturation has
21:49 resistivity value of um .28 or say , somewhere around there. So that's
22:01 or not. OK. And then come up here and yes, that
22:12 10. And um You know, could maybe take 12 That gives us
22:34 . So um the saturation of water 16%. Hydrocarbon is 84%. But
22:45 to make sure that we want to sure that you understand this. So
22:48 the, the, the picture here D E F is more or less
22:58 sand unit, the bottom part is with brine E and F for sides
23:10 the brine. And we said, we want to get really detailed,
23:16 can see that E might have a gas in it because if I look
23:20 the, the neutron density overlay, bang on at the bottom. So
23:25 telling me that's probably a perfectly sand with 100% brine right there. So
23:33 is, looks to be perfectly 100% saturated. Its resistivity is very
23:40 Uh We know that it's porous and and everything from our S P and
23:44 gaming. So that is our 100% sand. Now, we look to
23:52 out what's the resistivity of that 100% saturated sand? And we've gone
23:57 We've said it's around point 25. , I'm coming up here. We've
24:07 all this looks like it's still Brian I'm not getting very much resistivity.
24:17 that's just for fun. Say we see uh a Sonic log drop.
24:24 this, see this Sonic log gets lot slower. Plus we see there's
24:29 little, little, little shift or over here. So that suggests to
24:36 that there might be a little bit gas in there. But why don't
24:40 just try this? I haven't done before. Let's just try it.
24:44 say we had .25 there. what's the resistivity above here? An
24:51 um about Maybe like .3 eight. , it's getting less because this,
25:02 line is .4. So I'm gonna say .35 or something. OK.
25:09 we have .25, divided by What do you get for a number
25:23 ? So if we're really pushing this little bit, What's the uh saturated
25:29 ? I've got 100% here, partial here, like maybe .33 or
25:39 And if I use my little what's the, what's the saturation?
25:48 So, so what, what that gonna be? Zero point You said
25:57 over 35. Well, we're using 100% saturated number. What did you
26:04 before for that? 0.25. Yeah then divide that by the 35.
26:14 , 35. So 0.25 divided by three And then take the square root
26:26 that. So 84.5. So we point uh .25 over .35 Uh zero
26:47 yeah, 0.25 divided by 0.35 14. Take the square root of
26:58 . Yep, 84.5. What? What uh that's gonna be the,
27:05 brine. So then 100 -84.5. 15.5% Hydrocarbon. Yeah. Well,
27:16 know what, when we got picky this um there's some gas in
27:23 Mhm. So there's 15% gas. that, that makes sense to us
27:33 again, there's very little kick on resistivity. This kind of shows us
27:38 you do have to be picky. didn't see very much kick in the
27:42 . Right. Mhm. We we see a little bit on the
27:49 crossover. The blue is just a bit off the red, right?
27:55 we see a fair amount on on the Sonic log. it gets
28:00 , quite a bit slower. So is a pretty strong indicator that there's
28:05 gas saturation here. And if we back to your um fluid substitution
28:15 I'm sure you would find that if put 15% gas in, in the
28:23 , that it drops the velocity a . So that's interesting. But then
28:31 go back up to the uh D this is just the full on
28:36 So we're, we're trending up a bit. We've got a little bit
28:39 gas in here and then boom, just flat give it. What
28:44 what was our calculation? 80 84% up here, 85% gas up
28:52 Uh the bucket. It's interesting. sonic log doesn't care that much.
28:56 put 15% and it does certain amount put in another 70% gas. It
29:02 change this very much. It certainly all the other logs. Well,
29:07 the other ones, but it doesn't the velocity that much. That's why
29:11 hard in the Gulf of Mexico to fizz gas, which is uneconomic from
29:18 really beautiful Boomer gas, which is using P wave data load.
29:25 So we've been through that a little now. Uh the shale volume in
29:31 B. So we for the shale , we've set our sand line,
29:44 . Mhm. Which is very right. That here, Which is
29:54 around 30. And if I come to B and I took an average
30:00 B what would the average gamma be B? Um So when I first
30:07 it, I used the S P and I just redid it using the
30:10 log. Um So I did Um Just because because that's 20 and
30:21 that's 40. Yeah, it's So I did like around 35 and
30:25 I did -30 and then I did . So I got 10%.
30:33 I would, I would say somewhere that I would, so we
30:36 we set our Pure Sand line at , then we come up here.
30:45 you could pick this differently but I , we're averaging, I would just
30:48 what 40, OK. And you pick this differently. I'd say our
30:57 shale is around 60. OK? , our pure sale is around 80
31:03 . So really we had from 30 80. So we had 50
31:07 Mhm 50 divisions between sand and And then I said there was uh
31:13 like 10 divisions, So 10/50 would 20% shale. OK. So the
31:24 thing here is to, to know concept, Let's do another one.
31:32 once again, we're gonna set the line and around 30 according to our
31:36 , gamb is going for 20 to . So if we Set our sand
31:42 , say around 30 And then our line, we're gonna set at say
31:52 . So we've got 50 units to with. Why don't you do another
31:56 ? Tell me at the top of D unit like right up here.
32:01 , what's the because we talked about , what's the shali is there?
32:06 We did that calculation um did not we said it was gonna be like
32:26 a third of The Sandstone. So averaged that. Um so that's a
32:37 , 40. So we could average at about good. So could we
33:00 that maybe around 40? What? ? Which 40? No, I'm
33:09 like in, in general. So set up the equation. So
33:16 I would, I would just say you, what you said, we
33:20 that the sand line was gonna be uh a gamma value of 30.
33:25 said the shale line was at Mhm Then what's your pick here?
33:30 value is your pick here? because like averages between like 60 to is
33:39 like 30? Let's take below the lines because the green line were saying
33:44 were saying that this is a unit we're saying that that the D unit
33:48 really below that green line. So then like Let's see,
33:57 so 45-25. So like 30 40 35. Well, what's the
34:11 right here? Can you see my ? Yeah, so that would that's
34:14 30 is it, are you in middle of the 20 and 40 or
34:19 you on the 40? So here's our, here's our gamma ray scale
34:24 20 to 100. Mhm. So with that line right there is
34:31 Yeah, this line right here is . Yeah. So this these values
34:37 about 50 Yeah, - 50. Given that these values are 45,
34:47 say what's the percentage stand right About 50%? Well, I would
35:02 cal you you better write it down the calculation. Oh I thought you
35:06 just like me was like looking at . OK. So if I use
35:12 so it'd be 50 -30. So 22/5 So 40%. Yeah.
35:29 I'm sorry I thought you asked me what the first like what the value
35:33 were using to plug into the I don't know like OK.
35:37 that's OK. So we're just trying figure out more or less what's the
35:42 is just doing some mental aerobics with or some just picking this stuff so
35:45 you get secure with it. for sure. And uh so at
35:50 talk, we talked about that Is that a pure sand?
35:54 it's not. It's actually, it's about 40% shale. And so that's
35:59 dirty sand maybe. And, but the other hand, we uh our
36:05 logs tell us it's still pretty So, so once again,
36:10 the uh the important thing here is know this, just this general
36:17 we're gonna set us a sand a shale line and then whatever excursion
36:21 between those two, that's what we're call our percent shale or percent
36:25 And so that's the shale volume uh . So just to hammer it at
36:44 depth right here with my pointer, the, what's the, and this
36:49 in unit G, what's the percentage there person in sand will be um
37:00 see. So that line is 60, 60%. Yeah.
37:18 So that case 60%. So we're kind of picking this as a
37:23 . But is that a pure shall no, it's getting that way,
37:30 it's not there yet. So you see that the environment is kind of
37:34 here, whatever was happening, tectonic around there, it's starting to get
37:41 and more curse. So it looks it's raining a bunch more and
37:44 it's getting sandier then all of a something major has happened, you
37:49 a river cut through or, or was a completely different event where all
37:54 a sudden we've got all this sand it was getting sandier. So something
37:58 happening. Mhm OK. So now next question is that this just takes
38:08 little bit longer. But the we wily time average uh equation said that
38:17 slowness of the rock was equal to porosity times the fluid slowness plus one
38:24 the porosity times the matrix slowness. that was the, and so we
38:31 just plug, you know, normally have a table with the, the
38:36 of the, the fluid. And know that that's brine. So what's
38:41 , what's the density of brine Uh was that 2.1? So the
38:50 just of the brine, I'm kind jumping here but the density of brine
38:56 the fluid. Oh It's um I , I don't remember what's the density
39:09 water? 11 and then brine is or more dense than water. It's
39:20 . Yeah. So in fact, you, 02.28, yes, it's
39:33 that much more dense. So it's , it's still water. Brian's pretty
39:37 water. OK. So you're thinking is one 1.0 g per C
39:46 So that's just standard water. Brine a bunch of salt dissolved in
39:50 So it's just a little bit So it's 1.1 g per C
39:54 oh, ok. So, brine still water basically. But it's just
40:00 salty water And it's about 10% So, how you can remember
40:13 Maybe. Have you ever, have you swam in the ocean?
40:18 float better or worse in the ocean in a freshwater pool? You float
40:23 . You float better. Why is ? Because of the density?
40:28 it's, it's a little bit, a little bit denser and it's not
40:31 much denser. It's only a few denser. But if you go to
40:35 Dead Sea in Jordan, the, , that site, the biblical
40:42 you can go to the Dead Sea it's extremely salty because it's below sea
40:47 . Everything drains into it. It very, very salty and it's really
40:50 . So, the water evaporates and can float in the dead sea and
40:53 float and you can read a book there. It's so dense and you're
40:59 buoyant because we're kind of mostly Our body. So, you float
41:05 it. So, bride itself is 10% more dense. And so that
41:10 floats everything. Mhm. So, , you can kind of think of
41:15 as an iceberg in water that fresh floats on saltwater and, and it
41:27 . Ok. So that's, that's of, um, but in any
41:34 , the, uh, so uh, the porosity that we determined
41:39 the sonic is, we used Wiley's . This is a very simple model
41:44 the uh the transit time through the is equal to the porosity times the
41:48 velocity plus the one minus the porosity the matrix. Likewise, with the
41:55 um with the density log, we the blic density is the porosity times
42:01 fluid plus one minus the porosity times matrix density. So the equation has
42:05 same form one using transit times or and the other using density.
42:15 and then we just manipulate those equations define porosity from those obser observations.
42:23 that's, that's that guy. Any there or no? OK. Um
42:35 then just to heap more grief on , we did another one. The
42:44 is that you're so sick of this you can just look at it and
42:46 know, immediately what the answer That's the goal. So we look
42:51 this guy and it's got the same again. So what do, what
42:59 you recognize here in general? Um the, the low gamma through that
43:07 . But then we have the oh I'm so frustrated with myself because
43:18 I didn't do well. Um you that low resistivity right there. So
43:23 that would be Brian sitting on top um Well, no, I did
43:36 it right. Oh My God. That's high resistivity right there.
43:39 yeah. No, that's oil sitting top of something, Brian.
43:47 So again, you don't have to this all at once you, you
43:51 be really, really simple minded and step through this stuff, especially at
43:58 , you know, you don't, don't start skiing double black diamonds with
44:01 on a 45 degree slope first and you, you want to pick your
44:05 through those moguls and uh and not off them too hard. So
44:10 we're looking through here. First of , the overall character is, there's
44:14 much happening too much as far as S P is concerned and the gamma
44:21 a little bit more chatter, but idea. So we're thinking of an
44:26 unit that's kind of homogeneous, lower . And then I've got this anomaly
44:32 the middle and we're always thinking there a reason these guys spent money to
44:36 this stuff. Mhm So they're looking some kind of anomaly. So we
44:42 that we've got a clean interval in . It's also permeable and I come
44:47 and I think, wow, there's classic signature in the resistivity, high
44:51 over low resistivity. So that tells immediately hydrocarbon over brine probably. Now
44:59 gonna go through and look at and think, oh and there's a little
45:03 lower velocities, the sonic log is slower or longer and then my neutron
45:14 my density are overlying pretty closely. that tells me that this bottom part
45:27 probably Briny. Mhm. The top is hydrocarbon. I don't really see
45:41 crossover here. So I exclusion it be oil. Mhm. Uh,
45:56 , the Sonic log again, tells that the velocity is getting a bit
46:01 . So that's, that's a little interesting. And it probably, again
46:08 us that it's a slightly more complicated . It's oil but yet,
46:17 it probably has a little bit of in it and the, um,
46:22 oil is affecting the rock a little differently than, than brine. And
46:27 , we kind of expect that again, um, oil has a
46:34 density. What was the density of ? Again? Less than water?
46:42 than water? Uh, certainly, less than Brian. It, like
46:50 or something. Perfect. You got . That's, that's our 32 degree
46:57 oil which we know and love and even when you don't think about
47:03 you're starting to get the numbers, is good because that's what you
47:08 that all of a sudden that number to you and you don't know where
47:10 came from, but it came to . So that's, that's what we
47:14 . I just realized because when we the results at work, like all
47:18 our S R OS and like the residual oil and the sulfur crude
47:22 it's like, I was like, a second, all of those are
47:24 in the eighth. I was like . Yeah. Well, and
47:29 that's bang on. That's why, , that's great to attach something from
47:34 else that, you know, and , first of all is great because
47:40 the basis of intelligence, intelligence is wiring in different stuff. It's the
47:45 in your brain. That's big part it. And then, uh And
47:50 you're confident of that because you maybe work you've seen that number about 1000
47:54 and you say, look at, know that this number is .86.
48:01 , oh, that carries over to because that's the density that we're interested
48:09 . Now again, that's, that's of a nice, like we've talked
48:11 oil is very, but that's, a nice middle value of oil.
48:16 very close to West Texas intermediate. that's all good. OK. So
48:28 I think you're getting the hang of of these logs and there, there's
48:31 lot to um there are a lot different blogs, but I would say
48:40 in my opinion, I think in ways for reservoirs log is the most
48:47 thing to understand because they, there's , gives us seismic measurements and it
48:55 us an area and everything, which all great. We love it,
48:59 it doesn't tell you everything about the . It gives you a geometry,
49:03 a Strat gray. But with you've got all these different measurements.
49:08 got nuclear measurements, electrical measurements, measurements. Um So we've got so
49:17 more measurements to tell us about the and we're getting right at the rock
49:23 pretty directly. So I think it's important to understand these log responses because
49:32 really tell us all the different things the, um, about the rock
49:35 its fluids. Great. Ok. questions about some of the,
49:56 any, anything about the logs? , no, not right now.
50:04 , let's, let's take a quick . Stephanie and then, uh,
50:09 back. It's, uh, 2 . Let's see, uh, at
50:14 . Ok. All right. See shortly. Ok, great. Welcome
50:22 here. We be good, Um, ok, we both got
50:34 , our shirts on. So that's , yeah, I was thinking
50:41 we could have gotten to the university but uh we hadn't really planned
50:44 So, uh I didn't know whether were able to get down or
50:50 but I'm glad we, because when messaged me, I was leaving work
50:56 I was like, oh my I'm gonna have to go all the
50:58 home, change my pants and then to the university because I didn't know
51:03 was just gonna head up there and he messaged me. I was
51:05 oh, thank goodness because that was be the craziest drive of my
51:08 Ok. Yeah. Yeah, we , we don't really want to have
51:12 do that. I do it periodically and I think, oh man,
51:17 know, I was trying to get to Katie or something for a meeting
51:21 you have to go mental and I hate that is bad and you
51:26 want to do that unless you have . Um good. Well,
51:30 let's just quickly review this to make we have this uh this concept because
51:34 moving now into the seismic. And synthetic seismo gram is the um is
51:43 intermediary. It's the link between our properties and everything we understand about core
51:48 well logs and it's our link from geology to the seismic response. So
51:58 , the uh the measurements, the that we are thinking about this is
52:02 most of the exploration in the oil is really done with seismic. And
52:11 we have to understand what is the telling us and how do I get
52:16 to the rocks? Because ultimately, produced is a fluid from a rock
52:20 depth. And that's not exactly what seismic tells us. And so we
52:23 to understand how to put this stuff . So we just on the slide
52:28 , you can see the uh from to seismology. Um We imagine that
52:33 got are uh just a cross section the schematic diagram of, of the
52:41 of the earth. And we've drilled well, what's the symbol again?
52:48 you remember what that symbol is? doesn't that mean like open or
53:01 Yeah, more or less it means dry hole. It means that you
53:05 looking, you were looking for gas oil, you didn't find anything.
53:09 so yeah, this is, this open your bank account and pay for
53:17 . So yeah, it, it's open in a sense, it's
53:20 dry hole. So that's very But um this is just uh
53:26 Fortunately. So if we look at well log though, we could imagine
53:31 , that there are a bunch of well logs. And if we multiply
53:35 , so the sonic log velocity and density together we get an impedance
53:40 And then the change in the impedance as we go deeper from point to
53:44 . So can we imagine that each of these is a value? And
53:51 the reflectivity is the change in the as we go deeper. So that's
53:56 we defined it. It's the fractional across an interface. So explicitly,
54:13 imagine, and we imagine that every from a log defines a little
54:19 So the log values are at say foot, every foot has a
54:25 And we imagine that that's a Now a bunch of those layers might
54:29 the same rock because we just output log at whatever the log started and
54:34 . So, but each one of one of those one ft layers or
54:40 ft points in the on the log be significant. So we remember that
54:46 the logs are output at around one interval. That's that's the data point
54:52 . On our logs and we're going compute the impedance at every one of
54:58 log points. So something like every foot is going to give us
55:03 impedance. Now, I've got an log and if I look down that's
55:10 , I could say, well, the change between P I and P
55:14 plus one or the next depths And then just look at the difference
55:20 those properties as I go deeper, difference of in pens I plus one
55:30 I, that's just the change over sum. So this is the fractional
55:34 change, it's really half the fractional change. So that in very simple
55:40 , the reflectivity is a derivative, derivative of the impedance or it's just
55:47 the, how is the impedance changing I go down the well? And
55:51 the reflectivity and that's the amount of that's gonna get bounced back by uh
55:59 vibration that goes into the earth. if I had, if I had
56:07 pulse that was very, very high broadband, actually the seism coming back
56:13 look like this, but I can't a powerful enough impulse, high enough
56:24 because the earth absorbs all that energy like if you scream happily at someone
56:34 sound energy gets absorbed. So maybe the room, they can certainly hear
56:39 , but in uh spring, they can't hear you. Although believe it
56:48 not, there are screaming contests to who can be heard at the biggest
56:53 and I forget what the numbers but some people can scream and be
56:58 about a mile away. Oh my . So uh we know that we
57:09 transmit those high frequencies. And so so we can only transmit kind of
57:13 lower frequency that will propagate through the and not attenuate. So because of
57:18 effectively, when I put in a frequency on the surface that chirp or
57:24 character is reflected by every one of . And that's where we get the
57:30 result that every one of those reflection sends back the input signal, but
57:40 does it. So we have to them all together and that gives us
57:42 seismic tree. Right? Yes. . So remember that now what it
57:54 like uh going to a real So suppose I multiply density times
57:59 I get this say uh impedance And then for every one of these
58:06 points and layers, I take the between the above and the below scale
58:11 , that gives me the reflectivity. is actually just a, it's just
58:18 a well log we've constructed a new log. This is a reflectivity well
58:24 and, and that's what it it actually is a, just like
58:27 impedance log is a constructed log reflecting rock properties. The difference in the
58:35 is a a real well log. reflectivity, but that's a well,
58:40 to make it relevant to seismic. have to say, well, what
58:45 seismic does is puts a band limited into the earth. You've told me
58:49 principle, every layer how it could . And that's great. Now I
58:54 in this guy and this is what does reflect when I sum that all
59:00 . So this is what I And the important thing is that when
59:04 got this seismic and sometimes I can my little pointers. Sometimes I
59:16 we see the seismic and blue on right. And now each one of
59:20 wiggles, we can take it back the left and see what caused that
59:27 . Now, it's hard because the wiggle is an average. It's a
59:32 , it's the result of summing and the activity. So if there's a
59:39 happening, the activity, it kind gets jumbled up and looks uh maybe
59:44 bit different in the seismic and that's way it is. That's our seismic
59:48 . That's what we get. So we more um realistically what people in
60:00 industry are all doing is it's usually in two ways. There's a well
60:09 been drilled someplace usually on the basis two D or 3D seismic. You
60:15 in, you drilled well. And that's all good. And then we've
60:20 all the log analysis, all the physics, all the horizon from the
60:25 here. So say these uh logs the right? You, you can't
60:34 my pointer, can you? I can see your mouse.
60:38 you can. Oh OK. good, good. Um OK.
60:44 you can see that the logs in and the right, we've um there's
60:50 of character in here. We multiplied density times the velocity to get the
60:57 and then took the difference of the created a reflectivity and then convolved out
61:03 the wavelet which was the seismic um , either the vibe or dynamite.
61:10 looks like this. And then we our synthetic seism gram in blue.
61:18 then I've gotten real seismic in And so our interpreter job is to
61:27 take that seismic section and compare it the synthetic and then annotate the seismic
61:36 with what those wiggles mean. And done. So you can see some
61:44 these uh horizons. So the horizons picked on the well logs and from
61:51 driller. So we can see there's funny things like B F S which
61:56 mean something bad, but it actually the base of fish scales. So
62:04 fish scale is uh is a marine and still got fishes in it.
62:11 you can actually see the uh the fossils in it. So that's just
62:15 shale there. And then you go , you can see that there.
62:18 colony is pick colony sandstone, the sands, those are all just horizon
62:23 in this particular area. OK. you can see those going from the
62:30 extending right through. We've got a correlation with the blue synthetic seism gram
62:37 the red and black real seismic. this is an indication that,
62:43 this stuff almost looks like it Now, there's, there's one thing
62:55 been baked into this, that is immediately obvious but is really important.
63:05 that's that the logs, as we , are measured in depth, we
63:10 in depth. And so they all measured in depth and we've got this
63:14 vertical depth from the surface. So our log deaths. Now, what
63:24 really done is we've converted those depths time and we talked about this very
63:31 . And why are we doing that ? Because the seismic section is not
63:35 in time of the echoes. So um as we know, we,
63:52 blasted, we whack the surface and the energy went down and it was
63:56 off all these reflection layers and then sampled it, we listened in
64:01 So the reflections, the echoes are time. So our whole seismic section
64:05 went around, we did that every we got this big volume or
64:09 And that picture is also is of in time. So that's the black
64:15 and it's, it's native value. recorded value is in time. And
64:22 , and it's two way time because takes energy, you've gotta go from
64:26 surface down to the horizon and So that's what two way timings it
64:31 down to the horizon or down to layer and back. So that's not
64:41 in the raw form. The log not showing that in raw form,
64:46 log is showing properties and depth. we have to really convert the log
64:52 , it squeeze it do whatever we to do to make the log look
64:57 it's in time. So that's really mapping depth into two way type.
65:09 there are, there's the first way we're going to do that. So
65:17 mentioned, we have, we have Sonic log. So the, the
65:22 really important aspect of the sonic log to provide a mapping from depth to
65:32 . So the sonic log is, output in transit time. So we've
65:37 the Sonic log in in depth and go back to one and see if
65:42 can find one someplace. Let's let just try to find a Sonic
66:03 It's in time. How about this ? No, I fixed all these
66:23 uh into velocity. OK. here's, Let's find an easier
66:36 What was the unit on this Oh I, I've made these olive
67:01 . Um Where's one that's in the ? Well, here, here's actually
67:19 . It's just hard to read. uh we've got, we've got our
67:27 log in slowness or delta T. this is, this is just a
67:32 weird again, we've got this in which we know and understand. And
67:36 we've got a measurement of the time a foot, the delta P or
67:43 a meter. So once again, got a measurement of the uh
67:50 at a depth. I know the across that depth because that's what my
67:56 log is output, right? So can imagine if I've got this interval
68:03 I know the time across it, interval, I know the time across
68:07 this interval, then I just sum of those times together. So all
68:13 have to do is take the uh per foot. Here, it takes
68:21 long to go across a foot, microseconds per foot here, it takes
68:24 long to go across that foot, that there. And you can see
68:28 now I get depth and by summing of those microseconds per foot, I
68:33 a time across that interval. So summing the Sonic log, I get
68:41 depth to time map. So uh we can do is let me
69:19 uh I never use, well, very weird. It's kind of offset
69:30 my uh Well, we can imagine um you can imagine that we have
69:39 here. We have time here and I'm going to sum all the
69:49 And so now I've got depth and and I've got a mapping from depth
69:58 time. So let's go back to we were. So that's how we
70:25 it. So, uh in this , let's just kind of see if
70:29 can draw that. We have, have the original. This is,
70:42 is very weird. My pointer is one point and then the line comes
70:45 at another point. Well, we our, our depth on the uh
70:58 are in depth here and then by all the microseconds per foot, I
71:04 from this depth to this time. so I just stretch, using that
71:23 , I just stretch everything to And as it turns out, and
71:40 can calculate this A very standard velocity most sediments is somewhere around 2000
71:51 That's a standard P wave velocity for near near surface. When we get
71:57 the carbonates, we go 45 6000 per second. But in the plastic
72:01 in the shallow section for 1000 m something, we're going to have 2000
72:05 per second. So if the say is down 1000 m And the velocity
72:26 2000 m/s. How long does it for me to get my reflection?
72:36 little pulse at the surface goes 1000 m comes back 1000 m and
72:41 velocity is 2000 m per second. it just be one second?
72:48 OK. So here's a little uh of guide in the near surface,
72:55 generally know velocities are somewhere around So If the reflector is at 1000
73:04 how long does it take a game get my reflection? One second,
73:09 is how many milliseconds point? So many milliseconds in a second? Isn't
73:23 ? 1000? Yeah. So it'd .1. No. Oh, just
73:33 or two. So if I was plotting in the scale, I could
73:37 one second or how many milliseconds in same scale? Just 1000.
73:45 That I was like, I don't how to say this number.
73:48 So 1000 milliseconds by definition is one where we're going is that If I
73:56 a well log and I had a interface at 1000 m depth, then
74:03 where should I see that interface in ? So I've got an interface at
74:10 m depth. I've got a standard surface. If I whack the
74:15 when's the echo gonna come back a ? Yeah, 1000 milliseconds. So
74:22 the quick, here's the quick look that you can amaze all of your
74:27 and petrology and everybody else friends, slaps a section down and it's a
74:32 section in time and it says 1200 and all the engineers on everybody looks
74:36 says, what the hell is And you say, well, it's
74:39 around 1200 m deep. Oh, do you know? I guess we
74:43 need a geophysicist here. Hm. so there's a there's a little mapping
74:51 easy for a standard near surface that time we see in a seismic section
74:58 milliseconds is approximately the depth in So anywhere around here, the velocity
75:18 the near surface around here down on 1000 m is somewhere around 2000 m
75:25 2nd, 7000 ft per second. the sediments around here are something like
75:30 . They're, they're kind of loosely plastic sediments. So if you slap
75:36 section on my desk and I could a reflection at 1000 milliseconds or one
75:43 , I'd immediately tell you that's around m deep because we know that
75:51 the, the geology around here is similar and that um most of it
75:58 somewhat less consolidated plastic. OK. um that's just a little device.
76:16 , if I'm looking through salt or it's carbon in the surface or I'm
76:20 the Middle East or some other all bets are off, the velocity
76:23 different. So if, if I in the Middle East and it was
76:28 carbonate rate to the surface, which about three times as fast then,
76:33 I saw a reflection at one 100 say 1000 milliseconds, one second
76:40 goes three times as fast. It three times as far. So that's
76:43 be at 3000 m, not, 1000 m, but for around
76:49 for most plastic stuff, that's just little thing so that you can do
76:53 fast. Now, if you look the slide here and we're looking at
76:58 near surface, this is a plastic . So the time is in
77:05 So I've got 600 milliseconds. When you guess? How deep do you
77:09 that is approximately at 600 milliseconds? . So 600. So it should
77:19 somewhere around 600 m deep. if we go across, we
77:23 well, it's just over 500 m , but we were in the
77:28 it's not 2000 m deep. And this is not perfectly 2000 m meter
77:34 second, but we got pretty So I said that 600 milliseconds two
77:40 time was approximately 600 m deep. , it's 5 20. So
77:47 I got close now to be Obviously, we're gonna be different.
77:51 just to get you in the game . When somebody puts a picture in
77:54 of you, it's also a way QC yourself. So when I'm looking
78:00 data all the time, I'm trying second guess my opinion and make sure
78:05 got the units right or try to if something's messed up. And so
78:10 is just one of the things that cross check. So once again,
78:17 in this case, we've got our from depth on the right to time
78:23 the left. And now my interpretation shifting all to time. I've converted
78:27 my logs into a uniformly sampled And most geophysicists do their first blush
78:34 interpretation in time because that's the way size my kids and we paid,
78:41 , we paid for all this So we've got to interpret it.
78:46 . And the way we're going to it is first blush through comparing the
78:52 in time. I can just take logs and just compare them. And
78:56 I know what seismic is, I kind of say, well, here's
79:00 positive impedance change that should give rise a positive reflectivity. And I go
79:07 here and sure enough, there's a black positive spike. So after a
79:13 I don't even need the synthetic seism . I can kind of do this
79:16 my mind and say, OK, an impedance increase here. That should
79:21 a a big black spike. there it is or there's an impedance
79:31 here. I expect a trough. if I go across here, the
79:35 area, I see a trophy in . So we're just manipulating these logs
79:44 our mind. But if I want see the true seismic response because it
79:47 will surprise us because when I convolve this stuff, when I low past
79:52 , it, it can look a bit different. So I do that
79:55 then directly compare the blue synthetic to red, which is just a repeat
80:01 one of the black traces. So we go. OK. That makes
80:12 . So now let's, let's think that was kind of a one D
80:17 synthetic seo gram. And that's the thing that everybody is gonna do to
80:21 seismic two D or 3D. But we're gonna look at this a little
80:26 more detail and think of, exactly what causes that seismic response.
80:35 we imagine that we built a velocity density model and then I've set off
80:39 shot in the middle of it. , I'm gonna look at how the
80:41 propagate. And so we can imagine set up a shot and the wave
80:50 to go down into the earth. we could get as complicated as we
81:00 , you know, in this we've just got our simple P wave
81:03 down into the earth and there's also kind of shear wave afterward and there's
81:11 kind of direct wave between them, this is uh in depth and
81:17 So this is just um as you see the wave propagate in the
81:25 we could measure what's the vertical particle or we could measure what's the horizontal
81:32 particle motion inside the earth. when we, if there's an interface
81:38 here, then the P wave is bounce back some of it's gonna
81:46 So here's the P wave bouncing back the interface here is it's propagating,
81:51 transmitted as we would see the vertical and the horizontal motion So once
82:00 we've gone, there's an interface at m depth. So the P wave
82:08 gonna go down. Sugar wave is go down, then it hits it
82:15 wave bounces back and transmits through the wave bounces back and also transmits
82:24 I can look at the vertical motion the horizontal motion. Now, even
82:31 the simple case with uh with the here, the energy has gone
82:36 it's transmitted through, it's reflected that reflects off the surface and comes down
82:42 . And so in pretty short you get a real mass, everything
82:47 shaking, it's a bowl full of and that's true. And so that's
82:54 surface sizer processing tries to disentangle and a picture out of all this
82:59 And unfortunately, the primary reflection, first reflection is the biggest. So
83:07 helps us, these reflections off the are multi paths or multi poles and
83:17 confuse the story. But, but real, so we in surface seismic
83:31 , we're gonna just uh have a of different techniques to get rid of
83:37 . OK. So that's what we is really happening in the earth.
83:40 if I can drill a hole in , I will see these waves pass
83:46 the and that's where we're going because , if we process the surface that's
83:52 surface seismic, but that's a different of your courses. Yeah, if
83:57 put receivers in the well here then a borehole measurement and that's a borehole
84:04 or a vertical seismic profile or an situ seismology. And that's for
84:14 But we can also think of this different way if I had receivers on
84:19 surface. Now I can plot what each of those receivers on the surface
84:27 from that previous wave propagation or that modeling. And now we can see
84:35 the strictly on the surface, there's wave that propagates across the surface.
84:41 we see that here it takes longer get there the farther I go
84:44 that's the direct arrival, there's a , of course, the rail wave
84:49 bound to the surface that's got a elliptical motion. That's this guy coming
84:56 , takes longer to get to further . And then of course, we've
85:00 the reflections coming up different subsurface. we can see that that's that cool
85:07 here and then there's p and there's wave and there's pure sheer. So
85:14 got all these different wave types now in offset and time. OK.
85:25 we've, we've looked at, um looked at different concepts of how the
85:42 are bouncing around and now let's go the well, and we'll start to
86:09 stuff inside the well. So I laughing that this is a friend of
86:18 daughter and she's now in 2nd Year . So this was a while
86:27 So your little one will soon be university, believe it or not
86:33 Yeah, I know. But when look at her this, she's
86:39 I guess, 21 years old and a lot of her own opinions
86:49 So we're looking at, uh, we're, we've talked a little bit
86:54 the logs, we understand the the rock properties. We've also talked
86:58 , about, um, getting a in the surface and the waves propagate
87:04 the, in the surface, the and bounce back. We're gonna move
87:11 uh borehole seismic because we now need tie our well logs to the most
87:18 surface seismic methods which are seismic. we, we were looking at one
87:27 to link the log properties to the that's by a simulation which is good
87:32 synthetic seism grams. You can see they work pretty well. But there
87:37 a lot of aspects that uh need too because the synthetic seism gram is
87:42 real seismic data. And there are lot of assumptions in it. So
87:48 would like to get a real seismic between the rock properties and circum
87:57 And that's what the V S P whole size was used for. And
88:01 are different names BS PB Seismic in , meaning inside seismology. Well,
88:10 Moral geophysics and then a former student mine, uh Sam's son published this
88:18 on borehole seismic BS P in If Utah is there, he could
88:24 read the title are you there? guess. So you when you read
88:33 title in Chinese, yeah, just from Chinese, it's called. So
88:46 the three dimension two component, both math of the V S P master
88:52 its application. Perfect. Thank Thank you. OK, so uh
89:00 , you can see here um uh the name of the method in
89:07 So that's kind of fun. Uh are, there are a number
89:11 of books again on V S Uh This is probably the most recent
89:19 . So there hasn't been anything out about 10 years on V S P
89:25 I'm aware of. But, I would say that this is one
89:30 published a long time ago when I a graduate actually just after grad school
89:36 I was trying to find a copy it because it was published way a
89:40 time ago and I was really happy see that somebody was selling a copy
89:44 something like I think six or Oh, wow. I thought,
89:50 . I like that. Um, , I didn't buy it. I
89:56 somebody else did but I was searching , uh I was searching uh,
90:07 week or two ago to see if can land another copy. And sure
90:11 I did find one. Uh, happy to say that I didn't,
90:19 didn't pay that much for it. , I, I'd, I'd had
90:24 copy or two but I hadn't uh , they got lost or some place
90:29 some move. But here's the basic . Once again that uh with the
90:34 S P we imagine that we've got seismic source, we've got our seismic
90:46 and we shake the earth somehow. now we have a borehole and we're
90:51 put geophones or motion sensors or, distribute acoustic systems or accelerometers or some
90:58 sensing device in the well. so the whole concept. We gotta create
91:05 vibration somehow, a mechanical vibration that's disturb the, the ocean or
91:11 the sediments a little bit. And amount of disruption with um with our
91:16 seismic waves is on the order of micron. It's not very big,
91:20 just a very, very minute vibration the earth and then it's gonna propagate
91:28 the earth and rattle around and, then we're going to detect that motion
91:33 the well with our receiver. we can uh we can do all
91:41 of different geometries and it all looks . They all have different names,
91:47 there's, they're just different ways to the source and receiver and why um
91:55 they're all given a name is because name uh describes something about the
92:01 But it um it also describes uh much it's gonna cost you. So
92:13 can see here that a checks shot , you only put a couple of
92:20 in the well and it's just checking velocity to uh to different depths.
92:40 zero offset means that we're dealing generally a one dimensional material and that the
92:49 is quite close to the well So by zero offset, it's just
92:54 that the source is close to the head. But it also sort of
92:59 that everything is one dimensional that, the earth is flat and that it's
93:05 of like a, it's sort of a well log that everything is vertical
93:10 and one dimensional pretty simple a walk as you can see is when the
93:15 is right above the receiver, uh V S P. The other big
93:19 means that the source is substantially So now we have to take into
93:25 offset effects and you can see the kinds of names With the offset
93:38 We kind of imagine that the world still one D one dimensional. But
93:46 I can make a bit of a away from the bore hole because the
93:49 point is away from the borehole. I start to look at 3D,
93:57 could have shots anywhere. And now gonna be able to reconstruct a three
94:03 , not just a one or a dimensional picture, but actually a 0D
94:09 . And the different geometries once get different names walk around in the
94:13 case, walk away walk above. One that is a little bit different
94:20 the reverse of E S P, means that I put a source in
94:23 well, and I have receivers on surface. So those are all the
94:32 kinds of geometries that we can We have. Um So by walk
94:37 , we imagine that there's sources that going away from or walking away from
94:43 well head. And you could see this can give a, a set
94:49 waves that are simply shown here. now we start to look at what
94:58 we going to record from the So we saw there that we can
95:06 that the, the source is vibrating shaking or impulsing energy is gonna come
95:14 and that's going to hit the borehole our measurements are gonna be made at
95:18 borehole. Likewise, energy is gonna down and hit a reflector and bounce
95:26 and will, will grabbed out of borehole too. Now, for the
95:31 S P, there's something that's pretty . You can see that some of
95:38 waves are captured when they're going down some of these waves are captured when
95:42 going up. So we've got downgoing and we've got upgoing waves and we're
95:53 use both of them. The downgoing are gonna tell us about transmission
95:58 The upgoing waves are gonna tell us reflection properties. So those are both
96:03 to us. So once again, could imagine if depth was increasing this
96:13 and with V S P it's, plotted always in a lot of different
96:19 . So you gotta, gotta put head on the side, stand on
96:23 hands, do all kinds of different to, to understand what's going
96:30 Once again, we have to always at the scales and the units to
96:35 out what is happening. So we've depth going into the earth like
96:39 We imagine that there's been a shot the surface and that energy is going
96:45 the earth. So we imagine the goes into the earth. That's the
97:01 wave. And then at different it's going to hit an interface and
97:08 back to the surface. So energy gone into the earth and bounced
97:14 It's gone into the earth bounced back the earth deeper and bounce back.
97:24 this is basically a shot gather as can imagine that I had receivers all
97:33 way down in the earth and I a shot and this is what each
97:39 would see. OK. So we can model that we can take
97:53 . Now plotted the other way we have a log. And we could
97:59 if I look at the actual we've got actual offset, actual
98:07 a log in depth. I can shooting. And here's my energy that's
98:11 into the earth. So this is propagation in the herb and this is
98:24 we would see. And I'm having little trouble seeing because it's allergy season
98:35 it makes my eyes go crazy. . Today was very, very
98:44 Yeah. Yeah. It's, we're told that it's happening earlier this
98:52 . I, I could have told that a few days ago, for
98:55 . Oh, yeah. Do you some allergies or? No?
99:01 I do. And it's, I really only have seasonal allergies but
99:06 , it's this season so, you know what? I, I
99:10 never had, I never had seasonal um until coming to Houston and,
99:18 it doesn't affect anything with me except eyes and my eyes go crazy different
99:25 . Um Thank God for Zortec Yeah, there we go. So
99:35 but back to this. So when looking at data in depth, if
99:40 had a receiver in depth, this the kind of information I would
99:45 It's taking longer to get in depth we can see in the right.
99:49 that's my direct downgoing wave in depth then it's hitting interfaces and bouncing back
99:55 the surface. So if I had GEO phone right at the surface,
99:59 going to see the direct arrival, primary reflection and a primary reflection.
100:05 this receiving in the surface is our we know and love from surface
100:09 But now we get to see how whole wave field is propagating in the
100:13 and how it's bouncing around. And on the, on the right
100:18 it's just showing what the wave field really look like inside the earth.
100:23 it's propagating all the way down. , but that then of course,
100:32 back, giving us these guys, two different ways to look at and
100:37 to understand what the V S P . Then inside the uh the G
100:48 that we have in the V S typically has a vertical sensor and a
100:53 sensor. And we get, we get the, the different components of
101:01 wa field as measured either in the sensor or the horizontal sensor. And
101:06 got those all the way down the . And you can see that.
101:18 , we're thinking that there's not just compression wave that's going down, there's
101:22 a shear wave that's going down And so we measure that shear wave
101:25 the vertical sensor as well as on horizontal sensor. So we really have
101:34 full V SPS or three because normally have a three component GEO and a
101:40 and two horizontals. So there's at depth we've got a measurement. So
101:45 fact, we've got three shot gathers , horizontal, one and horizontal
101:52 So I've got three data sets for shot good. Let's take a quick
102:01 , Stephanie and then we'll come back finish off for about half an
102:04 So let's just take five and we'll it about four and then come back
102:08 do four V S P Ok, you. All right. See you
102:12 a bit. Ok, great. , we're talking uh about general ideas
102:24 the V S P and the general being, uh, something that
102:29 disturbs or mechanically alters the surface or it. Um, in terms of
102:36 , there are lots of different sources we use. The first one is
102:40 called impulsive and impulsive means that there's one big whack or, or hit
102:46 something like that or explosion. So not uh a continuous shake. It's
102:55 one um disturbance. So impulsive is off uh dynamite. And you can
103:03 the guy here, he's got um I probably five lbs of dynamite.
103:11 these, these guys get screwed together each and then you put a little
103:15 cap in it. He's got his cap. And so that is an
103:20 sources. The, the standard shot to be £5 at 50 ft,
103:26 is an awful lot of dynamite. , uh smaller charges are often used
103:32 they're just less dangerous and uh less . And then there's a compressed air
103:39 that could just accelerate a plate. Another one that's uh this was compressed
103:45 that would um that would put drive , drive a plate down. So
103:55 are all impulsive sources that are used the seismic world. Dynamite is still
104:00 quite a bit in, in various . Uh It's a great source
104:04 it just produces one nice big And so that's easy to interpret.
104:08 so uh dynamite is pretty good. Although it is dangerous and uh those
104:19 who've worked in the field with dynamite usually had one or two close calls
104:23 some kind of myself included. um better not to work with
104:31 Um Then the other, our other source, of course, on land
104:36 uh the vibe, the vibratory And in this case, we have
104:43 some kind of method of putting down a base plate and shaking the base
104:48 . And those guys come in smaller like this one, which is similar
104:53 the one that we have at the . In fact, this is ours
104:57 the university. And uh then you put a lot of them together if
105:02 want to get a much deeper uh or a lot more energy into the
105:08 . So in this case, it's and it sweeps or moves through a
105:13 of different frequencies and that's maybe over course of uh 15 seconds. And
105:22 you want to do that is you put a lot of energy into the
105:27 , but you don't have to do all at once. So when we
105:36 up all the energy that's put in ground, it might be the energy
105:41 of setting off a lot of But we haven't damaged the, the
105:50 or waste a lot of energy in rearranging the near surface. We've
105:55 a fairly low amplitude but vibratory sweep the earth and then we can just
106:01 afterward and make it look like it dynamite. So that's the beauty of
106:06 vibe. In fact, I was on the uh the Langseth ship
106:15 Which is um a big vessel. the main National Science Foundation, the
106:19 American uh science ship around 70 m . So it's um what 250 ft
106:27 ship. So it's around almost as as a football field. Uh I
106:34 have a chance to post the but um we went down yesterday and
106:38 a look at it and they have air guns. So in the marine
106:43 , which will show you put release air in the water, but they
106:50 a lot of backflips to satisfy environmental constraints. So in other words,
106:59 uh you have to let the hair , air guns hiss for a little
107:02 . If there are any marine fish or anything turtles around, then
107:07 they'll clear out if they don't like . But there are a lot of
107:13 jurisdictions that just say, you know , you can't do any seismic shooting
107:16 , including the east coast of the . We don't care what you
107:20 The answer is no, whatever your is, the answer is no.
107:26 uh so there's a big push to to figure out. Well, how
107:30 we gently put energy into the ocean that it doesn't even begin to think
107:38 disturbing mammal populations or anything else. the only real way to do that
107:45 to do it slowly and gently over period of time. So people are
107:51 to develop a marine vibrating source that be low amplitude, not irritating and
107:58 do that for a long time and correlate it and make it look like
108:02 big big big bang. So that's , that's part of the idea.
108:07 hasn't um, hasn't really caught on . But um just looking at the
108:16 of the tar, the tallest they typically have three wildlife observers on
108:20 to look for any whales, anything all. And um and then they'll
108:26 or change their shooting to uh accommodate . So once again, here's
108:32 uh here's the kind of marine an impulsive source where you have a
108:37 air and you've got some air uh devices. So you compress the air
108:44 then just let it uh go into ocean and just compressed air that causes
108:48 bubble and then the bubble is a and that travels through the, the
108:52 column and into the sub bottom and and reflects. Then we have streamers
108:58 or hydrophones or pressure sensitive devices and record the ref reflections or in our
109:04 , the borehole, we're gonna put tool in the borehole and record these
109:09 air gun sources. So that's the idea. Um And we can see
109:19 with 2020 vision. So we've got , well, we're gonna have the
109:25 and grab all the waves that are in the well. So how do
109:31 receive the data? Well, it's our simplest case is with a multiple
109:36 GE phone. So we're gonna put tool in the, well, and
109:42 one son, son, um such , in this case, it's uh
109:54 like to affix the tool to the wall somehow. Just so when the
110:03 is propagating through the earth, we grab it with the tool and we
110:07 do that a few ways. Just the mechanical arm, the mechanical arm
110:11 the receiver to the uh to well, if I'm in a cased
110:17 , and it's iron that I could have a rotating magnet and turn on
110:21 electromagnet and then attract the tool to uh steel casing by an electromagnet.
110:29 one way or the other, we like to get this tool affixed to
110:36 whole wall so that we could record vibrations. And then ideally, we'll
110:43 a lot of them so that we put a lot of them in
110:47 in the well and then shoot once acquire that data all the time just
110:51 one time. So if I've got five level tool, I'm gonna shoot
110:57 , move shoot, record move and gonna have to shoot and only record
111:03 traces. If I had 100 level , I could just shoot and record
111:07 the traces at once. So that's better. Yeah, of course,
111:14 level tool is gonna be more expensive a five level tool. So Most
111:20 the tools now are gonna be at 11 levels. So you're not in
111:24 well, too long because remember that got the, well, and I've
111:29 instruments and if I'm logging, it some time to log. And so
111:35 means that the, the drill rig to be still on site and it
111:41 be $10,000 a day or if I'm , it's $1 million dollars a
111:51 a million a day for a drill . Wow. Yeah. So,
112:01 , you can't fool around. So not even really the instrument that or
112:08 recording or all the geophysics. That's the expense. The expense is just
112:13 rig or the vessel. So typically we're making these logging measurements or E
112:22 P people want you to get in do your work and get out of
112:27 . So that's, that's part of deal. So some people always
112:35 wonder why geophysicists are always in a in the field. Why are GE
112:42 always in a hurry in the field them money? Yeah, because you've
112:50 got all this equipment and there are there are a lot of things about
112:55 equipment. Number one, the equipment effectively costing you, you want to
113:01 it in use all the time, it does cost you also, when
113:09 doing stuff, when you finally get working, you want to continue to
113:14 because you're always afraid that something's gonna and go down and you're not gonna
113:20 data. So once you get everything , let's just keep going, keep
113:25 , keep going, keep going because gonna break, something's up, something's
113:29 go wrong soon. And so don't . So that's the other thing.
113:36 then often we're using power supplies one or the other. You're filling up
113:39 , you're doing something, you're using . And so you're typically a little
113:45 in the field because it's expensive. got people clearly you don't want things
113:51 break and go down and you're, , you're using resources, whether it's
113:56 or storage or some little thing. always concerned that, um, you've
114:01 people and equipment and power and storage everything going on. So you want
114:05 do your job well, because you aren't going to get a chance to
114:08 out there again. So you don't because in the well location, the
114:13 on site. So in a day two, because the holes drilled down
114:19 day or two, they're probably gonna to demobilize. So you've got this
114:24 where you have to get the job , it has to be done pretty
114:28 and you're not gonna get a chance do it again. So don't screw
114:34 . So those are the uh head the field requirements. So, uh
114:41 that all goes ok. And people lots of practice and obviously things do
114:45 up every once in a while and the way it is. Sorry.
114:54 that's how we make the measurement. then, like I was saying,
114:57 going to have planned it before. What kind of tools are we going
115:00 use? Uh How deep do they to go? So, for
115:05 the simple things, how big is well itself, uh I gotta get
115:09 right size of tool. If I to clamp to the formation, then
115:12 have to have an arm that will so far enough, simple,
115:16 practical thing. If it happens to a very warm well, a hot
115:20 , then I need to know that instruments will stand that temperature if we're
115:25 pretty deep. And if we're gonna down really deep, can the instruments
115:29 that kind of pressure? So for wells, of course, none of
115:34 is such a big deal. But we start to get more extreme
115:37 deeper wells, hotter wells, caustic , H two S wells, all
115:43 kind of stuff. Uh We have plan for those eventualities. So
115:52 we often call this the original, was called a vertical seismic profile because
115:56 the day, almost all of our were vertical. Sorry, my thing
116:04 mute. Yeah. Yeah. So everything was vertical. So we called
116:09 seismic, a vertical seismic measurement, vertical seismic profile. Well as we
116:15 in the US right now, almost the wells end up being horizontal.
116:24 most whales will start off vertically in life, but they will deviate and
116:29 horizontal shortly thereafter. So while everything to be vertical in it, that's
116:36 easy to understand. And we still uh measurements in the vertical parts of
116:42 horizontal. Well, before it kicks and goes horizontal, uh most of
116:49 wells end up being horizontal now and still make measurements inside them. Now
116:56 get tools inside the well, we have to put it on coiled tubing
117:02 we might have to have a sensor the drilling color right by the drill
117:08 or you might have to tractor it where there's a little device that will
117:13 and drag the tools in. So are all kinds of different ways that
117:17 can get a seismic or a motion in the well, now what we
117:24 , we can start to see here on the right is we've got depth
117:36 then, and the upper part and shell section, we just gonna maybe
117:41 a shot every Um sparse location, every a couple 100 m which I
117:48 because then we don't get very well data. But then you might start
117:53 sample much more closely in the areas interest. And you can see what
117:58 what kind of information you get with different types of sampling. Clearly.
118:02 we're sampling more closely vertically, when got a lot more traces, then
118:06 can see much more of what, happening with multiples and with reflections.
118:12 when we sample really intensely, then start to see all the waves and
118:16 get much, much better resolution. can understand better. I can process
118:21 . So as always as geophysicists, want more data. And that's why
118:33 engineers, other people get mad at because that's all we want. All
118:37 guys wanna do is spend money and too much time. OK?
118:45 we'll get it right and you guys don't get it right. So there
118:48 go. So in terms of when happens, typically the V S P
118:56 , will drill the well, uh got casing in the top, it
119:00 be open hole on the bottom and we're going to do all of our
119:04 . And then the V S P typically come after that. So we
119:08 make the measurement encased well or in hole. And then ultimately, if
119:16 well is case, we can still measurements inside the casing which the uh
119:21 drilling engineers would prefer because they don't instruments going in uncased wells just in
119:27 they get caught or stuck or something . So, um, that's
119:35 Now, if we wanted to uh permanent monitoring, we might and take
119:42 instruments and even cement them in the , the outside of casing, which
119:48 more and more now with fiber for optics. In this case, we're
119:56 installing um G phones outside of casing then somatic men and you can see
120:08 standard kind of uh drilling and, logging operation here. And then we
120:14 we arranging all the instruments to put the well and uh cement it outside
120:20 but in the well, so that can make all these measurements.
120:27 So what do we, uh what we really want? The BS P
120:30 ? And here are a couple of original ones we talked about integrating or
120:34 the Sonic log to get time to , which is one way that we
120:40 get that time to depth relationship. it's a little bit funky because the
120:44 log might have problems in some place another. And it only measures really
120:48 to the well. So the most way to get a time to depth
120:53 for seismic analysis is from the DS . We just have a size,
120:59 just have a phone at different depths then we just whack the surface and
121:03 measure the time it takes to get that depth So that's the true seismic
121:08 to death from the DS P. that, just from knowing the energy
121:15 arrives at this depth and the, time it takes to get to this
121:18 , we can take the interval, depth change, the time change.
121:23 that gives us an interval velocity. we can calculate interval velocities pretty
121:28 We might want to know something about . How does the energy decrease in
121:34 as we go deeper? That can an attenuation or a Q A quality
121:41 calculation. And then uh you if we walk source away, we
121:53 get some ideas about the directional dependence velocities. And so we like to
121:58 that too. So we from the from the V S P, we're
122:04 gonna make another log. It's gonna a velocity log and attenuation log and
122:09 going to look like any of our logs except it's gonna be a little
122:14 more sparse with normal well logs. did we say that there was a
122:20 every what interval or what depth when look at the well log all the
122:28 points in the well log is that , somewhere around the foot. So
122:35 , so the well logs are output value about every foot. The VSP
122:42 the receivers are spaced about 30 ft . So it's really out putting a
122:49 about every 30 ft or something like . So vertically speaking, it's much
122:56 resolved. It's still a log, it's a very low resolution seismic
123:06 Then we're interested in um in that like any other log. But also
123:11 now we're trying to understand surface we're trying to understand if I go
123:15 shoot a big five survey with surface . Um what's happening in the sub
123:23 , you know, the service receivers , are getting all the echoes,
123:27 I have to infer what's happening in subsurface with the V S P.
123:31 actually got G phones inside the earth I can see inside the earth what's
123:38 . So that gives me ideas about source signature, uh what's happening with
123:43 the multi pathing. And then I also start to look at walkway effects
123:48 get the amplitude versus offset A V responses. So which, which you've
123:57 five courses already? Stephanie. sir. So which ones did you
124:03 ? You had? Um I I think it was seismic wave theory
124:10 Doctor Thompson, uh rock physics with um I think it was seismic interpretation
124:19 doctor and uh the potential field methods Doctor Bird, right? OK.
124:29 , good. Well, um hopefully seen some of this stuff a few
124:34 and it continues to sink in and no shame in that. I have
124:38 some of this stuff at least 50 and I'm still trying to learn
124:46 Yeah, Doctor Z's class kind of me a little bit. That one
124:50 a lot of seismic. So, . Well, and, and you
124:56 into a lot of the, um little details and when you're a seismic
125:00 and you're doing research or processing or , you really are in the
125:06 you know, that's, that's where is. You're, you're trying to
125:10 coax out little little details and so want to um do everything you
125:18 But um and in, in a , the V S P sort of
125:21 some of that. So now we're getting these rock properties from
125:25 We're getting logs, we're getting to how waves propagate. But we're also
125:32 this uh interpretation that takes well logs seismic. And so we, we're
125:39 see again how to uh how to all that. Then the other big
125:46 is that we have, we want make a picture. I'm trying to
125:49 a picture of the subsurface. And , the world doesn't really care what
125:53 of picture it is. Just give a picture that shows where, what
125:57 rocks are, what's their geometry and in them and how do I get
126:01 . So give me a picture that me that that's, that's our
126:08 And so the V S P is technique that allows us to, to
126:13 a picture. Now, there are lot of reasons why we do want
126:30 put the uh the receivers inside the . And one of the big reasons
126:40 that it's just a lot quieter. if we, if we look at
126:47 the vibrations that are happening in the , there's surface waves propagating along,
126:52 , there's traffic, there's all kinds stuff happening. But if I go
127:01 deeper into the well into the then a lot of that cultural
127:06 um industrial noise, environmental noise, that stuff has been damped out and
127:12 not propagating. So down deep, very little vibration happening artificially. So
127:20 ambient or environmental noise is much, smaller and here's just one such
127:27 And do you remember the DB I know it's like decibels but I
127:37 remember like the specific scale. it's just a, it's a,
127:42 just a faster way to give a that expresses a ratio. So that's
127:49 it is. It's just really the of a ratio. So with the
127:53 scale, you're, it's always two . It's how much bigger or smaller
127:59 one thing compared to another thing. explicitly, it's amplitude one over amplitude
128:13 , the logarithm, the logarithm of based 10 about that times minus
128:19 So what it means is that say here, We would say that at
128:30 ft deep, the noise is 60 less than at the surface. And
128:39 what does that mean? It just that the surface amplitude over the moral
128:47 is 10 to the third, the base 10 of 10 to the third
128:51 just three. We just take the for the base 10 and that's minus
128:56 . So minus 60 DB means it's , 1000, the value of the
129:06 , Which is incredible. So it's times more noisy on the surface in
129:11 area than it is at 900 m feet. So if I wanted to
129:19 get a much better reading Of what's I'm trying to do a tele seismic
129:26 receive uh an earthquake. Then by my receiver down 900 ft it's
129:33 way, way quieter and I should able to receive much, much smaller
129:39 and get them. So here's why we do this one? Suppose the
129:43 owns 150 ft underground. How, the noise level? What's the relative
129:51 level? isn't it just that 40? Yeah, but then convert
129:57 to the actual amplitude differences. Oh So at 150, it's for
130:20 So surface sample and I just tried . That was say that the borehole
130:35 the surface amplitude is, well, the borehole amplitude is one.
130:41 What's the surface amplitude to be How much bigger is the surface amplitude
130:47 the borehole amplitude? Oh, 1000 ? Is that what you're saying?
130:53 , that was that one specifically? , for this one specifically, I
130:57 the J phones at 150 ft How much more quiet is that than
131:03 surface? So, if about 150 I've got a noise level of
131:14 What's the noise level at the surface to this graph? Oh, so
131:25 it would be. So I'm convert 40 DB and tell me what
131:30 surface amplitude is. If the borehole is one. OK. I'm not
131:40 gonna lie. You've lost me. don't, I don't know what I'm
131:46 . I wanna convert it. I'm . Well, this is, this
131:50 really just manipulating the D V OK. So I, I would
131:56 just uh figure out how to use D V scale. And so
132:05 if I say that the, uh my borehole amplitude is one and that's
132:14 DB down from the surface, then means that this is minus 20 on
132:22 left hand side to the minus 20 10 aptitude one over aptitude two.
132:30 minus 20 here is minus 20. means it's just one. So the
132:34 of base 10 of one is one is 10. So that means that
132:40 surface aptitude is 10 times the moral . That's what 20 BB means.
132:47 DB is a factor of 10, DB is a factor of 100 60
132:52 is a factor of 1000. So that's just the DB scale.
133:04 you might say, well, why you just say 1000? OK.
133:08 was like, I don't know what's . Yeah. Well, when you
133:13 , it's just that it's a, smaller number to say 60 DB.
133:20 the scale is defined as a logarithmic that's defined to make all the numbers
133:29 and able to express uh a big value. It's like in
133:34 the, the scales are logarithmically plotted that you could put a whole range
133:39 numbers and give them a, Give all some, some weight from .2
133:45 2000 or something. If we had a linear spacing between all those,
133:51 all the small numbers like from 10 would be Miniscule because I've divided it
133:58 linearly to 2000. So that's why plotted on that logarithmic paper because that
134:04 everything. Uh Likewise here with the DB is just a complicated way
134:10 give you a ratio. So if surface amplitude is 1000 times bigger than
134:18 bal amplitude, that means 1000 over , the logarithm base 10 of 1000
134:24 the larger than base 10 of 10 the third, which is just
134:29 So the magnitude ratio and, and or DB of 1000 to 1 says
134:38 the one is 60 DB less Or times 10 to the 3rd less.
134:46 that's just the DB skill. It's just a faster way to Talk
134:55 two numbers, how much bigger or two numbers are. So, I
135:04 the surface amplitude, it's really noisy it's a million times bigger than the
135:10 amplitude. So on the surface, it's a million times bigger than say
135:16 at 18, m. So I could, I could write that
135:24 and say, OK, it's a times bigger or I could just take
135:32 million is 10 of the six. this number is 10 to the
135:37 the logarithm based 10 of 10 of six is just six. So it's
135:44 DB different. The negative is expressing I want to see how much smaller
135:57 guy is than this guy. I call it a positive. I could
136:02 that the surface noise is a million bigger than this guy or that this
136:07 a million times smaller. If it's , I'm gonna say it's negative,
136:11 bigger. I'm gonna say it's So, you know, 100,000 is
136:17 to the fifth. We just take exponent five multiply it by 20.
136:22 100 DB. The reason to harp this a little bit is that in
136:31 lot of literature, you're gonna not it go from one to a
136:38 The scale is gonna be plotted in from zero or 10 of the 01
136:45 to minus A B which is 10 the fourth, that's 10,000. So
136:50 gonna, most of the scales are be plotted in DB or how much
136:58 from the maximum value are you So this is just a uh a
137:06 to compress The ratio of two And the equation is here that the
137:18 , the relationship between two numbers, any number X one and X
137:24 whatever that, is we just take logarithm to base 10 Multiply it by
137:32 . And that's how much smaller one than the other. Just on the
137:35 scale. It's named after Alexander Graham . Because what they needed was when
137:43 were trying to transmit signals across telephone signals, the telephone signal would
137:51 off with distance. So they would to say, oh, the telephone
137:56 fell off by a factor of one over this distance. And they wanted
138:03 faster, shorter way to be able say that same thing. And so
138:07 said from its starting point to its point, here's how much it decreased
138:13 GB. And so everybody knows that the amount of decrease from one one
138:22 to another point. And if you at music magazines or anything, there's
138:30 a magazine that was a popular um magazine called Downbeat, which was a
138:38 on DB. But on all the , the uh recording engineers scales are
138:46 every geophysical graph. You'll see that's two numbers or looking at some kind
138:53 energy or wave propagation is gonna be in DB. So you need to
138:59 that if that's a logarithmic scale. . So that's, uh,
139:05 it gets quieter. Um, we're gonna do one little thing and then
139:09 can, um, break for the . Let me just see this one
139:16 thing to get us our brains working then we'll go to Friday night.
139:23 think my brain is hurting right It's right now. Ok.
139:26 let's leave it for tomorrow. uh, word we've had a big
139:32 . Uh, So we'll see you morning at nine and then we'll,
139:39 do a couple of little more exercises and, and then, uh,
139:44 then go on from there. So we'll do more V S P and
139:47 more exercises and, and, get that chunk done. Ok.
139:56 . Um, just for strictly completion , uh, let me quickly
140:31 Just because I mentioned it. Let's do this one and then, then
140:35 off. Um, So Stephanie, can see here again. We've
140:43 uh, another example. So the is, we've got a well
140:48 We've got a geo phone at 68 ft and then the energy is going
140:53 , down, down, down, and it, We recorded again at
141:02 ft. So we imagine that we've got energy that's going down the,
141:08 , It passes the G phone at 76 at this time and then it
141:14 down to the bottom of the, , at this time. So,
141:18 is the average velocity across this Then we can move on to Friday
141:29 . Bye. So the bottom, bottom depth is 11 930. That
141:39 depth is 68 76. The waves going across velocity is delta Z over
141:45 T how long does it take to from one to the next? Dep
144:19 been talking this whole time. I not realize I was on mute.
144:26 . Yep. Sorry. I just some water. No, you're
144:30 I was talking my way through it then I realized I was on
144:33 Oh, ok. Yeah. Um got Like, if I didn't.
144:39 . Which I hope I did. got like 63 ft per millisecond.
144:49 I did 1193 -68, 76. then I did for my time,
144:57 11,930 is like around Like 10 80 1000 for that 68 76.
145:09 So watch your pick 1080 or is right? It's almost 2000. I
145:19 sure of the units. It's No, I'm at not the,
145:27 units like the, the sectioning. . 10. Well, you can
145:35 that it's one second in two seconds 1000 milliseconds and 2000 milliseconds. So
145:40 just one second, two, three second. Uh-huh. And there
145:45 10 little blips between it. So 100 milliseconds each. Oh, they're
145:55 oh, I meant 1800. Not 80. You did. And I
145:59 that I was wondering like I was , I was like that doesn't look
146:04 . Um 50 54 Divided by OK. So 6.3, 6.3 Watt
146:17 per millisecond. And then how many per second is that .63?
146:35 It would be 50 54 Divided by 028-07 88. Not 1.8. So
146:57 sounds right to me. OK. there's the calculation. So we've got
147:08 , the, the depth interval which 11 9, 30 minus 60
147:14 And then I picked 1.82 seconds or milliseconds. So that's really just,
147:31 gone this deep and it's taken that time. We've got Z over T
147:38 is 63 97 more or less. . Good. So that, that's
147:44 . Again, this is, this a real data case. The guy
147:47 it to me from the Gulf of . And so this is exactly what
147:50 would do. And now we know interval velocity, the actual true seismic
147:54 velocity over this area in the Gulf Mexico. So that's um and that's
148:01 that we need to know for the physics, for the um for the
148:07 , for the time to depth for lot of different reasons. And so
148:10 is uh manipulating some real data and , the reason to bash away in
148:15 units and everything is so that you look at this fast and know
148:18 And then like you're saying, get sense of is that right? And
148:25 know that we just talked about is around 2000 m/s. So if
148:33 takes, it takes a second to 6000 ft, it takes a second
148:40 go around 2000 m. So this even at depth in the Gulf of
148:45 is around that 2000 m per second . So now this is just one
148:55 time because this is the energy going . But if you double deck,
149:07 would get somewhere around or 1000 right? Mhm. Which um We
149:37 that should be somewhere around 4000 right? If if our little equation
149:44 . Mhm And this is about 12,000 , which is around 4000 m.
149:56 and we just calculated that the velocity 63 97 which is around 2000 m
150:02 second. So guess what? We tell any really big stories there?
150:08 was, that's all makes sense. how long is it gonna take to
150:13 down 4000 m around and back around milliseconds or four seconds? So if
150:23 came up to you a good old from the Gulf of Mexico Exploration Team
150:30 said, hey, Miss Smarty pads we're paying you I got the seismic
150:36 in this vessel. Wanna tell me long to record my play is down
150:40 12,000 ft and I don't use stupid units. So you better tell me
150:45 long I need to record and you'd , oh uh yeah, five seconds
150:50 be safe. Wow ! Ok. like you sometimes. So these are
150:58 uh we wanna be able to manipulate stuff so that you rapidly can get
151:04 answer even with simple stuff because we to have a secure answer and you
151:09 to get it fast and then when get more complicated, you can say
151:14 should be around here and if it's , I'm getting worried. Ok.
151:22 . Well, that's a little bit metal aerobics and now you've done it
151:24 so now we can guilt free, and enjoy a few minutes,
151:30 Ok. Great. Stephanie. We'll we'll see you tomorrow. Ok.
151:34 you so much. Cheers. Bye
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