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GEOL7325 Petrophysics and Formation Evaluation - Day3 10-06-23
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00:00 Mhm Last week, pretty much introduction things. What data do we
00:10 How do we get the data, large audience and how do we get
00:16 data? Now, we're gonna start talk about how we use the
00:21 So how do we evaluate hydro Talked about what we wanted to know
00:26 kind of data there was the value core and the value of cuttings,
00:31 side walls. So um basically, gonna be two ways we do
00:38 We're gonna, there's two main ways we uh evaluate hydrocarbons. So one
00:45 on a concept of balance forces that height modeling, which we looked at
00:51 , remember we talked about we're balancing forces and capillary force, right?
00:57 we're overcoming a tension at four walls buoyant force. And uh if you
01:04 the exercise that allow you to basically everything up into including if you have
01:09 cap like pressure curve, you can with quite some accuracy, the permeability
01:16 , uh et cetera where the hydrocarbons and function of depth, all of
01:21 . So very powerful method. Next we're gonna look at spend most of
01:26 rest of the course, looking at of it and most of it is
01:30 resistivity to evaluate hydrocarbons, which to , it always amazed me, somewhat
01:37 forces. I could understand that physicist training, but uh in something like
01:43 rock, be able to measure resistivity quantitatively determine what the oil saturation
01:51 Uh It's uh pretty fascinating, main we can do it, get rid
01:58 them. How do I get? gotta click on this. I guess
02:16 , all right, thanks. It's . Yeah. OK. So little
02:27 of magic here. But why can do this is because we really only
02:31 one source of connectivity, particularly when start. The only thing that conducts
02:36 the brine, it's gonna be our assumption. So really what we're measuring
02:41 the amount of brine that we have the nation. Uh Interestingly enough,
02:48 find it interesting, this is related the uh amount of high amount of
02:53 using a Power Law called the Arch . It's not linear what, what
03:00 might have gas. And we're gonna through kind of a detailed understanding of
03:05 it's Power Law and what all of parameters in Archie's equation. So this
03:10 uh one uh remember I told you uh three equations you're gonna have to
03:16 is that relationship between pathway pressure, surface tension contact angle and poro
03:23 right? That's one the one you for the saturation hide model. Uh
03:29 equation and then Archie's equation. Remember I stated about uh by, remember
03:37 , you're gonna have to know what equations are, what all the terms
03:40 them means. And then be able describe uh some elementary way how it's
03:46 , right? Don't misunderstand what And so we're looking uh like I
03:53 already, we're gonna send them the resistance. We're going to assume that
03:58 rock matrix quartz is quite a good . It's a pretty standard insulator,
04:04 ? So very high breakdown pressure. quartz does not conduct hydrocarbons do not
04:11 . And when we're going to run trouble is which we will talk about
04:15 this class. Since you're mostly geologists clays are what causes us to have
04:22 stem the Archies equation to a shay . So we'll talk about that in
04:27 too. First of all, you under the lamp post first, we
04:31 the simple things first, not the equation, but that simple. It's
04:37 I would play magical and how well works. So we, first of
04:43 , like everything we've talked about so , we need to, to find
04:46 vocabulary. So rw is the first . This is the water resistivity,
04:56 formation water resistivity. And I stated least up to the end of this
05:02 . Uh Maybe the next we will only uh the only thing that'll be
05:07 is the brine. OK? It's function of water salinity and temperature.
05:11 look at that uh how that I think a lot of it's obvious
05:16 happens with temperature and salinity. All . So our, our, our
05:21 this is a resistivity. This is intensive or extensive property intensive. Everybody
05:33 what those are. Yeah, intensive depend on the amount of material extensive
05:40 . So we want to determine a of the formation which we will then
05:46 aerial extents and things like that. we know a saturation, an intensive
05:51 , right, we will be able build an extensive property. What our
05:57 of oil is. Other words, much our formation at least one good
06:02 how much money our formation is Yeah, hopefully it's clear what we're
06:07 do. Uh Next is R oftentimes called ro, but it really
06:16 zero. And what we mean by is zero oil, you can see
06:24 trans spread. I don't know is a transcript being generated? Usually?
06:43 my English is that bad? All . Uh So it's the resistivity of
06:51 rock when the water saturation, which already talked about, right, is
06:57 number. What a saturation. What we normalized to? What's the definition
07:02 water saturation? It's the volume of normalized to the poor volume. Remember
07:12 we got from that normalization to a volume. Clearly not studying your notes
07:23 right. So we multiply the saturation porosity, porosity is the volume for
07:29 volume, saturation is the volume of per po po volumes go away.
07:34 gets the volume fraction of oil per bulk volume. That's one I really
07:40 remember gonna get used. You're gonna asked in the midterm. You're gonna
07:45 to know that. OK. Derivation quite trivial, but I don't think
07:50 too much to ask. Would you that? It's a volumetric kind of
07:56 which I will expect you to be to do. So, it's clear
07:59 RO is. So, Ro is greater than RW has to be.
08:07 , we're gonna go through a mental which geologists tend to be very visual
08:11 right brained. I'm told that's also for me. So I like these
08:17 mental models for how we are going build a rock. So we are
08:21 gonna go through that. I think important for you to understand that mental
08:26 , right? But pay attention rwro greater than our W and basically,
08:34 have taken a brine which we measure W for, we will add a
08:40 grain like belts bar to it. therefore, the resistivity has to get
08:46 . Our W remains the same. what happens is my, um my
08:51 of water will go down and the of the current we have to blow
08:56 all those brains will also cause the to be greater, right? Not
09:04 whether we'll talk about tortuosity but that's ratio of the length of the current
09:10 to the physical length of the We're measuring the resistance through measuring the
09:16 of or that he's OK with It's obvious why Ro has to be
09:21 than RW adding a non conductive So this is my mental model.
09:28 illustrate that we start with a tub water, some tube, we're gonna
09:34 the resistance across it. We're gonna the dimensions which allows us to get
09:39 resistivity, right? And then we dump a bunch of quarts in here
09:45 the water is gonna overflow. We worry about that, right? So
09:48 have less water in here. We're measure the resistance again, or the
09:54 again. Clearly, it's got to greater because we are adding a non
09:59 material to it. Huh Again, current has to go. I lost
10:05 point. Nobody pointed that out. getting pretty good at doing that out
10:11 class in the face because we have go around all of these brains.
10:17 so two reasons why the resistivity has larger. Next thing we're gonna do
10:22 we're gonna do this in separate stages we're gonna add oil to this
10:28 Oil is again, non conductive. what's gonna be my resistivity when I
10:34 that and be bigger, the activity be larger. Oil is non
10:42 And I want you to notice the we're kind of doing the same
10:46 we have oil trapped in the poor , right? We are reducing the
10:51 of water, we're increasing the So we expect the equation Arching equation
10:58 covering saturation to be quite similar to happened with broth. And see in
11:03 second, that that's true. We're OK with that. By the
11:07 we call that resistivity. Once we the oil RT, if that's
11:14 yeah, we're here. We'll call . That's called our T for the
11:21 resistivity. Why is that? When study resistivity logs, we'll understand why
11:27 calling it true. It's because we're resistivity, it's unaffected by four hole
11:36 , what we want. And that's number we want to plug it into
11:40 equation to give us a saturate, ? Everybody's still OK. This definition
11:48 so dark. So uh fundamental interpretation , when I say you need to
11:55 and be able to write down Archie's . I mean, all of
11:59 right? We're gonna define what the factor is. Formation factor is.
12:04 ratio. It's ro divided by That's bad. This is actually pretty
12:13 what happens to RO if I double after it's a constant fight F is
12:24 property of the rock which is kind analogous to permeability that a talked
12:32 right? So it's a function of tortuosity, but it will be different
12:38 pay because it doesn't depend on brain like grass and Yeah. Yeah.
12:54 is the true resistivity of what we measure far away from the boreal
13:01 oil includes water, foods, aros sector. Well, we'll show the
13:07 of that sector. All right. this one's fun. Now, uh
13:12 of my favorite parts of talking about equation is this Power Law behavior.
13:19 sees F is equal to one over to VM. That's a Power
13:28 Typically M is somewhere around two greater two can be less than two.
13:35 is no fundamental reason. It should equal to two. I could talk
13:42 that if somebody really wants me right? What, what that
13:46 Right. But what happens if my actually goes down by a factor
13:55 My formation factor does not change by factor of two. It changes soon
14:01 is equal to two, two squared four. So my resistivity has gone
14:07 by a factor of four. So is one of the cool things about
14:13 is that your resistivity is a strong of porosity and saturation. So it
14:20 it fairly sensitive to adding oil. why I'm dead. Now, this
14:27 here, this did not appear in original equations. This C people put
14:33 in. Uh And we will understand C uh what C demonstrates is that
14:40 complex four systems, Archie's equation doesn't hold through this form. This is
14:47 quite remarkable. By the way, I plug a porosity of one
14:52 what do I get for one to power is one. So at A
15:04 one, we are back to our of water, we have added no
15:09 . So we have to get back that point. Everybody see that one
15:17 any power, one squared is one to the half, power is
15:22 tub is one. It's a multiplicative , right? Ok. That's actually
15:29 remarkable. This in general holds for reasonably well means I can go all
15:37 way from a porosity of like, know, rocks that ranges in porosity
15:42 . A G's equation will be that from a porosity of, I don't
15:46 , 5% maybe even lower all the to a porosity of one. You
15:53 not be surprised by that, but are still continuously surprised. What does
15:59 mean that my rock behaves in a consistent way all the way 90% of
16:06 90% of my rock being rock to of my rock rocks are complicated things
16:15 that to work. That simply is a what we will be finding.
16:21 , is that in carbonates, this often not true, this does not
16:28 . Hence C gets added. And C tells you is basically some idea
16:35 how much of differing core systems are there to people. Because what happens
16:44 if I set B equal to one this equation B to the M is
16:50 and it states that at a porosity one no rock, my formation factor
16:55 no longer one. Therefore, my of my grine somehow is not
17:04 That's clearly incorrect. Everybody understand So what this means and you will
17:12 this elsewhere. Yes, I've already it. It means that this equation
17:17 locally true in a mathematical sense over limited range, right? It will
17:24 , but I cannot extrapolate this too . Well, hopefully understand that when
17:30 get carbonate. But for now, classics, we are always going to
17:37 that s equals 11 core system is and that we can use Archie's equation
17:43 of straight from his original papers. go back and think I might have
17:49 , given you one of his original . This is what he did when
17:53 plotted the data, he got a line on a log log plot and
17:57 came pretty close to f equals 11 equal, right? We're all OK
18:05 that. But that's an important particularly when we get to carbonates,
18:09 gonna have to understand this detail, ? And this cementation is a
18:17 I must have looked at 30 40 sets in my call it a career
18:23 this stage in my life in my . And I have never found that
18:29 dominates given the facts, plastics. we're gonna find is it's about clays
18:37 and carbonates. It's about bugs versus ferocity. Determines what, what determines
18:46 values of M and what we'll N in a second, right?
18:49 parameters in a. OK. Should go into what a fractal is in
18:56 class? You're all geologists? Everybody what a fractal is. Nobody knows
19:04 a practical is. At least a of, you are willing to admit
19:10 . I didn't know it at this and I was your age, I
19:14 did not know what was but uh a relatively recent concept. It was
19:20 in the late sixties, early seventies Mandel. However, you as
19:27 you physicist too should understand this because of the things you look at are
19:35 , four spaces are fractal, Uh coastlines are fractals, meandering rivers
19:42 are governed by fractal statistics. All these things are fractal. Geologists need
19:47 understand what a bra what is a ? The original, the original,
19:54 go back to Mandelbrot's original book, ? He explains, he introduces the
20:00 by the length of the coastline. . But you're measuring and I think
20:05 did it on the coastline in but it doesn't matter what coastline
20:08 You're measuring the length of the right? And you do this from
20:13 satellites, you have maybe a kilometer , you measure the length of that
20:19 , you'll get a certain number, ? So perfectly valid. I now
20:26 and I measure it a higher let's say at a resolution of 100
20:31 . I measure it again. Will get the same number? Come
20:40 you're all geologist. You look at stuff for a long time,
20:45 Very rugged. I increase my I'm able to follow the coastline
20:51 I will get a larger number. ? Ok. Increase my resolution
20:57 I can follow even more detailed ins outs of the coastline and I'll get
21:03 even bigger number. I can do . That were actually quite a few
21:07 of magnitude. I will keep getting and bigger numbers. So, what
21:12 the length of that coastline? The ? You probably want to know
21:16 right. But what's going on with coast, et cetera? Right.
21:22 old is the continent or whatever the is? You're measuring all of
21:26 Who's right? Nobody's right. Everybody's . There is no answer. We
21:38 up and don't worry about the So that's probably a good idea.
21:44 all want jobs. Right. So answer is everybody. Right.
21:53 You in order for that number to anything you have to define the length
21:59 the yardstick. What your resolution I can tell you if you're measuring
22:04 porosity in a rock. This is to be true too. When you
22:09 a thin section from a porosity, get the right number. Sorry,
22:12 you get a porosity from a thin , do you get the right number
22:21 ? Uh when is it significantly How about if you have clays because
22:32 will not typically have the resolution in micro thin section. You have to
22:37 to an SCM, I measure the sizes. So it's very standard to
22:42 too small a number even if you everything else, right? You get
22:46 small a number because you have not at the porosity on a small enough
22:50 scale to include everything, micro course or another or anything. Yeah.
22:58 all of these, you have to attention to the length scale and what
23:02 you pick up as you go to finer length scale, right? So
23:08 rate of change, however, what can uniquely identify and is different for
23:14 , the Norway than West is the of change of that coastline with the
23:21 of the ruler. Ok. So is actually the demonstration is he he
23:28 plot the length of the coastline versus resolution. What did he find that
23:35 a Power Law? OK. So coastline, if you tell me the
23:41 of the ruler, I know the of that Power Law, right?
23:45 interesting, I can tell you what you would measure. So what is
23:50 is the slope on that log log of the rate of change of the
23:56 with the size of the ruler So why do I bring it up
24:01 ? Because Archie's equation formation factor is Power Law. But what does that
24:07 you particularly given the explanation. I the last five minutes on,
24:15 resolution matters, right. Resolution And there are many length scales inherent
24:22 a, in a poor system. look at a micro CP volume.
24:27 don't know. Did we talk about a lab to her one day in
24:30 class? So again, we we settle on moving towards the end of
24:35 course if you'd like to do we just got our micro C up
24:39 running again. So I I would to show you actually a three dimensional
24:44 of a four system. Seeing my is believing and, and if you're
24:50 right brained as I am, it's it required to believe things people are
24:56 , you know, why should you me? Right, other than I'm
25:00 paid. So the M value just the value of the Power Law for
25:07 length of the coastline tells you the of change how many pores we were
25:12 up as we change length scale. a Power Law four systems fractal.
25:19 you implicit in that because we have length scales inherently measuring the OK.
25:25 it is pretty clear if you look a Catholic pressure curve, you see
25:29 if you look at uh uh permeability , those those are modeled by Power
25:35 resistivity is modeled by a Power Law in rocks. Power Law creep.
25:41 everything you measure that involves the poor obeys a Power Law. If we
25:50 a over the grains and the poor that breaks down the velocity doesn't ba
25:57 Law behavior. I was stuck on for quite a long time.
26:03 With what a, what a fractal , it's qualitatively what it means.
26:10 I ask you on a midterm, is the Power Law? What is
26:16 ? You would say many length scales involved in the measurements, right?
26:24 a Power Law actually allow you to that, right? Those length
26:37 What is this value scene? I'm beat that with that. So
26:45 you will see it's a great And one I asked myself, I
26:50 came from Michigan, right? Working nonlinear optics. Nothing to do with
26:55 . It gets to the old the oil industry, they're using this
27:00 . Nobody knows why, right? calls it empirical. So asked exactly
27:06 question, what determines the value of as petros? And didn't really get
27:12 piece of, we're gonna do our to answer that question and published it
27:17 , as well as a, a of the where it comes from?
27:23 . When I asked myself, maybe why I think it's great. All
27:27 . So that equals speed to the M. That's just OK.
27:32 Then the other concept that you're gonna , we're gonna, you're gonna use
27:36 do this calculation is uh what's called A which is an apparent water
27:45 OK. So you notice that here have rob to DM. This basically
27:52 the saturation is one. See why is the second we go through and
27:57 things. Ignore the fact that there be oil and we calculate a
28:03 we calculate an apparent water activity. of the ways people attempt to evaluate
28:11 a water is giving is, that's come up later in the lecture
28:17 OK. So you can do this empirically, which is kind of the
28:23 way to do it. But I strongly particularly you as geologists. Why
28:28 I say you should understand why the is changing because that gives you real
28:34 to MNC. What was RW It's the apparent water by apparent,
28:44 mean we're gonna ignore the effects of . We're gonna calculate RW as if
28:50 fully water sand. I'll explain how used. You, you look for
28:59 lowest resistivity that you calculate in this and you're gonna assume that's my best
29:06 for what the true water saturation is oil is gonna make the resist to
29:10 higher. You, you'll, you be doing that. So my last
29:18 I'm gonna add is oil. And , or we all believe that G
29:26 but F is equal to one over to the M I multiply that by
29:31 , I get my RO what happens I add oil? Imagine this is
29:35 water, wet rock right, which have some idea what that means.
29:40 , where's the oil gonna sit in water wet rock in the center of
29:44 core body? It's like if we , sorting it would put a crane
29:49 . So gee how would this have behave in much the same way?
29:58 . This gives us RT is the to the question that was asked
30:03 RT is the true resistivity. It the effects of adding oil.
30:10 And interestingly enough, this I found interesting uh This is a scaling loop
30:17 , right? Remember the scaling rule had that here. Let's just go
30:22 at this ro is just equal to number which was constant for the rock
30:27 RW by the way, that's gonna down. Yeah, it's not gonna
30:34 . This is one of the things gonna have to change this implied,
30:39 ? There's a simple scaling here. basically the geometry of the current flow
30:44 independent of the relativity. The what's happen when we add clays? They
30:50 add a source of connectivity. So geometry of my current flow will change
30:55 a function of sele. So that be salinity dependent. So RT has
31:06 be greater than, has to be than our old unless there's no
31:11 In which case, they will equal by definition. But if I add
31:16 , it's non conductive. And interestingly , I know you're all getting all
31:21 goose bumps, right? Like I that there is a scaling rule,
31:25 obeys a Power Law just like the factor did. There's a, there's
31:33 relationship between RO and RT. This due the I called the resistivity index
31:40 a function of adding oil that I like F was one over B to
31:47 M I is equal to one over to the N A Power Law.
31:53 . What does this mean? It that oil is introduced into the rock
31:58 varying length scales again, just like bros that to me makes a whole
32:04 of sense. Fact, one of assumptions and is called the saturation
32:12 One of the common, the, most useless assumption is gee let's let
32:17 Glen equal two, right? The reason to set that equal to two
32:23 uh is that it's one button on calculator. That's the only reason they
32:28 do of doing there is no reason M should be two or M should
32:34 two back in that. Um If were to make that is actually a
32:41 Shay rock. If you make that , there's a fair amount of play
32:46 it. If you have a very rock, M is an N is
32:51 to be closer to 1.61 0.7 to as low as 1.5. But that
32:57 be a right. So M equals equals two is bad guess unless you
33:07 there is a significant amount of We're gonna see that not too
33:10 but uh how about M equals N can talk about this. And one
33:17 the reasons I wanted to talk about ability, saturation height bottling first was
33:22 is a water wet assumption M equals means that gee the way when my
33:29 changes why rocks, water wet oil behaving a similar rule to that.
33:35 putting oil, it's sitting in the of the pore just like a grain
33:40 . So water wet assumption M equals if N is greater than M,
33:47 a mixed assumption. That means that oil is preferentially, right? Uh
33:55 towards the throats, right? Tending cut off connectivity more rapidly and agro
34:02 is fair enough for now, So it's called the saturation exponent.
34:14 it will depend on principle M does obviously depend on wet ability, there's
34:20 oil involved in it and gods. so RT, we can write RT
34:28 our old, old this to be water saturated rock divided by SWF.
34:35 here you can see for some nobody throws a sea into this
34:40 right? But you can see if water saturation is one, we end
34:44 back with our team just as That's pretty standard assumption. They don't
34:52 AC or ad or ad or whatever this equation. I think that's mostly
34:59 they measure it, right. No goes through that all. OK.
35:07 , on water saturation on a if you assume an equal two.
35:14 again, this just makes it I can hit the square root button
35:20 bite. Uh Again, only by . Would that be true? All
35:28 . So how do we get, get our o you have to know
35:34 the water saturation is to get that . So a lot of times that's
35:40 a useful thing to have measured. normally don't like to drill wells where
35:44 no oil. That's a lot of for not much return on our
35:48 right? But oftentimes you'll hit that you'll hit a water leg or you
35:54 through the pay zone will gets to you think the water saturation if you
36:00 , that allows you a way to RW. RW is actually barely,
36:05 , I know a lot of cases drill an exploration. Well, you
36:09 oil everywhere. How do I get water resistivity? Right. Put into
36:16 . Even if you produce water, lot of times you don't even produce
36:19 . You're all expert on Catholic pressure . If I'm not producing any
36:24 what does that mean? Just did exercise, right? Talked about critical
36:32 saturation. It means that our hydrocarbon is such that every well in that
36:39 , we are above the critical water , we will produce no water.
36:45 that's good news, right? That's we want. But if we're gonna
36:49 Archie's equation and we're gonna try to as we move away from that well
36:54 . Where do we start to encounter ? We need to know our water
37:00 . Also, what's gonna happen as produce that oil, we're gonna get
37:04 encroachment. Ultimately, we will start use water a lot of times the
37:10 way to monitor that is through a measure, we can do an open
37:17 completion. So we would love to the water resistivity, blind resistivity.
37:24 lot of times that's a hard thing get. OK. Sure. And
37:32 we could solve for water saturation, Archies equation. Again, there's no
37:37 reason and I really C is EC equal one in this course, except
37:45 where we explicitly understand why not. your standard assumption C is equal to
37:52 C came about through the and originally the, actually in classics, through
37:56 humble relation. And it's just they a cloud of point through a line
38:00 a gray their regression, even though correlation wasn't very good, it didn't
38:05 back through an F of one B one. This meant they didn't spend
38:10 time to understand the reason. So do we get our w we're gonna
38:14 about that. Next one of the things we're gonna do. Uh Next
38:18 we're gonna talk about uh permeability indicators pay zone indicators, the gamma ray
38:24 the SP and from the SP, can get RW, so we can
38:29 RW from a nearby wet zone from SP log. If we're lucky,
38:34 , from a water catalog or somehow can measure water, we oftentimes will
38:40 a core which we're experts on. have limited invasion in that core.
38:45 we can actually drill plugs from the of it and spin them in centrifuges
38:50 attempt to water and measure it. you have a lot of corn,
38:56 relatively un invaded. That's a plausible and a reasonable thing to try
39:03 just try that in swells in Alaska , we're gonna get from deep resistivity
39:10 . We'll understand that uh when we to resistivity logs, ferocity will get
39:16 logs which right after we do the indicators, density neutron and acoustic
39:22 So we're gonna talk about the rest this course. They may be way
39:26 the end which, where, where well talk about uh the NMR
39:32 I didn't cover it in the other . We're gonna cover it in more
39:36 later. Uh We'll see that's another to get process which they are,
39:42 was relatively dependent, not as much they claim. So we're all
39:49 That's basically what we're gonna do. . And then one, they have
39:55 access to that text or not. I do have it. I,
39:58 have a digital copy with if you it. It's a reason that text
40:03 a reasonable read. It's an easy . The only problem I have with
40:08 , it was written by an ex guy. So it's very heavily weighted
40:13 its log, doesn't give it for due in terms of calibrating the
40:19 As long as you understand that it's and still pretty valid. Getting a
40:27 old, uh, this, I I threw in because Archie's equation it
40:34 derived empirically. So that absolutely Archie brothers had just initially this was right
40:41 the war, right? And they World War Two and, and they
40:45 measuring resistivity. It's been a bunch wars since, right? So,
40:51 I would even say that. Uh so they uh so they were measuring
40:59 in well bores. He went through they had, they had the logs
41:03 the number of wells with the he was plotting up the resistivity versus
41:08 . So he empirically got this log plot, right, a reasonable correlation
41:14 however, you can start from Maxwells . Not sure if you know what
41:20 are. They were developed in the 18 hundreds to explain right? Radio
41:26 and things like that, put that together. You can start with Maxwell
41:30 and you can derive Archie's equation under known as an effective medium. Uh
41:38 include it because I love effective medium . They uh it's another way to
41:44 above and beyond the way we've averaged in 3d. One way to think
41:49 it, it's better than series and models. You could build models that
41:55 between series and parallel, right. hydrocarbons in place. So this is
42:02 volumetric notice the D times an oil , does that immediately tell you this
42:15 the amount of water per bulk Yeah. So it's P minus PSW
42:25 or one minus SW is so pso volume of water per volume. So
42:33 multiply times the height of thickness of formation, times its aerial extent,
42:38 get a volume. So we get absolute bought barrels of oil. Everybody
42:44 that BS W parts in particular comes all the time. This is just
42:55 from barrels right from a saturation for . He is in and A as
43:01 acres, not my phone. So gets you the barrels of oil and
43:10 gas is obviously the same thing. it has to be a reso
43:17 There is a correction to get that the surface, right? There is
43:21 volume extension. You actually have to that with oil too. This would
43:26 valid in the subsurface. Typically your it would evaluate under reservoir conditions.
43:32 this would be the number of barrels as in situ right, they take
43:37 to the surface. The oil right on the gas oil ratio but you
43:43 the oil down to actually ring, . All OK. And this is
43:54 we get it to the surface, gas. So we're 60. You
43:59 be asking yourself that's how we convert absolute temperature, right to basically uh
44:09 at breeze rank and it's an absolute , it breathes Fahrenheit. So it's
44:15 60 plus degrees Fahrenheit is an absolute pain. So we're 60 plus 60
44:23 5 20. I think this is temperature place. This is my reservoir
44:30 . 14.7. What exam is very ? 14.7 P si that's why you
44:40 live here. And then this is reservoir temperature. This is my,
44:47 is my uh direction from an ideal , right? The factor it could
44:53 through but I have to give up things otherwise, yeah, you wanna
45:01 through my petro food course, talk that quite a bit. So that's
45:05 an expression of the fact that in particular methane, whatever they are
45:10 ideal gasses. So you have to the ideal gas off. Otherwise we're
45:17 the ideal gas log to see who be one. Yeah, but the
45:23 factor and again, BS W et cetera, right? And then
45:32 you wanna book reserves, which a of executives at Shell got fired for
45:39 CO2 is not the same. It's , by the way, basically about
45:46 that's not the first people to do book CO2 as a reserve. It's
45:53 worth much, right? So uh have to have a recovery there.
45:59 what percentage in the gulf? For , what percentage of the oil that
46:03 recover? 10%? 50%? Which of those three we can
46:16 I'd love to have it be Yeah, the middle ones better
46:22 Right. Give or take half of . Part of it is because you
46:27 oil behind through those snap off They talk about part of that just
46:32 you bypass a whole bunch of oil have all kinds of length scales.
46:39 by the way, right, it's four system as you get bigger and
46:43 volumes run into more and more length . So it's quite easy. Uh
46:49 when we produce, we, we wells in the Gulf, we have
46:54 tags in the casing, we would some of the tags come together,
46:59 tags come apart. Then you look later, these tags that were actually
47:03 apart, you'd come back together, once it, but you produce reservoirs
47:13 a very non uniform way. Probably familiar with that already. We're OK
47:21 how we do it. Now, gonna go through a hypothetical problem.
47:26 going to uh show you basically uh we uh basic idea behind using
47:39 And I'm gonna tell you enough, enough to make you really dangerous.
47:44 Then we'll spend most of the rest this course kind of getting a better
47:49 of how to actually get more right? I I thought it was
47:56 actually just go through the kind of scheme, how do you use reactivity
48:01 calculate evaluate parameters? We will do called a quick look exercise. We
48:09 enough tools to do this and actually of go through getting, using just
48:15 to get the parameters and Archie All right. So what are we
48:22 do? This is basically, I the order we're gonna go in,
48:27 , we will uh detect permeable What we mean is reservoir versus non
48:35 I don't mean you can use the ray to tell this formation is 10.67
48:43 ? Or no, it will tell , is it a possible reservoir or
48:50 a possible, we need to be to tell shales from sand sort thing
48:56 the gamma, right? Tell right? They won't tell us any
49:00 from SP is, is why spontaneous law. But that stands for,
49:09 ? And then a resistivity log uh gonna look at two Dutch or la
49:16 common in use. And then how we give choosy? We have three
49:21 velocity logs, density neutron acoustic kind in order of increasing f complexity to
49:28 in that direction. And so, we'll talk about how they make the
49:33 , right? What exactly they're Uh How do we interpret them in
49:38 of velocity main difference here, I use resistivity to saturations. And why
49:45 that? Because oil doesn't conduct, , what these logs measure is approximately
49:51 same for oil and water. So cannot be used quantitatively to get a
49:58 from. Yeah. So what they you is basically how much rock versus
50:06 space you have. It's actually probably good thing. And so we need
50:12 , we need to determine where are , our producing zones and then
50:17 right? Money. Everybody understand what set to do here. What we
50:23 do. How often do we take for an hour in? I like
50:35 go an hour and a half. shorter breaks maybe get out a little
50:40 . I I find that people's attention don't go much past an hour and
50:44 half. So, but I can , push you for an hour and
50:48 half. All right. OK. what other methods can we use to
50:57 producing zones? Saturations just did an last Saturday. Why did we call
51:12 all kinds of ideas for a midterm ? Saturation hide modeling that allowed us
51:20 get volumes, right? So cuttings and tests just to locate where oil
51:28 . Uh we didn't spend a long on mudd logging, but one of
51:32 main uses one of, in my opinion, just because the quality of
51:36 rock you get is so bad, post, right? Uh Bits went
51:42 and all we have is P Bits, right? We looked at
51:46 grinding the stuff with dust, but still can see oil in the
51:51 right? So you still can see as long as you're sure it's
51:56 you know, uh it's not type or something like that. This is
52:00 exciting stuff. There is some oil , right? So that's actually quite
52:06 . A lot of the reason people mud wine still, it, it's
52:11 so tough to get actual real quantitative out of cutting, people still will
52:16 to sell you that stuff. you know, enough to ask them
52:19 right questions at this point. It's of the reasons we went through.
52:25 the quality of the core and the types of corn? And then this
52:32 the cap of pressure curves. This what I was referring to saturation Hyde
52:36 by the way, these things that up in orange are tension. People
52:41 complaining you're not supposed to have this your notes, sometimes they sneak
52:47 but you're supposed to take the notes least, right? I went through
52:53 diatribe about learning the three techniques you . One of them is writing,
53:00 ? I know I show my age back in the good old days,
53:03 didn't even have power points, We had to write everything down.
53:09 what other we can use cuttings, could use cores we can use and
53:13 I would include in this kind of animal you can get. So here
53:22 an idealized log set. So what means usually to get to this
53:27 this would be, for example, , OK. So it wouldn't be
53:32 , wouldn't be a measurement from an log. We would actually use these
53:37 logs to get to our team. that would be our team velocity would
53:43 . This would mean that we basically whatever knowledge we had to exclude lithic
53:50 or whether it's a limestone dola or will affect the ferocity logs. So
53:55 have gone through the trouble to remove effects and we have what we think
54:00 a real lithen process and I would here and here is just Rezo versus
54:10 what we need like this gamma ray , right? Nor sp do not
54:16 you what the permeability is but who you they can tell you that is
54:22 to you, right? So understand data we have. So we have
54:29 permeability indicator resistivity porosity through these three . So these are my porosity
54:37 So first thing we want to talk and pick one of the exercises how
54:42 gonna do in class is the zoning squaring that isn't printed out. We
54:48 to print it out. I think should be. So we're gonna do
54:51 together because there seems to be some about zoning and squaring. So what
54:57 I mean by that? There are big rules for this that we will
55:03 through All right. And uh one them, we're gonna try to pick
55:08 boundaries here, right. So where we pick those bed boundaries is at
55:14 points on the log? So you the slope basically increasing and then it
55:22 when that second derivative is zero, called an inflection point. And that
55:27 the bed boundary for all logs that are picked at inflection points that just
55:36 to do, draw a picture here you want. But why that is
55:43 I in it better? Not very at this. And so we have
56:02 borehole, I something a borehole that a pretty accurate. And I
56:13 I have a bad balance here right . Now, I have a logging
56:21 here on wire line initially started down . This is my tool.
56:30 The tool has a certain sensitivity to as we pull this up hole as
56:36 approach this bed boundary to get up here, my tool response is gonna
56:41 to pick up, right. So will start to get a response and
56:45 pick the tool up a little And what's gonna happen here is I
56:51 my maximum, right? I I reached the point where as my tool
56:57 up, my tool response will actually increasing and its sensitivity will be
57:05 And so that will be as we pick this one, we will be
57:10 when I'm at this, when I'm what's gonna happen is my rate of
57:14 will still increase as I pull my up further, but it will increase
57:20 slowly because I already a part of tool there. And once I am
57:24 in the bed, it doesn't change . So this is all about as
57:30 approach that boundary, my tool response get to that boundary will get bigger
57:35 bigger. When I'm centered on it will no longer my rate of
57:40 will now go to zero and my of increase will actually now get smaller
57:45 smaller. OK. So always, for every tool we talk about
57:53 this bed boundary is at that OK. Pretty easy to remember
58:04 And um must have gone more by that one, that one change back
58:30 my other point. Next rule is is lumpers or splitters. There's some
58:46 of flexibility here but you, you , you use the logs that affect
58:55 calculation to pick your bed bound. so I'm using Archie's equation,
59:01 I'm gonna use resistivity. I'm gonna velocity. Would I use my permeability
59:08 ? No, because they don't, don't go into the calculation. These
59:13 all gonna be off depth a little . So I have enough compromises to
59:18 , I would pick my bed boundary on these two, I would not
59:22 my gamma away, fair enough and kind of one of the sections of
59:31 . But, but you actually, pick your bed boundaries where it affects
59:36 calculation. So that means for let's indicate, yeah, but
59:43 when something changes, right? So would pick a bed boundary here.
59:48 have to pick a bed boundary here my resistivity is changing and I have
59:53 pick a bed boundary here to go to the and the broken. So
60:22 would pick a bed boundary at the of inflection here. I would do
60:27 best and sometimes to compromise here, would have to pick a bed boundary
60:33 . Yeah, even though this one changing because my calculation will change,
60:40 have to pick a bed boundary there I have to pick the exact boundary
60:46 , right? But my porosity changed though my resistivity really didn't.
60:52 So everywhere my calculation changes, I to take the bed boundary. This
60:57 here, one here, I would one here, one here. So
61:13 can see he's already been labeled, have zone abc and indeed,
61:24 everybody see how I got those and have it with zoning. That's the
61:29 part two little associated with it and the squaring part. OK?
61:35 what do you mean by that is value do I get? OK.
61:43 always pick it and the maximum development the law. So I would do
61:48 there there just that I would go there that year. I was here
62:04 . Yeah. Yeah. Yeah. , it was meant to be a
62:15 line here, right? So at maximum development of the log in either
62:23 , what the tool is reading at points. Uh why do we pick
62:27 maximum development of the log? Because the closest to the correct answer,
62:38 bed may be thin enough. And would be a good example up
62:43 right? This would be a good that the true value may be out
62:52 somewhere because with a fairly thin but I then I'm gonna make a
62:58 what's called a thin bed correction for that would be based on the thickness
63:03 , of the, of the And what my maximum development of the
63:07 would tell me how to shift that this class. And I could go
63:12 that level of analyze the blog a of times it's done automatically for you
63:18 you're using log, whatever, but pick the maximum development log. It's
63:24 closest to the rating. So the rules are collection points only, only
63:34 bed boundaries where it affects your calculation then maximum development of block, not
63:40 hard, you know, I could this, but you notice this was
63:46 involved at all. But gamma ray a little bit different by the
63:51 because gamma ray, this doesn't look a gamma ray. The gamma ray
63:55 statistically has so much statistics in it you actually don't pick it at the
64:01 development. But you average over the gamma ray is the only tool that
64:05 you would do that. There's a and I'll talk about it again when
64:10 specifically talk about gambling. Right? why you calling me a liar?
64:24 our, so our zero, we , we don't know yet because what
64:31 are picking is our tea and, RT is only equal to R
64:37 If there's no oil, we're all ? With what we did, how
64:45 zoned and squared the log and we do an exercise in class, you
64:51 , I wander around and in a log, it might be a little
64:54 confusing. All right, what's How do we evaluate this?
65:09 And it's just right, just pointing my reservoir indicator, my resistivity
65:15 right? I use this log, is here and I brought you
65:21 All right. So if we look this, where is our possible reservoir
65:30 we'll go through this in more the principle that this is the either
65:35 gamma ray or SP it's designed to this way. But this would be
65:39 gamma ray, low gamma ray. this would be shale sand,
65:44 sand, shale sand, right? that would be, and you're probably
65:50 with that. This SP is plotted the same way even though they scales
65:57 to make it look like. So we'll just assume it's a
66:03 So it's clear where, right. roughly agrees with our zone here where
66:08 sands are led, right? So have basically 1234 zones that we're gonna
66:15 to value. Yeah. How would do it? What would you
66:24 You're experts on saturation pipe modeling, ? I have here. I have
66:32 constant porosity, give or take my is changing. Why, what would
66:38 your guess as saturation height models? sorry, what? Absolutely. That's
66:49 , we're actually we've been either lucky or unlucky enough to encounter a transition
66:55 , right? So we move down on the cab curve, our water
66:59 picks up as we move down. my resistivity drops. Yeah. So
67:06 would, for example, my my displacement pressure would be, where would
67:11 100% water level be? So I have 100% water up to here.
67:21 would be my entry pressure for my curve. My oil saturation would be
67:26 up here, right? And this that boundary basically averaging in the
67:31 right? So my actual volume, it would be based on a squared
67:37 . But since you're saturation height can you see the power at combining
67:43 two techniques? Right? This is idea you're really going to call yourself
67:49 who evaluates formation, right? And just a log analyst. So there's
67:55 wrong with being a log analyst, ? But the power is tremendous power
68:00 combining those two techniques and the insight give you as to what's going on
68:05 a rear. So what does that ? I can do if I know
68:08 is 100% water saturated? Let me your question. Right. And we're
68:14 RO here and we're gonna measure RT , right? So that's the way
68:22 would start given that interpretation, So we located the can be located
68:28 ? The Perles zones, I guess can call this CS P. Didn't
68:32 noisy enough, right? We got zone of ABC and D. We
68:38 our shale boundary and then we start in our bed boundaries, which I
68:46 interestingly enough. They agreed with Yeah. So at the inflection
68:52 just like I talked about um then gonna pick our right, we're gonna
68:59 the resistivity curves. So we, have a pretty good interpretation for what
69:04 is. Yeah. However, we high resistivity here. We have low
69:10 here. Is this due to oil is this due to water? Are
69:16 things can change in Archie's equation change activity, the porosity or the
69:23 One way to think of Archie's equation it allows you to quantitatively differentiate velocity
69:32 from saturation change. So you can what happened. My porosity dropped uh
69:40 this zone that's gonna cause my resistivity increase, but there still could be
69:46 there. Huh? So we don't . So this is the main thing
69:53 gonna figure out down here. I have the same porosity as
69:58 but a much lower resistivity than So, again, I would talk
70:02 the geologist, right? Is this the same ology as this geologist is
70:08 tell me, I guess. So that gives me a pretty strong
70:13 to interpret. This is G and resistivity is the same as Peter,
70:18 ? That gives me a real clue to what's going on here,
70:21 Because of water saturated, plus, way below what I think my transitions
70:27 , is it possible to have oil water? You could have a barrier
70:38 between the two, a separate source charging to the two. So you
70:43 indeed have oil. It happens all time. It's called called perch water
70:48 . OK. Uh You could have above oil saturation. So miss a
70:55 of oil if I, if you're aware of that, right? But
70:59 still don't know what this is, ? We can make guesses about
71:04 this particular if I've cut a core all of this. And I have
71:08 idea right? Of what the rocks or even if I had side walls
71:13 even cutting nail, I think this looks a lot like this. That
71:17 be a big clue. So I would ask, well, why is
71:22 ferocity changing right? From this 30% I would ask the geologist,
71:29 That would give me a good idea the ferocity can handle it or whether
71:33 need an oil saturation change too to that increase this resistivity is higher than
71:41 . So if you were just basing on the, on the activity log
71:46 would complete this. Right? If had no other information that happens quite
71:52 bit more often, it should, don't run ferocity on when they do
72:00 . They are claiming they understand what changes quite well. All right.
72:06 we're OK on what we're gonna try do. So up here at the
72:11 where we square right at the max development, then we want to differentiate
72:19 from porosity chain, saturation chain. where we don't know exactly is here
72:27 a zone A versus C. So gonna calculate water saturations to figure that
72:33 , right? So we're gonna calculate zone a his own and squared
72:41 And I can't draw lines that and notice here, people complain about
72:46 It's obviously not at the inflection but table stretch, things like
72:53 All of these are detailed you get with, right? Your tool sticks
72:57 little bit, you stretch the you do your best, put everything
73:01 for that, things like that, everything on depth. But probably the
73:06 of the time you spend saturation, the reservoirs about getting the logs on
73:13 and correcting for things like that. deep, you know, if you
73:19 fun. So how would we do ? I guess we're gonna use uh
73:24 equals N equals two. Don't need know it's here, but we can
73:28 Archie's equation. We're gonna assume that water contact green zones A and
73:34 Just like we talked about, we're saturation height modelers and it makes a
73:38 of sense. Right. Ask the , they don't see a lithograph change
73:44 . So I get them on board really good reason to be talking to
73:47 geologist because then when you get it , you both could be blamed,
73:52 ? It's not just you sticking your out all by yourself, right?
73:57 good a reason as any get as people involved, right? All
74:02 So we go ahead and do that of the batteries. Yeah, somebody
74:08 me it was relatively shay and very calculation. I send all my properties
74:13 the same thing. He uh can take the square root of the relativity
74:18 . And that's like magic, Simply take the square root of the
74:24 the ratio of those resistivity. Given assumption the li is the same and
74:30 pops the saturation. What could be than that? What assumptions that we
74:42 my porosity was constant, which is good. We got that from the
74:46 . We did assume the m was . That's why I talked to the
74:50 did that all cancel out and then was equal to two. That's the
74:56 root I have in the calculation is to that. And then RW didn't
75:01 . It is not uncommon for particularly you have a significant depth change.
75:08 not uncommon for RW to go down go increasing depth. So sometimes you're
75:15 to include that in the calculation a of times you don't have enough data
75:20 do that, right. So we OK with what we did, this
75:28 pretty easy, right? This would us a saturation that gee if we
75:33 some idea what the cap curve we could validate what the saturation we
75:38 getting. This would give us an in some sense, particularly here because
75:44 are in a transition zone, we know where the we would know where
75:48 100% water level is. If we a cap curve, that would give
75:52 an idea where the free water level . And so we could start to
75:56 by combining this, we could start build a saturation height model along with
76:02 , that we have an idea here move it to the next weld or
76:06 either moving up or down on the , what's gonna happen to us.
76:10 at least we would have an ability predict as we moved away from that
76:14 weld. Yeah. Starts to get powerful, I would say cool.
76:24 right. Now, zone C like mentioned, we can't do this but
76:30 is a pretty good thought that when we go, like I mentioned
76:34 here, this looks a lot like . I resistivity is quite a bit
76:39 . So, and, and comparable here. So I have a pretty
76:44 idea that should allow me right? get using that, that value
76:50 Ferocity to get an RW that should me to calculate what's going on
76:54 Right. My RW is the same is here and it's pretty good.
76:59 , it's the same. Yeah. so that's what we would do.
77:07 the C right. So we could a saturation simply by taking the ratio
77:13 the RW, we calculate right. my RT I measure there and I
77:19 RWII I could solve this. I'm , we you could solve this for
77:23 RW is if I know what my saturation is that is one. So
77:34 you have to do that at the temperature. But for zone C I
77:40 go through and calculate what my, what zone C was that high
77:45 low porosity spike at 7% porosity right? C I would say
77:52 then you can calculate this, you're get a water saturation of one.
77:56 the resistivity in that zone is fully for by the porosity change. Then
78:05 I use that RW that I calculated ? And I could directly calculate a
78:10 Archie's equation and I get close enough Petros right to the same number.
78:17 that a reasonable residual water saturation? gives me another idea about my cap
78:25 . Right. What my residual water is I find the cap curve.
78:31 . So I have a pretty good . I have my 100% water
78:35 So I have my entry pressure, have my residual water saturation. I
78:39 my other half and coat and then have some idea based on the
78:43 what the sorting is, porosity is good. But I can make a
78:47 good guess on the shape of the cap and where my, where my
78:53 water level is. I would ever it a pretty good idea because I
78:57 a transition zone to model and then can do volumes just like we could
79:04 the volumes before. Yeah, and could get economics, right? So
79:10 equations we generated last time, what number of barrels of oil are given
79:18 section. And sometimes when I've given lecture that's been pretty high compared to
79:23 the price of oil is. Good is. It's fairly low for
79:27 right? So you can calculate whether should, if it was gas,
79:33 would go to the separate calculation, worth a lot less by the way
79:38 gas. So this is uh we'll a break after this. So this
79:43 the final thing that I want to . We talk about this a little
79:47 . What we did, we assumed knew the resistivity out here,
79:52 Uh And we assumed we knew the here. And so all of this
79:57 complex situation, right? We somehow have to figure out and we're gonna
80:03 a fair amount of time through the of the course, trying to determine
80:07 the diameter of evasion is, what blush zone resistivity is or could even
80:13 a stab at what the blush blush saturation is and then what the diameter
80:18 evasion is, right? We're gonna mud cake thickness and things like
80:23 So some of this is notation you see an X in it means
80:27 flush zone. So Sxorxo, it's zone, uh resistivity of the mud
80:34 is gonna matter some cases. Uh just that correction, as I mentioned
80:39 little bit, we really need to RT, we really need to get
80:44 we really wanna calculate SW. So where we are. So basic idea
80:51 that kind of the thought process you through and you evaluate a reservoir and
80:57 uh I don't know whether this excites or not, but a lot of
81:00 rest of the course is about filling some of the detail. And how
81:03 I really get the right numbers to go through this thought process? What
81:10 be more fun? Right? I we're done. It's time to take
81:24 break, saturation height model. Oh gonna go ahead and do that
81:38 It wasn't a bad idea to do in the order. We did it
81:41 . It, given what I'm gonna . So, we have a hypothetical
81:46 here. We're gonna drill uh five . Um We're gonna look at the
81:52 of this. Well, so the wall is much like that first.
81:58 , we found we have oil, have a transition zone and we have
82:02 water like at least the top of , right? So you drill this
82:05 , everybody's all excited, right? all excited. You have a
82:09 you have oil saturation, right? your boss comes to you and
82:13 well, gee what are my What do you expect? And based
82:18 talking to the geologist, right? understand the structure and the geophysicist,
82:24 understand where on the structure you you understand, saw the free water
82:28 , which is here cursing you you have once reminded and show the
82:38 . So we, we have a water level here, right? We
82:41 100% water level here and then we a critical water saturation here. So
82:47 only bring the oil up here and is what we got. So we're
82:51 excited, right? You know, fairly low on the structure. So
82:54 boss says, gee uh should I this other well up dip? You're
82:58 find any more oil. And what you say? Expert saturation height
83:06 What do you do? How do make that decision? Come on.
83:15 the geologist, you're the one you're go to. You're the one who
83:18 to answer this question. Should I this next? Well, gonna move
83:28 here. I, I found oil . I found the transition zone here
83:36 I'm gonna drill this well, of structure. You're the geologist. You
83:47 it's a fairly homogeneous reservoir? Well, yeah, sure. I'm
83:54 drill anywhere. I'm gonna drill So that's what you'd say.
83:57 Ok. The guy said great. let's drill it. We invest the
84:01 million to drill it, lo and , you were right. Right.
84:04 , all kinds of money moved up life is good, making it.
84:08 he said, should I keep going up yet? What questions do you
84:16 a geologist to answer the question? do you say? I need to
84:21 ? Yeah. What's the structure? . But my depositional setting,
84:28 I would want to know. Well. Right. Are we gonna
84:35 into the, are we gonna run the, our seal? For
84:40 where are we? Is that what said? Yeah, sure. We
84:46 want to penetrate the gas pump. would be a bad idea.
84:50 Again, producing gas, all we is blow down the reservoir, uh
84:55 a lot of money. Ok. your answer is, yeah, we're
84:59 from the gas cap, right? gas cap, et cetera. So
85:05 go ahead and drill the well, do we find water everywhere?
85:16 what do you do now? He , gee, I lost a lot
85:22 almony on his lab. Well, . Can you do this to me
85:25 or are we looking for a new ? You know? So what do
85:29 , what, what do you ask anything? Just roll the dice.
85:39 did you do wrong? According to elementary saturation I modeling, this shouldn't
85:47 happened to you, right? But could have been possibility this perch water
85:53 we talked about before? One What other possibilities would there be that
86:00 happened to you? What are you guess? He needs an answer,
86:12 ? He says, I need the today. I got a drilling schedule
86:17 you, right? Look for a job. So you, you would
86:31 your best to answer a lot of geologic questions we've already asked,
86:35 So what are the possibilities? How went wrong once you got a different
86:40 ? You're on a different chapter, ? The possibility, right? So
86:44 kind of rock would this, would have been more permeable or less permeable
86:49 ? You random thing? I would asking for somebody to go into
86:57 Well, for example, and shoot sidewalks and think, right? So
87:01 have some idea what happened to right? You need more data.
87:05 first thing I would say to right? So our understanding of our
87:10 of something was not where it needed be. This cost us a lot
87:14 money. So gee we need to , we need to understand the geology
87:19 lot better. So, so you in and you shoot some percussion
87:23 what might you find the questions are good enough to answer the question.
87:29 might you find, what would cause , how would your cap curve have
87:41 ? For example, if you had much higher entry pressure, right?
87:46 displacement pressure, your 100% water level a lot higher. If you had
87:50 tighter rock, right, then you have enough column height here to get
87:54 this rock, whereas you would have better rock down hole. So
87:59 we had been shooting percussion side walls here, a view of them or
88:05 examining cuttings where we could get them to have some idea what our rock
88:10 , some idea what our grain site , right? And then we went
88:14 here and we found, gee we we had a much more cemented,
88:18 ? Much more cemented. Li we tell that from our drilling rates,
88:22 kinds of things could enter into So I'd be looking into all that
88:26 of data, right? Did my change. And so what you find
88:31 that the rock type did change, was tighter, it was more
88:36 Yeah. So then what are you say? And I'm still not near
88:40 top of the structure. I don't I'm near a gas cap like you
88:45 . But what are you gonna Probably you drill it, right.
88:52 , everything looks like g particularly. what do you find? You find
88:57 but oil there, right? Everything good. And you're a hero
89:01 right. Made a lot of You drill a well too.
89:06 This is where right there is an . So the whole point is clearly
89:12 have to study our cap curve a better or you'd be able to answer
89:16 of these questions. I was asking , what question do I need to
89:20 ? What do I need to The big thing you did? Ferocity
89:24 changed as well. Maybe you didn't run any ferocity lot here. You
89:29 feeling so good about yourself, So I I would have gone in
89:34 once you found this and tried to out why what happened, what changed
89:39 between here and here. Why did ferocity change and why did my rocks
89:46 ? What happened cause that? And then this, this for example,
89:50 have been some sort of locally cemented , right? Or something like
89:55 that you would struggle to understand, ? Or even a sorting change,
90:00 ? Happened here. Such of my pressure was a lot higher here and
90:04 in the transition zone. So we right? There is some oil
90:08 right? That's what the purple Right. We're in the transition
90:12 But so a sorting change could have . It changed here. Right.
90:17 have been that we had penetrated a sand here that we expected it to
90:22 fairly local. We got it here this is like over bank or
90:26 right. Lots of clay, And we figure, right, depending
90:31 where we are or right on the , et cetera might lead you to
90:37 to understand, right? What would if I move further up again?
90:41 . So all of the geology is gives me information on this length scale
90:46 why I like talking to geologists. the ones with the answer on this
90:51 scale. You know, that was main thing I wanted to talk
90:57 So here's just a picture of what happened. Yeah. Had some other
91:03 type, right? And he drove , well, it was a poor
91:10 and again, there's a relationship between of these, once you understand this
91:15 spend some time with these curves, cap curves, understanding how cap curves
91:20 to permeability, how they relate to saturation and the relationship between porosity changes
91:28 how that impacts cap curves. All those things tie in with each
91:33 So it s you to put that together, right? Where am I
91:39 my oil i entering the corners of or building new poor systems, et
91:44 . But I'm doing all of that might have even more. And then
91:53 is a point I guess I haven't this class, but I think this
91:57 quite an important point. If I at this porosity versus permeability, uh
92:03 steep are these curves? Notice this a log scale, typical uncertainty bros
92:09 , maybe, you know, I know, five pu units. That's
92:13 possible if I'm moving that far, far up and down the permeability might
92:17 go? How good a predictor is for permeability? People correlate it all
92:26 time that you'd better be awfully sure what you're doing given that level of
92:32 . That's why permeability you struggle with in every red, right? How
92:37 I predict permeability? It's because he out R squared, it goes like
92:44 of the fourth where the dependence of flow and two. So these
92:49 you've got that going on as well you have changes in tortuosity, possibly
92:55 quite easily to get 34 orders of firm. But then a vero happens
93:00 the time. These are not So your predictive capability vero is like
93:09 why? That's why we'll talk about because curves are typically that speed.
93:15 another example of that and this, is even what makes your life even
93:21 miserable is even such things as clay can have a huge impact on.
93:27 show you these already. So what this is meant to be is we
93:34 four bridging plays here. And I you, I think fibril lights,
93:39 would be an example of that or claves grow the top floor space.
93:44 would be core lining clays like a coating of the four walls. And
93:50 this would be structural clays. So structure plays hardly impact permeability, get
93:57 blown, we line it with we have a lot of ineffective velocity
94:02 permeability. And for bridging clay is gonna end your world. So this
94:07 why it's so important to understand what of clay you have, how much
94:11 you have, right? Uh what distribution to understand for bridge and clay
94:17 aiming to be, by the it's really easy when you make a
94:21 measurement to play those against the So people do what's called a critical
94:26 trying related to that or even just distribution. This was uh this was
94:33 relationship, this is a mere parameter . So, again, water saturation
94:39 porosity, it may just be following is basically the infinity. So this
94:47 follow a chapter that's just the idea a transition. So for example,
94:53 I have a sword and change or like that, I may be moving
94:57 effectively with a cap that curve looks . We talked about that the importance
95:05 looking at rocks again related to So we, we have basically doesn't
95:10 like a very good correlation here, much predictability between porosity and water
95:17 But G if, if I look the lithograph, one of these is
95:20 carbonate, the other is a plastic G I might be able to separate
95:25 , I might be able to get information from a log. So I
95:29 might be able to do by looking the rocks to be able to get
95:32 much better idea of what's going on rest for exaggeration. Again, water
95:40 versus per. So it's cool. makes sense. But as, as
95:46 , as my water saturation goes my permeability is going down. This
95:51 the dry air permeability. Why would water saturation go up? As my
95:57 went down in a water wet Where's the water wanna be in a
96:10 wet rock? It wants to be the small borders, more higher surface
96:14 , higher adhesion tension. So it's reasonable that as my, as my
96:21 went down, my pores get So my water saturation go up a
96:31 example. And then this one will about it. It's about the
96:36 You're not really, it didn't go the NMR, but we're gonna spend
96:39 time on the play. Don't worry that one that worth going through.
96:51 is the end of the last, was the last election. It was
96:54 end of it. It didn't go the end of it. We quit
96:59 you knew enough to do the And the idea is once you've done
97:04 exercise, you have a better feel saturation pipe bottling. So to kind
97:09 wrap up some of these conclusions, more sense to do after you've done
97:14 exercise, he wasn't feeling very Problem is I lost part of my
98:10 . Yeah. All right. So wrapped up saturation height modeling. Now
98:17 gonna go through permeable zone logs and uh we have the uh I think
98:25 the last lecture and then we have exercise we'll do at the end of
98:29 just about zoning and squaring logs end in sight. All right. So
98:54 s own logs and that's a bit a misnomer. It does not tell
98:59 the permeability fact. Sometimes it's a reservoir will be high gamma ray,
99:07 example, that's not unusual at all carbonates. So, uh we're gonna
99:14 through what we actually mean by this permeable zone logs better would be reservoir
99:21 logs, right? And that's gonna the SP and the gamma ray.
99:25 use those to pick out reservoirs, ? So it's the SP which is
99:32 electric log, a bit of an thing, quite a simple log.
99:38 And then the gaming almost always, presented in to the left of your
99:44 presentation. And then uh we will uh like all the tools we're gonna
99:49 about the physics of the tool interaction the hole, how we tell how
99:54 interpret our formations and then what the of surrounding zone is. And so
100:01 a look and see the statistics in gamma ray, right. Here's my
100:06 which doesn't have nearly the statistics. is why the exception to that rule
100:11 excellent development of the log one is are statistical on a gamma ray.
100:17 typically wouldn't make separate zones for each the right. The statistics you would
100:23 one line through the middle of it at the peak valley, right?
100:29 at most, you'd have two zones you had some other reasons, if
100:33 were, if you were going to sometimes the gamma ray goes into your
100:39 evaluation, particularly if you're doing like analysis or something like that, then
100:45 might want to include that in your , right? If you're not using
100:49 in your calculation don't zone based on . OK. With the gamma ray
100:54 that they basically this is high gamma , this is low, whereas this
101:00 high development of ESP this is low . So they deliberately flip those,
101:05 look like each other. Yeah. . Then we have our resistivity.
101:10 think it's somewhat clear, right? could see my right. Uh my
101:17 gamma ray is where my sands right. Have shale and sand sp
101:25 actually following fairly well talk about the of all these first thing we always
101:33 is draw in my shale baseline. , first line, I typically draw
101:39 can be tilted by the way, not unusual at all for my shas
101:43 get hotter if you go deeper in , if it's really a fairly large
101:48 interval. All right, that allows to differentiate right. Shale,
101:54 right, embedded, sand or a , fairly embedded, maybe, maybe
102:02 here. An A P really doesn't up much of this law, but
102:08 just wanna know San from shale, a basic my shale baseline on
102:19 So they are used to distinguish, , sometimes to distinguish uh shale from
102:25 shale. A lot of times they track each other. If you're
102:31 one of them will work and they related. Both of them respond to
102:36 clays. What happens is as you clays, the gamma ray will pick
102:42 , right. Typically the clays are than the sand, almost always.
102:47 VSP is actually suppressed by play by charges associated with the and SP you
102:57 use it. Uh You're making a of assumptions. It's not the best
103:01 to get an RW, but at it can give you some ballpark and
103:07 , we'll go through that calculation. first one we're gonna talk about is
103:12 SP it records a difference in the potential. So that's a voltage right
103:19 a fixed electrode at the surface or and then we just pull an electrode
103:25 the bore. This one's easy Right. I don't have a lot
103:29 geometry clearly. You have to have conductive. So, for example,
103:34 the Gulf we used to get SPS the time. We switched to
103:39 uh, to an oil based Don't get SPS anymore. Still get
103:45 . Right. It's scaled in millivolts does. It's in mili volts that
103:51 can drift quite a bit. You're just putting a shale baseline on it
103:55 and then measuring relative to that shale . Yeah. So there is no
104:01 . They're only looking for differences between it develops and where it. So
104:09 an example and a look, there several mechanisms. So this is the
104:15 behind the tool. We have an , we're pulling up the borehole,
104:19 ? It's relative, we're just measuring potential. It literally is just a
104:25 potential development being this electrode in the that we are choosing not to that
104:34 down. So the SP develops an like I say and increased amplitude is
104:41 game out of it. And then have a static sp and just the
104:47 measure and static sp is presumptive value would get in the absence of any
104:56 minerals. What happens is clay minerals the amplitude of this because claves have
105:04 negative charge which I think I mentioned this blast. That means the chloro
105:09 don't get through the this first play well through the clave very well.
105:14 you don't fully develop the sp. first rule of year um for the
105:22 is what does it measure and what measures my shield baseline. What it
105:28 is a salinity contrast. That's all measures, measures the salinity contrast between
105:35 mud filtrate and the formation water doesn't you an absolute measurement of RW give
105:44 a contrast between whatever my RMF is , what filtrate is and what my
105:52 water is. See how that might interesting. How do I get my
105:58 filtrate? Typically I have somebody measure if you ask them too,
106:04 Whoever the logging engineer is or the water, right? You actually ask
106:09 to measure what RMF is, will periodically and they take a sample of
106:14 mud, they put it in a and push out the water and they
106:18 them, you know what it is the surface, you know what it
106:23 at surface temperature, gonna compare a lot of measuring things and the
106:31 you need to raise the temperature. SP means it's actual reflection as in
106:37 cleanest rock. My static sp is kind of theoretical number I would get
106:43 there was no claim. So when try to attempt to measure an
106:48 I'm always doing that in my maximum SG. However, that is,
106:55 the closest to a non clay supress . So they're actually right, always
107:03 related to a salinity contrast, which what we're showing here. So this
107:08 typically gonna be uh again related, ? So the RMF versus RW,
107:14 measuring that contrast between those three gonna you the equation and you have two
107:24 of the SP one is there's a actual fluid flows next slide,
107:32 So we have high pressure, low and when I will blow if I
107:38 fluid, if I actually am for example, to the extent where
107:43 get a significant flow of ions that develop an EMF related to that.
107:50 way to think of that is if have moving charge that requires an EMF
107:57 move that charge, if I'm actually a brine flowing charge, so that
108:03 develop a voltage that's related to the . That's not what we want to
108:10 . We want to measure a salinity . I might be able to get
108:16 RW we pick our bed boundary on points like always, right? Just
108:25 to geometries like be that not And so we have a boundary
108:31 That definition, it's gonna vary with formation properties, my mud properties.
108:36 used to select permeable zones or my zones. If we're lucky, we
108:42 our w and if we're in the , I can actually get from this
108:50 , we also make similar measurements in laboratory. It it's called uh electrochemical
108:58 , right? So what we do we take a core plug. We
109:02 one salinity past one end, we a different salinity. Past the other
109:07 , we generate a salinity contrast in sample. OK. And I know
109:13 what my salinity are. So I what potential I should develop. It's
109:18 than that. So that tells me Shali is the way that works.
109:24 I haven't had very good luck, the way, with that measurement.
109:28 fact, I had one, I one master's student quit that because he
109:33 get it to work. Right. even took him to shell and we
109:37 their existing equipment but never got it work. He went to get a
109:42 in another department. Maybe he was . Um But uh so I would
109:49 , I'm not sure even everybody does makes those measurements for you. I
109:55 it shell like it for a long . So that's about getting RWRW is
110:03 . I have never seen anybody attempt get shass in a bore. Too
110:09 uncertainty. You never know what RW . You might have a reasonable idea
110:14 RF is the, you have to those precisely because you're looking at a
110:19 millivolts at most suppression. Welcome to it. Any of you ever get
110:28 to work? I'd love to hear it. Yeah. So like I
110:34 , there's four sources of this, electro kinetics. Again, we're not
110:39 worry about, but if you are , uh fluid. If you
110:44 if you have fluid losses at rates enough that these would impact you,
110:48 you have bigger problems than determining, , what RW is, you need
110:54 walnut shell or something like that. , uh I, I, I've
110:58 seen anybody attempt this either. This another thing that people have done in
111:01 lab. They will actually flow fluids measure a potential development, but I've
111:07 seen it used for anything useful. can write papers based on it.
111:12 we have two of these called membrane , which is the one I talked
111:16 measuring the lab. Then we have uh liquid liquid jun pen a little
111:23 different. So we have two sorts those. There are the electro connect
111:28 can be cancel with each other. I just wouldn't worry about the data
111:32 the purposes of this story. So shale is a membrane right potential.
111:39 due to the passage of sodium non of chlorine. And so uh again
111:45 it because chlorine don't like the negative in the clay. So it will
111:51 , you know, it inhibits passage the chlorine. That's why you don't
111:55 a full development of ESP it relates the ionic activities. This is why
112:03 add the eat. Still remind of . So that's why we have the
112:13 here rather than just RMF and And we have a chart go between
112:19 right and R at show you that in a second, right? So
112:24 you look at this, this is response equation. What do you see
112:28 it? You see a saturation, don't see a reactivity of the mud
112:38 and I see it done then I saturation with this tool. No,
112:47 not respond to that. It doesn't to permeability, doesn't respond to relative
112:53 . It responds to the ability to ions and the potential that's generated because
113:00 that, if you're moving ions, ? So you have a high
113:04 old concentration ions are gonna move, generates an emmemm those ions right?
113:13 a demand, right? So you have a coefficient here of the log
113:18 ratio. What happens if RMF is than RW? This number will be
113:27 ? What happens if RMF is less RW? This number is negative?
113:33 you will get different deflections depending on your RMF is greater than or less
113:42 the reason your formation water activity if this works, it's a great
113:47 RW pretty hard to get. So , when you get asked on the
113:53 , there's no midterm and you get on the final, what is this
113:57 measure? You're going to say a contrast between RMF and RW. You're
114:08 . It's ionic activity that's directly related the, basically the same thing.
114:19 sorry. What? Which passage? This is, this is your,
114:28 , it's the membrane, this is the tool makes one of the
114:34 the dual managers, that's the response the shale. This is my liquid
114:40 junction that takes the same form and just a different coefficient. And so
114:45 just have to add these two So that's the next slide,
114:50 So this is across a boundary in field train. So the whole thing
114:57 end up with A K. So E right, my electrochemical potential e
115:04 is my total tool responses to some those two earlier responses, right?
115:09 this K is temperature dependent. And , there's just these this ratio of
115:16 two effective reasons given they just done . And these filtration potentials, I
115:26 want to spend much time on because don't use, they tend to cancel
115:31 ? Small, right? They are . So almost everybody ignores them,
115:36 ? And if you have these kind problems, it's usually this tool
115:42 interpreting the detail of this still like I said, the least of
115:47 problems. So this is my static response that I already mentioned and we
116:08 use this to drive RW for my SP response and knowing what our MF
116:18 , how do we do this? is uh I think your homework problem
116:22 to go ahead and do this. go through and explain what to
116:27 Oh, thanks. So what you is you're, you're at the
116:33 your RMF is measured at the right? So you're at some
116:38 ambient temperature. So in order to the tool response, you have to
116:43 that RMF to the bottom hole temperature you, wherever you want interpret the
116:49 . So then that gives you what RRMF is at in the subsurface I
116:55 then go in, I have to through an activity chart that I'll show
117:00 in a minute to get that What that rmfe is, then I
117:07 calculate what our we is from the of the static SP. And then
117:13 have to take that typically, if want RW in the subsurface not
117:18 If I wanna know what RW would at the surface, then I would
117:21 the temperature correct attitude. I'm I'm gonna show you how to do
117:25 one of the last slides. So fairly straightforward and it's worth the
117:30 right? So what is the sp over a long fresh mud look
117:36 So where's my, where's my water to be the freshest? And I
117:41 how salinity typically will increase with Um So very fresh water at the
117:50 we're gonna have RMF equals RW. my tool response gonna be there?
117:58 the log of the ratio of those blog of one is zero. So
118:06 get no, the black. And then here where I'm pressure,
118:11 gonna get collection in one direction where more saline. I'm gonna get a
118:16 uh opposite direction deflection. And I'm get the largest deflection at, let's
118:24 if I was right. So here deflects to the right. That's because
118:29 pressure than your RMF. Here we no response. Here. Here it
118:36 the other direction here. My complexion even greater. So again, I
118:42 repeat myself. It's measuring a resistivity , not an absolute resistivity. In
118:50 to interpret it quantitatively, I have know my RM back at the
118:58 The tool is that about a saline sole or saline mud, what's gonna
119:07 ? Yeah. Precious at the RMF was getting with RW there.
119:13 where's my biggest deflection gonna be starting the bottom? Because that's where the
119:23 is. No, no response, response here. Here I get
119:31 A little fresher and up here it's fresh. My biggest reflection from the
119:36 , right? Just has to do again, the general trend is that
119:42 uh formation water gets more sailing damage already on. I've asked geologists why
119:51 is, haven't always gotten a good here, an expert on that.
120:01 does formation water get more sailing and in depth? Pretty general role.
120:10 sure. The usual answer I get that the brines had longer to interact
120:14 formation formation. So you just tend accumulate minerals with increasing depth of the
120:21 , right? And increasing concentration that the salt makes sense to me.
120:30 , here's a look at a real . OK. The draw shale baseline
120:36 . So what happened between here and that actually left being right kind of
120:47 from being uh less fresh to more than my RML. This water water
120:56 saltier than the filtrate. This water fresher. That's kind of opposite what
121:02 might expect. So, the shape the sp, so I don't know
121:12 you did this, I actually did lab like this. You, you
121:18 take a map out electric fields and had a little bars and you put
121:22 in one potential and you had a trait, you could map out constant
121:26 lines, right? It's kind of . But the whole idea of if
121:30 have some concept of what an electric line and the more resistive rocks,
121:35 tend to pull the field lines into more resistive rocks. Ok. And
121:42 what happens is in very resistive this thing gets hard to pick bed
121:49 . And if the rocks get extremely hard, another misnomer by the oil
121:56 , hard is not the same Exactly. But when that happens,
122:01 tool gets pretty tough to pick bed in perfectly. So things can get
122:07 out. So here's, here's some of that, right? You can
122:13 where it's more existing, right? you can see how the field line
122:17 gonna get pulled into the more resistive . So this, by the
122:21 is at the inflection point, even we, most of us would pick
122:26 here. What I mean by it's tough to interpret bed boundaries and
122:30 like that here. Right. Still the end of election point, et
122:34 , if they're roughly the same it looks pretty normal. And so
122:39 there are no reasons to be I don't know, most of us
122:44 so SP can have pretty, uh weird shapes. Bed boundary is always
122:52 the inflection point. Still, I'm lying to you a little red.
122:59 so at high RT RT, good unit, right? So it's not
123:03 much in hard rock. Maybe the thing about this is hard rocks are
123:09 synonymous with resistive rocks. So it's resistive rocks that confuse this thing you
123:14 don't care about physically, but it's , toughness is or whatever. And
123:26 you can get that correct charts or , but people generally will tend or
123:31 use the game. So here's an of that. It's basically a troubles
123:45 in their hours of. So how we get because I was a little
123:50 early. Uh What would I do get RW for my SP here?
123:57 portion of the curve would I Actually? Helps remember what happens as
124:08 as it becomes shali. What happens the SP it gets suppressed where I
124:17 to interpret our W from is where get the largest collection but where would
124:23 use it? Which of these zones 23 zones? Would I use this
124:29 zone? A right. So that's cleanest rock. So I would go
124:36 and use that number of millivolts. always, there's no absolute zero for
124:42 . You have to draw a shale line here and measure in millivolts
124:47 Each of each of these is 10 supposed to be. So, if
124:52 read this, it's like what, , 2030 40 50 60 millivolt,
124:58 like that because I counted wrong. . Yeah, read it wrong.
125:08 to 70. Yeah, it could what I would do. Cool.
125:15 you read the SP value from the and again, this is your homework
125:19 do a problem. You have a difference between the shale. You need
125:24 have the correct deflection. What's gonna if you have the wrong sign still
125:29 get a number out of it. gonna have it being fresh rather than
125:37 . So you've got exactly the wrong . You read RMF from the log
125:48 . This is maybe the hardest thing because somebody has to have asked the
125:56 water or whomever is there to give an RMF when you're penetrating this
126:01 right? Why you're typically asking this get an RMF as a change additives
126:08 the mud, et cetera. That's physical measurement. Again, scoop the
126:12 out of the mud. Then put in a out our the mud
126:17 you measure that resistivity got a meter the surface to do that,
126:23 OK. You read it RMF and you have it, you convert it
126:27 the temperature of the zone and the and you can move that down home
126:30 show you how to do that in second from a chart or an
126:35 So this is a generation nine or chart and then an AP equation.
126:40 thing about this tool is it's a electrode. It doesn't have a
126:45 So everybody's tool is the same, ? So any chart works from any
126:52 ? Yeah, there's no spacing or like that, right? So
126:59 with 68 mil volts minus 68 millivolts the depth we wanted our RMF,
127:05 measured was 0.171 millimeters. Our formation is 100 and 29 degrees. We're
127:11 use the Arvis equation which is simply . And so we are correcting,
127:19 ? Oh Static se was 68. is like I, I'll show you
127:31 equation a second to make sense. going from 68 to 100 and 29
127:37 that's from here to here. And this was my, uh this was
127:41 R and that I'm so we then we have to go from RM
127:49 F. We had that RMF. just changed the temperature. We now
127:54 to go because it's the activity which pointed out that's strictly a resistivity.
128:00 so we have to look up in charts with that how to correct between
128:05 and RMF. We can then plug into here. We can calculate
128:09 we, we then have to go through the chart. Get back to
128:14 w easy enough. So you can this chart to do that, just
128:22 the equations right. Then you want check that against other sources of
128:29 This is the chart you use, back and forth between RWRWB. All
128:35 do is enter with RW, go break temperature line and our government or
128:42 go the opposite way to get back our government easy enough, just to
128:49 you a practice, right? And here's the, so we need to
128:54 and that's what ends the, the about the sp about what happens to
129:00 water quite interested in the resistivity of formation water. Why is that we
129:11 to evaluate Archie's equation and have to RW RW because we're always looking at
129:19 of movement away from RW based on velocity and the saturation or make our
129:25 more resistant. So it's my starting . So I have to have an
129:30 of a to quantitatively interpret what my is. Thank So how do we
129:38 between uh sodium chloride concentration and just chlorine concentration? Five RW and
129:48 Hopefully, that's pretty standard notation. resistivity connectivity and we get 1000 because
129:56 , this was somebody's sense of Uh This is actually outdated now.
130:00 CW is in mo mh O the of home. They don't call it
130:08 they see in SI E MA N units. I was while I was
130:15 college, it was a while Maybe the oil industry would still do
130:20 . And then the mill, that's , so what happens when I,
130:29 happens to a salinity? Uh connect the RW is my sodium chloride concentration
130:35 up, my resistivity goes down, productivity goes up. So this by
130:45 way, uh this happened for all but um let me move on to
130:52 . It gets clear what you What happens with temperature if I raise
131:00 temperature, whatever happen to my you're right. By the way it
131:04 up. Is this true for all ? I got a, wow,
131:14 , you're pretty good. Most students not know that if you raise the
131:19 of copper, the connectivity goes Ever worried about why ever bother
131:27 Why that would be? No bother . It has to do with understanding
131:39 physics, a meal just for your . Maybe it's just confusing you,
131:47 a metal, the connectivity is determined the conduction band. So you have
131:51 bunch of these large molecules associated with metal, the D orbitals overlap.
131:58 get a conduction band associated with that easy to move electrons from one,
132:04 a molecule to the next, So what happens is if you raise
132:09 temperature, you actually populate those electrons of that conduction dam. So the
132:14 actually goes down temperature, I usually that out to because I talk about
132:21 here, you're understanding a model, apply the wrong model to the wrong
132:27 . You get the wrong, this a situation where that happens. And
132:35 think this is the this is this basically the uh what happens with
132:42 What happened with salinity? Right? temperature, we have temperature on this
132:47 , we have salinity on this So the interesting thing about the chart
132:52 you go between the parts per right? And a resistivity here,
132:58 ? And so if you want to at the affected temperature, I have
133:00 certain resistivity thought we did this, let's say it's 0.3 m and I'm
133:08 50 degrees up. So I'd be here. What happens to my
133:13 Right? If I go to 100 50 yeah. Is my salinity going
133:18 change means by the way are lines constant salinity. What happens if I'm
133:28 and I raise my temperature, I move down this line, but I
133:32 change my salinity, but I am my resistivity right? Till I get
133:37 the correct temperature. So I just these right, get to the correct
133:42 . How I that by the could see how constant parallel these lines
133:49 that has just to do uh with fact that the connectivity in a brine
133:55 related to the number of ions in blind, they are conducted. So
134:01 doesn't really matter. It's quite linear the amount of ions over a very
134:08 range. If I double the I the concentration of the salt, I
134:14 the reactivity very linear over very large . I actually matters later. We
134:25 about uh we talk about wax it daily. So seawater, you could
134:31 ought to remember that's 30 to 35,000 per million fresh waters here.
134:38 salt saturated. That's why things tend break down here. If you look
134:42 this chart, this is uh this pretty linear over quite a long range
134:48 we get out here near it's salt , everything breaks down. So that
134:53 thing I talked about doesn't work once get near its salt saturated. So
134:58 a lot of reasons to understand, , that you where salt saturated
135:03 right? Is a function of right? The higher, higher the
135:09 , the more salt it can make dissolved in the brine. So a
135:14 of times if you have a reservoir is actually near salt saturated, what
135:19 happen when I bring it to the and cool it, I will precipitate
135:28 in the pore system. And when go to measure a permeability. I
135:33 very well get the wrong answer. in with a salt saturated solution that
135:38 dissolve. So you have, if want the absolute perm, you have
135:42 clean the salt out of the So just so you know, uh
135:47 won't do that unless you ask them as you know, enough to ask
135:53 to. So you may well be by an order of magnitude of from
135:59 that's gonna matter to you if you're to make money. Right? All
136:06 . So that was the sp getting to the end. It's a good
136:22 . So we're on to the gamma and why I couldn't get that,
136:31 we're gonna do the exercise memory in ways more important that time, you
136:42 , the day maybe happen. But . All right. So the gamma
136:53 , this is the other tool that we used to determined reservoir from
136:58 reservoir. It's scaled and arbitrary API . So we, they used to
137:05 it here on our campus, but think they moved that test at sugar
137:10 . Now. Um depth of investigation a foot, pretty standard 3 ft
137:17 resolution that we're gonna find in a of the convention density logs gotten a
137:22 bit better. OK. That's significantly . All right. But what are
137:29 doing with the density log much? I had that fine. 13.
137:46 here's an example right? Then there's stereotype that high gamma ray, right
137:52 non reservoir if I have a So we're gonna work our way down
137:57 ask some questions, right? If reservoir is sand and my non reservoir
138:03 shale, my gamma ray of my is gonna be what? Relative to
138:13 ? Yeah, I that's our right? A reservoir is gonna be
138:18 . Shale is gonna be. How if I have a chorus line stone
138:23 a tight line? Yeah, you it. I heard the writings of
138:35 Yeah, it, it won't tell , you read from you not.
138:41 about if we have a granite wash is it fair to ask geologists in
138:45 question versus just a Limone, a ray in my granite? Main thing
138:54 should know better than I probably have belts bar in it. Far as
139:02 . Yeah. So my reservoir is gonna have a higher gamma ray that
139:07 not. And then we have I don't know what the slash be
139:16 to change this. So we have porous dolemite versus a tight do might
139:23 a radioactive response Cassi bear or So again, they would be the
139:33 . So you, what, what gamma ray means? Depends on what
139:37 reward. It's telling you rear versus reservoir rock. No information about
139:46 It correlates you've ever watched a television ? Quickly learn that correlation is not
139:55 or the internet period. Yeah. . Well, we'll see it.
140:04 responds to the tools, responding to uranium. All right. So it's
140:13 for an eight inch barrel. If whole washes out what's gonna happen to
140:18 signal. Yeah, you're gonna lose . Right. It's gonna look
140:23 It's gonna measure the radioactivity of the . Typically. Typically if you don't
140:31 casing, it's gonna be fairly You know, why might you have
140:36 in the mud? Talk about this swelling clave? That's a good one
140:50 you geologists to remember, you can a hero or at least I told
140:54 songs. All right, how about shale for gamma ray which that businesses
141:02 guilty of all the time really doesn't . So we'll, we'll talk about
141:08 particularly when we get to, particularly we get to Shelley and measure for
141:14 gamma ray spectra again, passing uranium thorium. You are looking basically uh
141:21 , and the spectral gamma ray, ? You can actually tell how much
141:25 I have how much uranium, how thorium, why would I want to
141:28 that? Typically potassium and thorium are to shales. The uranium is related
141:40 organ, there are exceptions to So you can tell right source rocks
141:48 shales with organics in them, some that are not, it's a good
141:54 indicator in be uranium. So they there for a lot of you the
142:02 source rock radio steam right by steam because typically you put a lot of
142:10 in raids the radioactivity for that volcanic that they have lots of sources
142:17 drink or radio activity there. So spectral gamma ray tells you how much
142:25 uranium gassier you have already talked about you wanna know that gives you a
142:30 shale. The problem with the B is typically, geologists ought to be
142:36 sensitive to this. If you have plays orogenic clays are your properties of
142:45 orogenic clay or clay formed in place to be similar to your founding
142:51 No, if they are detrital, , then there's a possibility it would
142:58 , they, again, the geologist help here. What's the origin of
143:03 clays? Right? And if I gonna do that, would I use
143:08 lower bounding shale or the upper bound if I thought, and then it
143:17 deposited when my sands were deposited? , you would want to use the
143:22 bound shale, right? It's the of the sequence, right. So
143:25 would suspect in that sequence, your shale would be better, your upper
143:32 would be better than most petro They were clueless when it comes to
143:38 . Which one should they use? couldn't tell you, is it autogenic
143:43 or is it I have no So they could get in real trouble
143:50 you can't really help you. How I do this? And so you
143:57 a, typically they will separate for reason, the sodium and Cassi associated
144:02 kind of shales, not that they a lot of times the spectral gamma
144:07 , they will combine those two as play indicator. So that, that's
144:14 they've done here, right? So have multiple, you, you can
144:18 what's going on here. This is eagle bird. Here's a clue.
144:22 you can see this better than I , but you can see what's going
144:26 right? With the gamma ray right and here, I think I have
144:32 uh my hassium plus my. So am here and I have my uranium
144:38 this column. What's what's going on in the Eagle Ford with death?
144:45 would I want to completely uranium is bigger, passing Dorian is going down
144:57 what I just said, this is play indicator. This is a
145:03 So here's where your good stuff is down here at the base. Oh
145:14 likes to ask me this exact exact question here is my potassium thorium
145:22 , my shale indicator. And so down here, right? You have
145:27 Cassi thi I have a lot of the top. Yeah. So another
145:36 , right? So why am I this? What, what's going on
145:42 ? Right. I have, I potassium, I have thorium, I
145:48 uranium here. So I have a uranium contact in this range right here
146:02 those are not jail breaks because they're indicating shale at all. Pass him
146:08 my thorium everybody. All right, that. And here's a chart that
146:19 remember when this charge came out dating , but I remember when the spectrum
146:25 ray is, when I first heard the spectrum gamma ray. Uh How
146:29 is this chart you have that Not very good. You you that
146:36 will change and depending on what fluids exposed, what the depositional setting
146:41 et cetera. This can be So you can do things like this
146:46 a spectrum gamma ray, but you to locally correlate that response to a
146:53 or something like that. Then it's valuable just off the shelf with this
147:00 kind of interpretation, it's not gonna for you. And so there is
147:05 in the tool, it does give an indicator of plays versus uh
147:10 things like that or radioactive Dolomites or . But you where this shows up
147:16 for is the story of good luck to be locally developed. Oh And
147:34 I talked about the statistics back you average over it is fairly, I
147:46 , you're, you're measuring actually the that existed if you'd done this 4
147:51 years ago, probably would have had much better gamma ray response,
147:56 Why is our core still moving, moving in mars the it's still here
148:07 we're massive enough radioactivity is still generating enough heat to keep the convection
148:13 going. Thank goodness. Right. billion years later, mars, the
148:18 of froze at that that you're measuring 4 billion years. Digital said radioactivity
148:27 still, this is just you and are exposed to this constantly fairly
148:35 there's a lot of stats if you average over it. Uh Again,
148:40 is related fluctuation. Uh you can a little more by slowing the tool
148:47 and I wouldn't worry about flag those cameras are basically gone.
148:54 Yeah. So this is just an of, of the log. Sure
148:59 all seen go. So I think done and we can do that blog
149:08 and squaring. So let let pass out just in time for we only
149:16 one break. So we're allowed to . It's a large zoning and
149:25 and water. Yeah. Um So we go through this, I don't
150:14 I need to lead you step by . The question I can ask you
150:19 your your job here right is to the sand interval in three layers,
150:27 ? Based on re dividing porosity, use the gamma ray by the
150:32 Yeah. It's not our model for of the layers tabulate the the layer
150:39 , bottom depth thickness resistivity porosity, the water saturation using those Archie
150:47 Yeah. And then uh determine the thickness average porosity and average water
150:55 Mm Then we give you the rules the next page or zoning. Basically
151:06 I told you before, then make table for all of this. Put
151:10 together. So first thing, what's first thing you do? I'll go
151:15 it a little bit. What's the thing you should do? Shall
151:22 put a shale baseline in your gamma or ruler will help, right?
151:32 have that help, draw straight their questions. By the way,
151:38 people at home we can go through easiest thing for them to do is
151:42 share their screen, just upload the to. OK. Sure. I
151:57 check them just like everybody else. if they want to ask questions about
152:03 previous in class saturation height model, can do that now too if they
152:08 I just stop. Yeah, Oh sure. Right. The first
152:21 is the shale baseline. What do do there? You put a ruler
152:25 it and you invoke your artistic Where do I think? So my
152:32 baseline and you're putting it in the place. Shale baseline is gonna be
152:38 here, this is a shale. you, you want it right?
152:45 gamma ray is the shale. So gonna be here here. My sand
152:50 gonna be in there. Can I a question about the last one?
152:58 GSP ones, the gamma ray, can draw a shale baseline on
153:04 So shale baseline first, it really my limit. It looks pretty good
153:20 here. And then there's gonna this one's a little tougher,
153:25 Oh You very well could decide which the gamma ray, which one's the
153:36 the noisier one is gonna be the , right? So your shale
153:41 right? It's gonna be, this my high gamma ray. My gamma
153:44 goes, that's smaller there. But shale baseline, it's gonna look something
153:49 that. Yeah. Or yeah, less noise statistically it averages more.
154:03 , I tried to say that because gamma ray is very low radioactivity on
154:09 , right? You're getting so many , right? There's just a lot
154:13 statistics in it because the noise level so it's so high, it just
154:19 there's a lot more statistics in. , it's a lot more statistics in
154:27 . So my shale baseline just here at the high gamma ray it's gonna
154:32 along there. SPD gets bigger in direction. Gamy gets bigger in that
154:45 . They did that on purpose. they look similar shale baseline first.
155:27 I draw, you decide, basically at this thing and decide how many
155:32 you wanna put in this. This where we get a basic insight into
155:37 personality. Are you a lumper or splitter? You're a lumper.
155:44 I tend to be a lumper It's easy to be a splitter if
155:50 using log or something and doing it hand. I actually did this stuff
155:55 hand. My first show. Yeah. It's gonna be somewhere.
156:03 mean, there's some so it's, gonna be something like that. So
156:10 noise in the gamma ray. So want to go through the middle of
156:13 noise? Is this, first of , I will preface this, this
156:19 an art, not a science and call this an interpretation. You go
156:26 the hall and the next guy does , he's gonna get it, person
156:29 it. He's gonna get a different . So uh that's good news because
156:34 you're good at it, you can differentiate yourself. Yeah, Mr A
156:43 noisier for standard one second. The one is the gaming. Oh This
156:59 the game running. This is the . So you should be, you
157:13 be doing this based on, you're do a resistivity analysis. So you
157:18 to zone it based on both the and the porosity looks to me like
157:45 drifted a little bit during this, isn't all that unusual. I would
157:49 something pretty sure this is a This is a shale just from the
157:54 . Draw something like that sp can quite a bit. It tends to
158:03 fair amount of electrical noise. Somebody welding on the platform, all kinds
158:08 horrible things can happen to your sp . Yeah. Um Right. It's
158:43 I'm getting an echo. Yes. me turn something on. I don't
158:57 . I can turn the microphone You can't hear me so she could
159:05 her microphone off. You have on speaker here so you can hear
159:13 what whatever muddled through. Yeah. . The shale baseline. All this
159:32 used for it. Where do I to interpret this thing? So
159:35 I have a shale baseline here. are, are you gonna call this
159:44 san? No, I might, getting, I'm getting a resistivity response
159:53 , getting a ferocity response here. I, I would probably draw my
160:00 baseline, something like this. So here this isn't a very good
160:05 for sure. You can tell because the resistivity because of the ferocity,
160:11 ? Yeah. My porosity is et cetera. My resistivity,
160:16 My my resistivity it's higher. And what, what am I gonna do
160:24 my sp I'm gonna have troubles with sp it, it looks to me
160:29 it drifted. So I would draw sp base line, something like
160:35 So it looks to me like I a sand here or a sand.
160:53 have to decide how many sands do have? So we got a
161:05 right? We can draw the shale like this. You can draw it
161:11 that. If I draw it like , then to me it's like I
161:17 some sand here. I have some here. Is that validated based
161:22 on my resistivity looks like I have resistivity right here. My porosity also
161:31 like so it, it might be to evaluate that. Right. Just
161:36 see what happened. Feeling. So there may be produce of oil
161:42 . You don't know, be worth would be worth a look. I
161:46 say what I, what I was them was if I'm evaluating this,
162:04 gonna draw my shale baseline and I it something that, which case,
162:09 might have a response here for sure . Right? Also, the SP
162:15 look to me like it drifted, I certainly have some sp response
162:19 but I got some invasion here. actually got some sp response there
162:25 II, I would, I would draw my shale baseline, something like
162:30 . And I think you have two to evaluate, then you have to
162:34 how many zones in this do I LG? Maybe 1234. And they
162:50 . I was just explaining to I probably would say yes, there's
162:56 upper sand, right? Which I don't get as good at development
163:00 probably is not as good as right? But it would be worth
163:05 just a chapter. Yeah. Sign peak reading. That's well, so
163:38 , if you're using the gamma ray in your evaluation, which, so
163:43 was just the point I was making . If you look at this and
163:48 interpreting these wiggles as statistics, then wanna put your, you wanna put
163:55 Sony pick through the average of not at the peak values. They
164:01 , OK, then that's because you're that as statistics. So it's just
164:06 , right? So it's gonna fluctuate the true value whereas on, on
164:12 other logs, right? You don't that statistic. So you really are
164:16 pick it at peak values. And if, if uh again, like
164:22 say, this is an art, ? So I would put my shell
164:27 something like that. Yeah. And I have to decide once I do
164:35 , I'm gonna not gonna use the Rape or anything other than pick where
164:38 sands are, right? So where's sand? This is obviously a
164:44 And I would say this is probably sand, but I would pick maybe
164:52 , depending how picky you are. could do 34, maybe five zones
164:58 maybe just call this a zone or zone. There's really no right or
165:05 there. The gamma treat a little than the other one just because it
165:12 so much statistics to it. Is OK to like for, I don't
165:54 . No, no, I think would be fine. 123, I
165:58 either do 45 or just just want together either way, try it both
166:05 . See if you get a significant . What seven, if you're
166:13 then do four, then your job to find the oil, right?
166:24 , the well paid all the If that upper zone produces any
166:29 it's like you're a profit, You already spent all the money.
166:33 the cost of perforating, just whether think it's gonna produce much water or
166:39 , but it's higher up in the , right? So, if you
166:43 think it's all in the same then, uh, it's probably just
166:49 make oil. If you can get in it. They're all the questions
166:58 asking yourself. I can, can I ask something? Can I
168:00 my screen? I don't know if can hear me. Yeah. So
168:08 your shale baseline on here side, side, this is the sand,
168:13 is the sand, right? So got this zone and we got this
168:18 . So I basically have this, and I have this zone, maybe
168:24 zone. So let's call it four . So I just need to zone
168:29 square those four zones. OK? , yeah, you have your geologic
169:35 all done know. So where, your sand? So we have two
169:53 that we're gonna do after that. don't care. OK. I'm not
169:58 use this for anything just evaluating arching . So I zone off here and
170:04 zone where it changes my calculation, ? So you have to decide what
170:08 errors are. So if I were it in this class, I've got
170:14 here, zone here. It shall here and again, it gets smeared
170:18 , right? Because it's, then got another sand here. It's probably
170:22 enough based on what's happening with my . Right. Not seeing much difference
170:29 . Yeah. And then I maybe two zones here. One here,
170:33 here. So I, I I do my best to draw a
170:39 zone across these lots. So those are within the state. Yeah.
170:47 don't care about the jail. What I gonna do with those?
170:57 You may have a specific reason you to do that. But we're
171:02 trying to make money that calculates that . I just takes a little bit
171:18 get an eye for doing this. you haven't done it, if you
171:22 more experience with a particular reservoir, get better at it. I'm
171:31 you need to. Well, I two major sand bodies red. I'm
171:38 evaluate right? And I would say and here, right. So gee
171:43 , I looks to me because we at here, I got a zone
171:47 correspond to that that corresponds to I know they're a little bit
171:53 Yeah, on here. Yeah, . OK. And we could do
171:58 one too. And so then, then what goes on here maybe one
172:03 and one year and they have pretty to the same ferocity discussion about.
172:43 what you both said this is Yeah. Yeah, I just see
172:51 sand zone. Well, see she a shale baseline. She, she
172:58 her shale baseline a little differently than would have. I would have drawn
173:02 a little bit to the left just on the sp I'm seeing some indication
173:07 the sand there. So I would drawn this a little bit more vertical
173:11 she did. So I get based the sp I really have two intervals
173:17 , right up up here. And then here where my sands
173:23 And just because I'm seeing it also my resistivity log, I also see
173:27 reasonable response here on my porosity So based on, again, based
173:35 all of the logs, I don't I would have called just this,
173:39 sand. I, I would evaluate one because you're looking for, you're
173:45 the well, or you're looking for possibilities for oil. There might be
173:49 of oil. What about jeans are real lumber? Yeah. So,
174:01 here I, I really wouldn't have all that and that's why you're seeing
174:07 on the sp I'm not seeing it the camera. Yeah. Say
174:15 share my screen so they can see they would tell me, can see
174:21 point. Yeah, because this is figure and they cannot make a point
174:27 the mouse. Yeah. Yeah. . Mhm. Mhm. Mhm.
175:04 went, I can see what change person a little more obvious.
175:21 So, somewhere and if not, all right. If they can see
175:31 , they can see it. So different slide here, I think this
175:38 baseline is probably all right, it's vertical. And I really think based
175:43 my sp response, adding that I don't have a real big gamma
175:49 response, but this is probably a beed shay sand. And also I'm
175:54 some hair during my log here and also see some character in my ferocity
176:02 here, right? So I, really would have had two sands
176:07 I, I would have, I have sewed this into one sand.
176:11 , I would have actually this bed . I would have moved down a
176:15 bit based on not sure where that boundary came, but I, I
176:19 have moved my, the inflection points like here. Now, it's not
176:24 right here and here is based on ferocity. I also would have moved
176:29 bed boundary a little bit this one I'm really not seeing much character in
176:35 resistivity or in my gamma ray. , I probably wouldn't have called that
176:40 sand. I would have just called a shale. I've seen a lot
176:44 character in. So I, and I'm not seeing anything in
176:53 but one could almost argue that it goes the, yeah, that's
177:03 we haven't really talked about it And so I would, I would
177:07 called this a sand. I would called this zone a sand,
177:11 And then I would have left it . I would have evaluated up here
177:16 . I, I think that this did but I would have drawn another
177:20 boundary here and if that sounds not I would have worried about this
177:28 uh, it really looks like a both here and, uh, I
177:34 I, I know you're seeing some here. I, I would have
177:52 ? Mhm. Yeah. So well, the y yellow line
178:04 yeah, yellow line is like shale . The yellow line is the shale
178:09 . Everything to the left, right , is my, is my
178:15 The high gamma ray here, low rays to the left so that this
178:20 be a sand and this would be Yeah, so the shale bit,
178:26 is all shale at the bottom and you're starting to see a little bit
178:30 a little bit of character here. much on here at all. So
178:35 if this was a sand down it would be pretty poor. It's
178:39 a pretty high gamma ray and you're seeing any real invasion here, in
178:45 , you're seeing a little bit of here and here, but my gamma
178:50 is not supporting it. So just on real preliminary stuff, right?
178:56 II I would suggest that my bed , I I would move this bed
179:04 down a little bit and I would this pet boundary perhaps up a little
179:10 and then I would put another boundary that this really looks like a shale
179:16 on this. Um It burns down . I don't know what that means
179:49 . OK. Like that. Yeah. Time if I put my
180:22 baseline, I, I would not that a shale, I, I
180:25 make this more vertical. So just on my response to my other
180:32 right? And my sp I'm developing sp here. So I, I
180:37 you're shale, you have a I think your shale baseline on auto
180:42 vertical, give you some room, like that. My sp that would
180:48 up for sure. Right. I've sand there. So honoring that.
180:53 also because I'm seeing a response and seeing invasion here. So I,
180:57 really think that might be worth evaluating also my ferocity, I'm seeing a
181:02 , right? So I, I suggest based on this even though you
181:10 seeing a little invasion here, I your gaming, if it is a
181:14 , it's pretty, pretty crummy because got a pretty high gaming,
181:20 But I, I think I would that in my sands. I'm seeing
181:24 lot more invasion. I'm gonna call a sand. I'm seeing more invasion
181:28 than there just like here. I'm a little bit, but it's really
181:32 like a shale based on this and sp. So based on all of
181:38 , I would call this my sand this my sand Right. And I
181:44 my bed boundaries here here. you could call that a lobe of
181:50 if you want and include that. , just this little shoulder. So
181:55 123 zones here and two zones Oh God. So that, that
182:03 , I have a problem because I'm really seeing any invasion and that could
182:09 like, uh, a mud tape something like that. But because I'm
182:14 seeing anything on M MA or sp seeing anything on my and engage in
182:21 . I know you haven't had but just the separation indicates some level
182:27 is gonna be. So I'm seeing separation and this one would be pretty
182:34 . So if I were doing it if you're a splitter, you could
182:38 all of that if you want, you're a bit more of a
182:41 right? Yeah. Yeah, which tend to be, I'd have more
182:46 12345 zone in my sand is my sand. The possibility of some sand
182:57 here again, based on kind of separation here, I'm seeing some ferocity
183:03 . So I'm looking at all the trying to make sense out of all
183:06 them. Kind of interesting. There's evidence here that SP is developing.
183:14 have an invasion here. I'm seeing here. I'm getting mud filtrate into
183:18 . It is fairly high game, ? So it's probably pretty chroming
183:24 but I am getting some invasion and getting an sp log, seeing some
183:30 on my resistivity, right? And seeing some character in my porosity
183:36 So between all of those things, shale is pretty high porosity. This
183:41 more than some variation in the shale . I'm seeing no indication of sand
183:46 these or these, right? But am seeing some here, but this
183:51 be a wash out. This could I'm having trouble with my shales.
183:56 , seeing some washouts which is gonna me AAA Coity. We haven't really
184:04 about that yet but just telling you I made the decision. So here
184:10 , I really would, I would evaluate that. I would evaluate that
184:15 those sands. I would separate this two lobes getting significantly different resistivity and
184:22 showing some, you know, a of character but some character in the
184:28 and then a hero, here's, my main target. Sure.
184:34 this one's kind of iffy. You do it just because why not?
184:38 then, and then there's just enough on that. I'm willing to disco
184:49 51 time. Yeah, absolutely. , absolutely. Um And A C
185:15 one. Always one. What what, what's A, I don't
185:20 what you're using for A, you , you have mm equals N A
185:26 the same as C and it's one usually use fractionality. OK.
185:49 No, no, no. Don't the shales. That's the main
185:54 We're using the SP and the gamma force to throw all of that rock
186:00 . I wouldn't even know, can't Archie's equation. Wouldn't even know how
186:04 evaluate it. Can't use Archie's equation shale doesn't work. Yeah, I
186:22 . Yes. Ok. That's good for now. We, we don't
186:26 how it is correct or invasion. I think it said that in the
186:34 . Ok. Uh, you should the homeworks generously, grades almost all
187:23 the final. Ok. Ok. . Really? I Mhm.
188:58 Yeah. You, yeah. Thank you. Um Yeah.
190:35 Uh, but this, this will done. Yeah, I might,
192:07 was gonna call that part of my which you might, you might have
192:13 zones or even 12 and three zones that doing that, that, that
192:19 be worth evaluating, particularly if you a response here in Vero.
192:55 Ok. Yeah. Um, so get a feel for this since you
193:10 it, then what's gonna affect your , right? Yeah. Yeah.
193:19 , and then again, as I across where things change and clearly,
193:24 think my porosity changes a little bit here and here. I think you
193:30 pretty safely call this two zones. porosity change a little bit, my
193:35 responded a little bit similar here. lot of people are evaluating that.
193:42 I'm seeing a, seeing a corresponding change. So maybe 12 and I
193:49 probably call that one zone, really seeing much of a response there.
193:54 the rest of this, I would call just a shale indicator. Even
194:00 I'm seeing some invasion I got pretty gamma. Right. I'm thinking that's
194:05 not very good stuff at best. this is my real possibly this.
194:13 , just based on what I think relevant changes, I have maybe
194:22 So, maybe one. Yeah, sure. 12345 cents I think would
194:28 a reasonable for certainly for the purposes this class. Oh, well,
194:41 you're feeling kind of a shoulder here seeing a similar response here.
194:48 actually originally I wouldn't have done but some people are doing that.
194:53 again, it's an art. So up to you. It's, you
194:57 , my resistivity has gone up a amount and I am seeing some response
195:05 similar deaths here. So maybe there's there or maybe not. Either way
195:15 wouldn't be wrong if you left it or, or it'd be a judgment
195:31 done. Yeah. How much oil you buying? Where was the
195:48 What? Oh, you are a . So this whole thing had
195:57 This one did not? Oh, , you have 1 57 up
196:05 67 water or 67 oil water, have a water saturation in it.
196:17 that's a calculator. Water sa. right. So now, yeah,
196:25 oil here might be. All And then what percent, how much
196:30 here? Really? 100% oil No, that's fine. I would
196:41 be tweaking my Archie parameters if I 100% that's perfectly plausible. You're,
196:51 gonna calculate that. You get something that. Normally you would say maybe
196:55 need to rethink my ar parameters or my RW or something like
197:02 Right. So I would be looking refine it, but definitely oil
197:08 maybe produce oil there. That's probably . My porosity is significantly better
197:21 I would expect this to be So a lower oil saturation might make
197:26 . Right. So, I think could make a good story out of
197:31 for your boss. Still might be oil. You still might only produce
197:36 . There might be worth uh perforating . Sure. I'm leaving it back
197:53 somebody persuades me to stay. So tomorrow still start at nine.
198:06 . Yeah. It's long enough in my opinion. Plus time makes
198:12 stay longer than that. I ain't it and he never has everybody.
198:21 , that's a long thing. 8 5 long enough as it is.
198:30 get tired and they stop working in experience. Just, you don't get
198:35 out of them already. It's a day. Right. How many weekends
198:54 ? This course? This is our weekend, right? So, it's
199:03 or three, four weeks. But last week we only have courses on
199:11 . Then we have a mid, have the final at some point,
199:16 a week later we have next So we have next Saturday following
199:26 Saturday and then next Friday we have . Thanks. Yeah. All
199:43 Ok. I'm gonna use them to my computer here again. What about
199:59 ? I'll just leave it on That spelled 20, sure.
200:09 yeah. Yeah. Mhm. Can hear me? Yes. Yeah,
200:21 can hear you. OK. I had a question. OK.
200:32 got confused around these. I wasn't what the saturation profile looked like if
200:40 something like this or like this or this like a straight line.
201:02 Now you can hear me. Can she see my cursor now?
201:08 you want to stay, you wanna on the lower blue curve is till
201:13 come up. Looks like you have mostly right? I don't know what
201:16 drawn blue curve is but you just your saturation is calculated by tracing out
201:22 appropriate cap curve at the depths you're . So you're on that blue curve
201:27 , you come up to where you to the red curve and then you
201:31 that one and those are your calculated like this. Yeah, except you're
201:37 on the curve. Yeah. Sure. OK. And then for
201:42 producing water. So that's where you , so it's just it's a little
201:48 past the point of maximum curvature on cap curve. So the way you
201:53 that is you draw a tangent like it's on the blue curve, you
201:58 a tangent. So no, it's literally a tangent to the
202:05 Oh Like this. No, just tangent. It, it basically just
202:13 I could draw it for you. Yeah, you got close, you
202:17 past it. So yeah, you to follow the curve, you draw
202:21 tangent, it's in the notes how do it. Yeah. And then
202:26 draw another tangent, you draw a , you draw a tangent and then
202:31 go straight up from where they cross the curve. OK. Yeah.
202:39 here. Uh Somehow, somehow I draw on the curve. I could
202:48 you quite easily. There's some, some way for me to draw on
202:54 . Uh I can quickly, Even even with the mouse, quickly
203:00 shot for you. Hang on, a second. We're gonna work this
203:08 . Screen shot. Yeah. you can stop share right now.
203:19 then we will share and I'll draw it. Yeah, that's a good
203:25 . Share a screen. And where the up here? So,
203:37 that's fine. So I could draw , hold the button down to
203:43 Can I see the cursor? Hang here. It is. So you
203:48 a tangent, it's gonna look something this and then another tangent here that's
203:55 look some of it. Oh I , it's gonna look something like
204:00 And then from where they cross you straight up, I'm attempting to go
204:05 up and that's your critical water saturation there where I'm attempting to put an
204:15 . OK? I think I remember . Yeah. Yeah. Yeah.
204:17 just past the point of maxim OK? And if you don't have
204:23 on the, on the red I mean, you could be close
204:27 it. You, you could have than one critical water saturation, you
204:31 could produce you. Actually, I'm gonna assume, you know how to
204:37 it. Now, I can find cursor, evidently I could go off
204:44 screen or something. I find it there. All right. And in
204:53 , you, you might have another water saturation right here. So it's
205:00 point them at point past that point minute, you could have more than
205:04 place where you would start to produce . So the point is what would
205:10 be happening here? It's all along top curve. You would be producing
205:15 oil. First of all right. see, you're, you're not,
205:22 on the blue curve where that second drew is. So you would only
205:26 oil out of the red curve out the chlorite sand, but you would
205:32 only oil up up here and the sand and the clean sand and then
205:38 would start to produce water starting here to what I drew. Yeah.
205:46 even though it's, even though it's poor sand, you would produce only
205:51 out of it because you're higher up the curve. I understand. Thank
205:56 . I, I have a question . Can you hear me?
206:00 Uh What's the transition between the two ? How sharp that needs to be
206:06 the, the blue and the red it doesn't matter or? No,
206:11 , it matters. That was. the, what you did was
206:15 we scaled the thing right above the level. We had a depth tie
206:20 where we put absolute depths on We've done that to the right of
206:23 curve. And then once we have on it, we can put our
206:27 on it. And then the geologist where the upper sand ended, where
206:32 , where the LRI sand ended and it was halfway in between. So
206:37 knew that depth in there just from geologist where we transitioned from one curve
206:42 the other. So you're on, use the appropriate cap curve for the
206:47 you were in. No, but I mean, uh,
206:51 I there's a limit between the two , right? But how, how
206:57 is that trans transition from the, sun, the sun below and the
207:02 sun? It's like a sharp Yeah. Well, I mean,
207:07 sharp is the bed boundary? You'd have to look at the and
207:12 that typically with the accuracy that we things. He would draw a line
207:16 he would just switch curves. There be a gradual transition or it could
207:21 pretty sharp. Right. Just depends what, what happened with the geology
207:27 . Hm. Ok, thanks. . Bed boundaries tend to be fairly
207:35 . Yeah. All right, But there's so part four here.
207:51 . Is it wanting, is it us to do that for each zone
207:57 all the zones together? No, . So you want to take each
208:00 your zone, determine what depths you your bed bings at what your thickness
208:05 , what the porosity was, et because we, we did that in
208:09 two of this question, top depth of layer thickness, deep resistivity density
208:16 value or the terms of the total man. So, but they want
208:21 to average is all that's OK. you have a total thickness and you
208:24 to do a depth related ferocity Remember the H times speed and then
208:32 H times times BW. So they want you to calculate oil right?
208:41 each individual. Yeah. And you're average them. So you, you
208:46 did eat zone now. Yeah, , you, you did eat stone
208:50 , right? You resistivity test, cetera and you're gonna calculate a saturation
208:56 each of those zones, right? then they want you to average
209:00 right? OK. OK. Sorry that oh is in the weighted
209:30 . Yeah. I mean, to leave the computer here, is that
209:37 right? As long as the uh, that gets lost that,
209:55 , yeah. Right. Any final questions?
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