| 00:20 | You know, gets a little tougher my favorite, the acoustic block, |
|
| 00:26 | ought to be interested in uh has uh including the kitchen sink and the |
|
| 00:34 | and doors in the kitchen uh that vaccinated. So a lot of really |
|
| 00:39 | physics, um glass half part of and everything is involved, the glass |
|
| 00:45 | everything involved. So um I'm not this is really true, but uh |
|
| 00:54 | matrix is known and, you you don't have a gas, then |
|
| 00:57 | lot of times you will run similar , which just because it's the easiest |
|
| 01:02 | interpret. So it probably gives you best number of uh independent. Then |
|
| 01:10 | have seen uh carbonate people. Um build models that basically had more than |
|
| 01:18 | logs in interpreting theology. So trying get some of the lesser on the |
|
| 01:25 | but and it was over i another . Yeah. So um and there |
|
| 01:35 | , you can take classes now, general classes where you take a whole |
|
| 01:39 | of blogs and interpret about people doing analytics to cover that, things like |
|
| 01:47 | where you any number of blogs, ? You get it be a little |
|
| 01:57 | because they get over. So, velocity can be determined. Uh This |
|
| 02:03 | think is emphasized right now. It's of multi mineral models. There |
|
| 02:09 | for example, has modules that enable to do that. Uh People in |
|
| 02:15 | class experts in data analytics. Did ever use data analytics? Do you |
|
| 02:21 | any interest in using data analytics? , you might want to, it's |
|
| 02:26 | be uh it's it's gonna be tools you really need to bring to bear |
|
| 02:30 | long as you use them correctly. any uh data analytics integrate just gets |
|
| 02:37 | . I bring that up at other , don't make sense to do uh |
|
| 02:42 | blogging. Uh Again, widely time historically including myself spw a paper with |
|
| 02:52 | , use it when appropriately and when appropriately. It's OK. The physics |
|
| 02:57 | all wrong. It's actually ridiculous physics using it is interpretation to it's a |
|
| 03:05 | fit to the acoustic blog and uh the dependence of it. It's not |
|
| 03:11 | density neutron is uh fantastic indicative of . What we talk about. Hopefully |
|
| 03:19 | understand in detail why basically they have responses and gas. So a separation |
|
| 03:29 | it really is a good gas And then yeah, you could see |
|
| 03:35 | show some examples of that, when can see the change and shale clays |
|
| 03:43 | every log, by the way, same down, right. So the |
|
| 03:49 | we could talk about the detail of clays affect all of the porosity logs |
|
| 03:54 | more or less particularly acoustic log in very complex way. And also the |
|
| 04:01 | new dr they like that you need think about light and their impact on |
|
| 04:11 | aspects of the, the it's got huge impact. So uh might cross |
|
| 04:21 | the reason that you do that um tools, all of them are compensated |
|
| 04:27 | been compensated for a while. If talk about what a compensated tool, |
|
| 04:35 | a good time to do it to it up. The tools all started |
|
| 04:38 | as would say, basically a single . And then what they do is |
|
| 04:44 | add, they've added a second detector all of them density to the |
|
| 04:54 | And what compensated me is that you those two detectors, you're gonna use |
|
| 04:59 | ratio of them uh typically uh some of two to actually remove uh the |
|
| 05:08 | loss. And whenever you have a , you also you have a slope |
|
| 05:12 | that correlation and then you have to the correlation of the plot that's gonna |
|
| 05:17 | the inner something. So what will to drift far more than any measurement |
|
| 05:23 | all the lab measurements, right, offset will be around pressure trans. |
|
| 05:31 | if I can minimize the impact of , right, it should be by |
|
| 05:35 | the difference. For example, the they all go away which are slow |
|
| 05:41 | remain much less. So we'll see their tools, they basically use a |
|
| 05:49 | of the difference. The reason for is that part of the calibration is |
|
| 05:57 | fact that its temperature with all kinds compensating tools are much uh newer |
|
| 06:06 | Uh li density. This is where would change its drive long space acoustic |
|
| 06:17 | actually so not new. People used for a while and they very rarely |
|
| 06:24 | . Most of that was a really know very much full wave |
|
| 06:33 | Uh So die Sonic, et That's kind of probably the most, |
|
| 06:41 | just that you get much better. of the reasons you get much |
|
| 06:45 | she get a full away, you that the case. All kinds of |
|
| 06:50 | things are related to that. That's pretty common. Now, all the |
|
| 06:58 | have gotten lighter, cheaper, more people wanted to go deeper things get |
|
| 07:03 | , et cetera. Then the last we're gonna cover, which I like |
|
| 07:08 | cover last as it together. A of the concepts of the. So |
|
| 07:13 | , we will, it's kind of good review of the things we talked |
|
| 07:17 | . We really haven't thought about. kind of a summary of what. |
|
| 07:25 | let's start with the uh compensated density the lift the density log, there's |
|
| 07:33 | radioactive source which makes it not much to stick, stick a radioactive |
|
| 07:39 | And what does that mean to your ? Not much good. It's a |
|
| 07:46 | source. You're not allowed to go and grind the tool up. |
|
| 07:49 | Kind of a bad idea. People are afraid of getting the radioactive |
|
| 07:55 | to your groundwater. If you don't it, I don't want it. |
|
| 07:59 | . So, you have to fish this thing. Uh, usually at |
|
| 08:03 | a few days before you can give . And then if you don't, |
|
| 08:08 | , fish it, you actually have plug and abandon that section of |
|
| 08:12 | well, you have to plug past tool, right? And then you |
|
| 08:16 | to go in, you still have money to complete the, well, |
|
| 08:19 | gonna sidetrack so it costs you lots money. So um we'll see with |
|
| 08:26 | new trio, they actually found a around and Frank, you still have |
|
| 08:30 | gamma ray detector related to it. simulation counter. If you look |
|
| 08:36 | at the uh what happens with the gamma rays, uh There's a, |
|
| 08:42 | a, there's a pad tool. is because the depth of investigation of |
|
| 08:46 | gamma rays is very. And then here's one of the main points of |
|
| 08:51 | physics and one of the answers I expect you to give on your final |
|
| 08:57 | is that it measures basically electron Remember what the SP tool measured? |
|
| 09:07 | think you remember it, I hope was a resistivity contrast of the mud |
|
| 09:13 | , right? And your and your , right? So there is the |
|
| 09:19 | there here you are measuring electron you measure it via in the compensated |
|
| 09:26 | , a comp scatter. I don't if you had this, possibly even |
|
| 09:32 | your high school physics class I like in your sophomore level physics. If |
|
| 09:38 | basically the electromagnetic radiation gamma ray is example of fairly high frequency. Uh |
|
| 09:46 | can, that can interact with a particle. So you literally can scatter |
|
| 09:51 | boton off an electron. So what happen is your gamma ray will lose |
|
| 09:58 | and your electron gets kicked off something ? And so it will the energy |
|
| 10:04 | the gamma. Then I'll, I think I have a picture of |
|
| 10:10 | but it will continue to scatter off until ultimately, the energy gets low |
|
| 10:16 | that you will have photoelectric absorption. your gamma ray energy becomes comparable to |
|
| 10:22 | K shell electron and and an atom then it gets absorbed and it's |
|
| 10:29 | So uh this brings up another point versus absorption scattering is always, always |
|
| 10:38 | , less li dependent than absorption. the competence scattering is a good thing |
|
| 10:47 | that you won't get a whole lot li patient, not nearly what you |
|
| 10:52 | out of total electric absorption. That's whole point of the tool. It's |
|
| 10:58 | photoelectric absorption rather than its content So the answer for uh compensated |
|
| 11:09 | what is it measuring? Yeah, measuring electron density. Then the assumption |
|
| 11:16 | be that the electron density is proportional the density. That's how we get |
|
| 11:25 | it. That, that's how basically that assumption, it's actually pretty good |
|
| 11:30 | not exactly true. This is part the biology dependance here. It's the |
|
| 11:37 | that that isn't exactly true. then absorption, this is dramatically, |
|
| 11:44 | mean that the primary use of that to live the density tool which is |
|
| 11:51 | that is to get independent of. this is my point, my electron |
|
| 12:00 | is proportional to the. So I ask you basically, this is called |
|
| 12:09 | , this is called a cross This is a volumetric absorption uh or |
|
| 12:15 | a cross section photoelectric cross section related that. And that's just a probability |
|
| 12:22 | the gamma ray gets. It's just in an area, but it's called |
|
| 12:27 | cross section. It's just units of scrat them. That was a physicist |
|
| 12:35 | sense of humor where that unit was big, it was as big as |
|
| 12:40 | barn fine that helps you work. . So the compensated density, as |
|
| 12:50 | mentioned, we do this at high before things get absorbed. So we're |
|
| 12:55 | measuring scattering effects or clot is here through uh that's relatively worth biology |
|
| 13:03 | Again, this thing doesn't seem very , the gamma rays don't get very |
|
| 13:07 | . So mud cake has a very part of this tool. And so |
|
| 13:13 | will primarily one of the primary In fact, it's so important to |
|
| 13:18 | it on the log, right. , will be uh mud cake correction |
|
| 13:24 | wash out with ghost. Nobody knows a ghost means. This big washouts |
|
| 13:30 | real irregularly shaped organs. So, at mid densities, right? Uh |
|
| 13:38 | roughly four inches, even pretty easy have a couple inches of mud |
|
| 13:42 | So you really can have a significant . Uh lower densities and slightly greater |
|
| 13:49 | higher density is slightly less. So brings up, uh is that obvious |
|
| 13:55 | you why that would be so primarily is, that's a leading question? |
|
| 14:01 | somewhat rhetorical, right? So, what, what are you measuring, |
|
| 14:05 | measuring an electron density? What's the typical density of a rock? Let's |
|
| 14:12 | because it's kind of the middle What's the density of water? |
|
| 14:17 | So what we already have probably a of three OK or rock. How |
|
| 14:24 | the fro it's maybe 25% of the volume. So we have a factor |
|
| 14:31 | three times a factor of four, or take three are in order of |
|
| 14:36 | more sensitive to the amount of rock we are the four fluent. So |
|
| 14:42 | tool because it measures electron density is measure the amount of rock in the |
|
| 14:51 | . I find that opposite to the Trump, discuss that story. So |
|
| 14:57 | quite important because it gives you insight all of the effects of the |
|
| 15:03 | right. So at at lower bulk , this makes sense, it would |
|
| 15:10 | further because the density is less, less electrons and the gamma rays will |
|
| 15:14 | deeper at higher densities like Bola rather , they will have slightly less. |
|
| 15:23 | sorry. And the depth of investigation be less than high densities on |
|
| 15:30 | Is that OK, directly related to it measures? And uh the fact |
|
| 15:37 | that's primarily uh contributed by the rock of gives you that result, I |
|
| 15:43 | warn you. Now, it because neutron log give away a lot of |
|
| 15:48 | excite that it's basically measured the four . So one measures the rock, |
|
| 15:52 | neutron and measures four fluids talking about that is second, not one of |
|
| 15:57 | second hour or so, maybe. so, uh and so, uh |
|
| 16:05 | if you have one answer, if remember the answer for the density |
|
| 16:09 | the answer is opposite for the neutron , right? Big insight as to |
|
| 16:16 | going on. Yeah, it's vertical . It's actually better than this |
|
| 16:21 | Uh You can get if you're willing run it fairly slowly with the new |
|
| 16:27 | tools, you can get it better in terms of the resolution. So |
|
| 16:32 | important if you're trying to understand for example, that will help you |
|
| 16:37 | that right. Uh And so if you're willing to do signal, |
|
| 16:41 | things like that, run it you can prove that resolution as in |
|
| 16:47 | there are four whole corrections related to , which in general you don't want |
|
| 16:52 | do a pretty complicated I wanna show a picture of what you know this |
|
| 16:58 | . OK. Right. Measuring full told you what the ghost was. |
|
| 17:04 | can see the tool is actually a tool. So even the standoff |
|
| 17:09 | depending on the amount of blood which stand off or the hole is, |
|
| 17:14 | have a significant effect on the See that here's what the tool looks |
|
| 17:23 | . Compensated or uncompensated. You have short space detector and a long detector |
|
| 17:30 | nobody wants and compensate for it. is a compensated tool, right? |
|
| 17:37 | detectors. So we we're gonna look the basically the measurement is gonna be |
|
| 17:42 | to a ratio. And so for , as your source decays, it's |
|
| 17:47 | be less intense, right? So overall magnitude of your signal will get |
|
| 17:54 | as that source ages, but the of the two will remain relatively |
|
| 18:01 | the whole idea, right. it will rotate around the core |
|
| 18:15 | right? But you are pushing it the no, you're right. All |
|
| 18:21 | tools do that rotate, they go . We talked about an oriented core |
|
| 18:27 | we talk about one of those right? We know the position of |
|
| 18:31 | tool is usually happening some sort of to locate what, how it's if |
|
| 18:39 | have an oriented core, probably better of that than so two detectors compensated |
|
| 18:54 | all uh the source. And then measure the ratio of these two |
|
| 19:01 | So this is uh as I was about, this is basically what is |
|
| 19:06 | a spine and rib plot spine doesn't real straight or the ribs. But |
|
| 19:15 | what this is, these are actually these are measurements in A B, |
|
| 19:22 | measure this as a standoff. But have normal muds here, be ice |
|
| 19:29 | on the opposite side of this right? And this is basically what |
|
| 19:35 | is we are averaging in a mud along with our rock signal. So |
|
| 19:42 | will happen to these, all of ribs is ultimately, they all go |
|
| 19:47 | over and end up back here because mud cake gets thicker. And |
|
| 19:52 | we will simply be measuring a mud , but that we really don't care |
|
| 19:58 | that much, right? So we to correct for that. The other |
|
| 20:04 | that's important is if these risks, we do to correct for it, |
|
| 20:08 | we just take, take the chart the tool software takes this just tracks |
|
| 20:16 | to the spine of the spine and spot to get the true answer, |
|
| 20:21 | get drawn rate. So if you're there, there is no correction to |
|
| 20:26 | made if your ratio comes up that is the short space detector counting rate |
|
| 20:32 | the long space counting rate. So looking at a ratio, the standard |
|
| 20:39 | to give us density where you have the mud or actually on this side |
|
| 20:47 | the chart, why would that it has a very high density, |
|
| 20:55 | . Therefore, it's actually more dense the formation. So we have to |
|
| 21:00 | back towards lower densities, right? make the correction, you have any |
|
| 21:07 | amount of bear, right. Why you add bear right to the |
|
| 21:11 | Because it's so de and you want wake the butt off, right. |
|
| 21:16 | this is about accounting for poor right? We didn't really go through |
|
| 21:22 | mud logging here, what it takes be locked out. But why do |
|
| 21:26 | put mud in a door hole? , one is to balance pressure, |
|
| 21:36 | ? If you don't, if you do this right? At the |
|
| 21:39 | For example, uh you can get blowout, which is not a good |
|
| 21:43 | , right? The other is to mud builds mud ft trade that minimizes |
|
| 21:50 | , right? Water is just that ever a spur loss. You look |
|
| 21:57 | where you're just gonna get some everything all time. Typically a mud trade |
|
| 22:02 | a lower current, but we played against the wall. We will slow |
|
| 22:08 | the rate of the page. You less of advance and show you that |
|
| 22:15 | . We had the last election we like to minimize that page that makes |
|
| 22:20 | easier for us to get to our , for example, right? So |
|
| 22:25 | you do, if it lied this would be an easy one. |
|
| 22:28 | would just track your way down. is actually kind of a bulk density |
|
| 22:33 | something like 2.4. So anywhere we on that side, right? So |
|
| 22:41 | fair, right, we're gonna be the other side, you know, |
|
| 22:45 | we would track our way back if can so significantly different ratio depending on |
|
| 22:51 | mind, right? And our, what would happen? This tool really |
|
| 22:57 | suffer from bad. It, the that's so yeah, I'm gonna show |
|
| 23:14 | in a minute. That's a fantastic in whatever we could say next. |
|
| 23:19 | . So what, what's gonna happen as my correction gets too big, |
|
| 23:23 | curves all coalesce go back. So have no way if I'm somewhere out |
|
| 23:30 | , there is no way I could back because I could take this |
|
| 23:34 | could take this one. I could any of these spines get back. |
|
| 23:38 | literally, I cannot interpret the tool my direction gets that big and that's |
|
| 23:46 | the, those are those blue right? So that's roughly where these |
|
| 23:52 | all coalesce with each other. I know what the tool is telling me |
|
| 23:56 | that point, right? And that's 40.5 g per centimeter the density |
|
| 24:04 | When my delta rope gets that it's actually drawn on the bar. |
|
| 24:07 | gonna show you in a second. believe that you will ask this. |
|
| 24:17 | . So that's, uh, here's delta road correction here and then they |
|
| 24:24 | draw on your right. So here's borehole diameter here. And you can |
|
| 24:32 | what happens when my hole gets way of gauge, right? Is my |
|
| 24:37 | , my uh delta row gets My density just goes nuts, |
|
| 24:42 | So I cannot interpret. So this , and I think even here, |
|
| 24:52 | last thing to draw on this is delta road correction blue lines. The |
|
| 25:00 | gets that big which you can see in, happened in the washouts. |
|
| 25:06 | I, I can't direct it to example for you of how to zone |
|
| 25:12 | have it, spread it for but please get zoned everything what's going |
|
| 25:19 | this? They are saying here was them porosity. Uh This is my |
|
| 25:25 | bulk density plotted here. So as bulk density goes down, my porosity |
|
| 25:31 | going to get bigger. And they plotted the bulk density here because |
|
| 25:36 | is willing to commit to a So it's a fairly simple res of |
|
| 25:42 | to go between bulk density. If know my grain density, when we |
|
| 25:48 | about cutting the cord, one of reasons the geologist Petros, the |
|
| 25:54 | sometimes it wants the cod is to the brain density that it wants to |
|
| 26:00 | a variable brain density model for the of the we gonna see how that |
|
| 26:07 | in just a second. I think what I wanted to say. These |
|
| 26:23 | , right? Which are basically what this is right? Is it |
|
| 26:28 | reflection of where uh your logging to whatever. So you, you can |
|
| 26:35 | basically how fast you can do. we already answered this question in these |
|
| 26:47 | where we have washouts, we get mud cake effects like bulk density is |
|
| 26:52 | gonna work very well. You can that reflected in response to the |
|
| 26:57 | And our next big question is how I change bulk density in the |
|
| 27:01 | Which is what I'm really interested Good news is for the density |
|
| 27:06 | It's actually quite simple. And one the reasons uh this happens occasionally, |
|
| 27:15 | I'm only gonna run one log a of times they will make sure they |
|
| 27:20 | , they will simply the only, only porosity tool they would run is |
|
| 27:24 | density run. I don't think that's much true destiny and Neutron to run |
|
| 27:29 | often together. And I don't think a huge additional charge we're running the |
|
| 27:35 | Trump on that. So let's look the final possible biology effects now, |
|
| 27:43 | we have to deal with, So basically the idea here is |
|
| 27:49 | uh why can I tell uh water oil which densities aren't that much different |
|
| 27:55 | the densities? Of course, K do because there is that big |
|
| 28:03 | I really cannot tell oil from the , but I can tell rock |
|
| 28:11 | Yeah, it's, it's simply about , went through that probably an order |
|
| 28:17 | magnitude more sensitive to the rock. the other thing I would get out |
|
| 28:24 | . This is, these are numbers should remember is 265 calite, something |
|
| 28:33 | 2.7 and dolemite and what you call , it depends on how do or |
|
| 28:40 | is, right? So it can from something. It's barely Doma the |
|
| 28:47 | dot They range from 2.8 to 2.8 5. So they think that |
|
| 28:54 | So those are numbers you should remember because they were probably played quite a |
|
| 28:58 | to try to interpret and understand what mean and what the correct. So |
|
| 29:05 | will feel free to ask you those numbers the same probably are already |
|
| 29:16 | And the other thing you can see how low gas in it made. |
|
| 29:19 | gas has a even though it's more to for because that number is so |
|
| 29:27 | and vero estimates are based on the that your density log indicated density of |
|
| 29:35 | in order, right. Number one significantly lower. So you will then |
|
| 29:43 | sort of direction leading up to the gas have on it? I cross |
|
| 29:49 | rate too high or too low. too. So that gets easier once |
|
| 30:02 | get to the. But basically what is you're not measuring enough electrons, |
|
| 30:09 | you replace the core fluid? It's the to build with a fluid. |
|
| 30:15 | you're not measuring enough electrons and it that, that basically not enough |
|
| 30:21 | So it thinks the F is higher it is, are they OK? |
|
| 30:29 | it's measuring? This is a big to remember what the effect of gas |
|
| 30:33 | on the tool. One of the uses of the density, along with |
|
| 30:37 | neutron, you look for gas, salt is pretty high. The other |
|
| 30:47 | you might want to pay attention to coal. This will help you later |
|
| 30:52 | the exercise and we're gonna run But remember what the density of |
|
| 30:56 | It, it's love. So here's correction chart. Now that we're experts |
|
| 31:07 | the density tool, there's lots of we can them. So one of |
|
| 31:12 | actually, I was curious about this not, but it always gets |
|
| 31:17 | Exactly correct. Why would that Nature? Loves the line of |
|
| 31:26 | Yeah. Loves the limestone. That's a better answer. The limestone lies |
|
| 31:34 | between 272652.8. Right? So if going to minimize the corrections, you |
|
| 31:41 | , you would correct relative to the . So they force the tool to |
|
| 31:47 | correctly in limestone. One interesting feature this, another interesting feature of this |
|
| 31:57 | what happens to the magnitude of the as my ferocity gets smaller, then |
|
| 32:05 | direction intercity is zero. This is . It's pretty close to as high |
|
| 32:12 | you can. What happens to the of my correction away from limestone blinds |
|
| 32:19 | separating from limestone? Yeah, that sense. Does it make sense? |
|
| 32:29 | have to chart charts, correct. what happens is the process gets |
|
| 32:39 | I get more rock. So the of the rock is gonna get |
|
| 32:44 | So my corrections will get large as grass gets smaller. And what are |
|
| 32:51 | doing here? This is the magnitude the correction, right? As I |
|
| 32:57 | replace poor fluid with gas, This is gas in the poor |
|
| 33:04 | So what's the magnitude of that correction to the li correction? Huge? |
|
| 33:12 | ? So there is a significant gas on this tool. We already discussed |
|
| 33:18 | or make it across here too right? What's the magnitude of the |
|
| 33:23 | effect when the vero is zero Right? There is no force space |
|
| 33:33 | put gas in. So there's no , the correct force. So you |
|
| 33:37 | get, so your gas effect gets as the porosity gets bigger. |
|
| 33:43 | She also sent everybody. Ok. , and you might wanna look over |
|
| 33:49 | at collar or collar, it's gonna you with the exercise and not too |
|
| 33:55 | . One question, anything else we look at kind of solve its way |
|
| 34:03 | the line. So it's gonna be to solve. How do we get |
|
| 34:11 | from this? What could be This is a volume weighted average. |
|
| 34:17 | all we take it's weird averaging the amount of more of the density |
|
| 34:26 | the fluid, the volume weighted right? So eight times the density |
|
| 34:33 | gives me gives me a an amount four fluid. This is the amount |
|
| 34:38 | matrix that gives me the density, ? So if I know this, |
|
| 34:42 | know this, I can solve this for this should shouting up things to |
|
| 34:50 | . One is it's a simple This means that the different components are |
|
| 34:56 | interacting with each other, right? it it's very simple. Again, |
|
| 35:01 | is electron scattering. So it's a local effect. You have a gamma |
|
| 35:05 | scattering off an electron doesn't care whether another electron here. Here, here |
|
| 35:11 | a very local effect. So that simply a simple sum of the amount |
|
| 35:16 | electron that we have. You're not get such a simple uh response out |
|
| 35:22 | the neutron and we sure are not get the simpler response out of the |
|
| 35:28 | and the components interact with each So people have to do my car |
|
| 35:34 | , for example, to calibrate the acoustic, people still want to really |
|
| 35:40 | how to calibrate it with biology So we're OK with this, which |
|
| 35:47 | be expected to remember this a simple weighted average rate. So those are |
|
| 35:55 | volume weighted average. She takes the of fluid plus the volume weighted average |
|
| 36:02 | , right of the matri the bulk I simply. So the that I |
|
| 36:07 | have think 23 that's a great That was the question I was gonna |
|
| 36:14 | you, you now know enough the response is so simple that how |
|
| 36:21 | we account for gas in the forest ? It's gonna ro matrix. |
|
| 36:30 | Is it gonna affect about fluid? , but it will affect, |
|
| 36:34 | Is the assumption that mentioned is that four space is completely filled with |
|
| 36:41 | So what's gonna happen is I will to correct for the amount of fluid |
|
| 36:47 | the amount of gas that will be weighted simple volume, weighted average of |
|
| 36:52 | fluids, right? The density of fluids would be I would substitute he |
|
| 36:59 | , I'll show you the break but it's, it's a simple correction, |
|
| 37:04 | least in terms of that which the log by the way is not nearly |
|
| 37:09 | simple. So here when we solve , because the equation get sure you |
|
| 37:20 | all do that algebra and you can the the real unknown here, I |
|
| 37:25 | this, I usually know my fluid like I said, it's not very |
|
| 37:29 | to the fluid other than if you gas instead of this, then there's |
|
| 37:34 | significant density difference of one thing, ? So it will matter. And |
|
| 37:39 | showed on the chart and I, I already mentioned, we get this |
|
| 37:43 | matrix, we often will even better us to, to know what the |
|
| 37:50 | does, right? So to get right ferocity which we really care |
|
| 37:55 | right? Why do we care about the ferocity? Right? Spent a |
|
| 38:02 | amount of time in the course up now, it's about volumes. It's |
|
| 38:06 | about how much hydrocarbon do I So if I'm off by 20% ferocity |
|
| 38:14 | , I'm off by two ferocity That's 10% for that billion barrel |
|
| 38:21 | But you care about that. you would um could be a lot |
|
| 38:25 | money. So it's worth spending the to calibrate that. But a lot |
|
| 38:30 | times, for example, the play here is mostly gonna be a grain |
|
| 38:36 | for them. So if I want calibrate that I would want to know |
|
| 38:40 | if I have be bar, which significantly lower brain density than works. |
|
| 38:46 | would want to know that maybe there's way I could get the amounts of |
|
| 38:51 | other minerals. P is a you know, the is so |
|
| 38:56 | So I would like to predict the of P you need the brain tell |
|
| 39:03 | it really does matter calculation that we that number well with that. But |
|
| 39:10 | have certain things we would like to , fair enough. So that's, |
|
| 39:18 | know you need to know from the can say off from the court. |
|
| 39:23 | need to know what's going on, . With our fluids, particularly |
|
| 39:28 | That's what the log measures. here's, here's the numbers 2652.78 0.85 |
|
| 39:38 | fluid density you can see really don't that much, right? So we |
|
| 39:44 | usually use, have a fairly good . Yeah, this thing is only |
|
| 39:48 | a few inches in the bo it's invaded to that depth. So we |
|
| 39:54 | be using the density of our blood right, right formation, completely |
|
| 40:04 | So it's fairly simple to calculate what correction is. High carbon density. |
|
| 40:11 | again, that's top oil base. again, we would just use our |
|
| 40:15 | to, to really get about Right. And like I said, |
|
| 40:20 | don't have to prevent the density, them what grade density to use is |
|
| 40:25 | trivial calculated process. So this is a graph. Nobody ever thought |
|
| 40:38 | right. This is back maybe when have calculated rather than calculators, they |
|
| 40:44 | use it to slide rules. Uh might do this but it it does |
|
| 40:48 | you kind of interestingly enough a right? If you have a measured |
|
| 40:53 | density and what your variation and cos be right based on uh whether I |
|
| 41:00 | something like a dolemite, a limestone a sandstone here, dolomite here, |
|
| 41:06 | ? So two points, right? this is basically a plastic here. |
|
| 41:11 | a dolemite. How much air and am I gonna get? Yeah, |
|
| 41:17 | you do is go up here and over to this axis. So if |
|
| 41:21 | were doing, if I were using limestone rather than a dolemite, well |
|
| 41:27 | my air and porosity five, That isn't the right. So you |
|
| 41:37 | to have a little get significantly wrong and then this just gives you the |
|
| 41:49 | fluid correction, which is relatively minor correction for reasons that we've talked about |
|
| 41:58 | OK with it. It normally comes charge. And then this is the |
|
| 42:06 | you asked about how do we grab gas? And then we just take |
|
| 42:10 | raw fluid. We're gonna write that a weighted average that it's weighted by |
|
| 42:15 | saturation now, but it's simply a of the core fluid that will |
|
| 42:22 | So I want to have the density my unrate science, my flesh |
|
| 42:27 | right, water saturation and hydrocarbons and whatever I right. So gas as |
|
| 42:39 | figured it out looks like an increased velocity and then we would just do |
|
| 42:44 | weighted average. And this is what would plug into the density equation. |
|
| 42:48 | show a little bit earlier. It is pretty straightforward to Children. What |
|
| 42:58 | the clay effect be on this Already mentioned that back, every |
|
| 43:12 | this is part of the reason we uh the way we show in order |
|
| 43:20 | calculate a play effect, I need know the grain density of the |
|
| 43:26 | OK. In order to get that density, this is a common misconception |
|
| 43:33 | the industry. If you go look , go into the literature, look |
|
| 43:38 | the look up the density of smack , right? And you will find |
|
| 43:44 | all over the place ranges from like to 2.8 or something like that. |
|
| 43:52 | is that? Well, it's, actually that would be a much better |
|
| 44:02 | get that variation than the one. really true. I actually, I |
|
| 44:05 | a student allocate this. Right. I have spec particularly, particularly bad |
|
| 44:11 | it has such a high fat, exchange capacity. It has such a |
|
| 44:15 | amount of water. So, depending how dry it is, it will |
|
| 44:23 | if it's like hot. If if it's equilibrated with use and |
|
| 44:28 | you'll get something more like 2.42 If you put it in a vacuum |
|
| 44:33 | at 60 degrees C, you will something more like 2.7. And |
|
| 44:39 | depending on the condition, how much water. So what do you want |
|
| 44:44 | use? Which of those green densities you be using to calculate a porosity |
|
| 44:51 | a porosity correction? 2.4 or the ? It is actually a fairly subtle |
|
| 45:03 | . I, this will lead up what we're gonna, we're gonna change |
|
| 45:09 | definition of veracity another hour or that's amazing. I agree with the |
|
| 45:19 | . So given that, that the is exactly right. Why I can |
|
| 45:31 | it's actually because you're, you're exactly , you want to use the |
|
| 45:37 | It's because we are gonna call the total water content of the |
|
| 45:44 | So this is because basically this definition based on the neutron tool which we're |
|
| 45:49 | talk about in a second that is incorrectly all the time. I'm gonna |
|
| 45:57 | you to do this in the exercise . I would like you to calculate |
|
| 46:04 | and you get shales it with, know, in class exercise you're gonna |
|
| 46:15 | . All right. So that, answer will make a little more sense |
|
| 46:18 | a bit actually. Uh, the density for a gas, right, |
|
| 46:26 | fluid by the thing uh is actually an interesting question. It could vary |
|
| 46:31 | significant amount. And so yeah, could see the specific gravity who will |
|
| 46:38 | on depth, for example. Uh so you need to, to have |
|
| 46:44 | PV T properties get this exactly Right. It, it is significantly |
|
| 46:50 | than oil or water, but how lower, right, depending on what |
|
| 46:56 | on what the pressure is, what temperature is is after. And because |
|
| 47:01 | methane and gasses are not ideal right. Can I use the ideal |
|
| 47:07 | law? So you, you really to have the PV T that |
|
| 47:16 | it makes our life a little more . So the spectral density, so |
|
| 47:22 | already saw even for the density which is the least Liro log. |
|
| 47:30 | . Uh we would love to know the li is. It actually innovation |
|
| 47:36 | in while I was in the interview it was a significant help with interpreting |
|
| 47:43 | . That was the idea that we're from a scattering and they compensate neutron |
|
| 47:48 | CN, right? And they compensate neutron log, we don't have |
|
| 47:55 | There is a significant effect. But with only that tool, right, |
|
| 48:00 | , you saw it was porosity dependent correction, it's gas dependent. All |
|
| 48:04 | these things come into play. So have a difficult time getting the li |
|
| 48:09 | of, of that tool alone for . OK. So what they |
|
| 48:15 | so quite a idea, you look the low energy spectra right of the |
|
| 48:22 | ray when it absorption comes into play absorption is basically the bulk of the |
|
| 48:31 | , right, usually uh causing the , right. So uh this will |
|
| 48:37 | you much better li information. So you actually measure is the volumetric photo |
|
| 48:45 | or fish. So that's this u you're measuring is related to this photoelectric |
|
| 48:51 | section that introduced just a second ago an electron. So this photoelectric cross |
|
| 49:01 | is ultimately what you would like to . But that's the one that determines |
|
| 49:06 | the li is. So we have go from this absorption measure what the |
|
| 49:12 | of the gamma rays have we actually , the right have we absorbed and |
|
| 49:18 | to uh to this number to show that's a correlation. But uh I'll |
|
| 49:23 | you in a second why would be be such a disaster for this good |
|
| 49:31 | that he has such a high density with it. So he will get |
|
| 49:35 | dominant So if you have a bear mud, this tool becomes much less |
|
| 49:46 | , she's probably not gonna talk to . So this pe curve is a |
|
| 49:52 | section is a characteristic and extensive property the rock, which is gonna tell |
|
| 49:59 | what kind of rock it is. is an extensive property, right? |
|
| 50:05 | on how much we actually absorbed. we need that. Here's that correlation |
|
| 50:13 | talked about, right. So we this, we could go with that |
|
| 50:18 | kind of a bulk density that we right, that an interpreted density, |
|
| 50:24 | this key value is. So what displayed for you with the photoelectric |
|
| 50:33 | literally this is a correlation. So kind of a look at kind of |
|
| 50:42 | the energy dependence of this out here doing content scattering. This is where |
|
| 50:46 | CNL operates at measuring right uh gamma at this energy. When we get |
|
| 50:54 | the low energies when we can do case shell or rate absorption kick out |
|
| 50:58 | K shell electron, right, we get varying varying amounts of the photoelectric |
|
| 51:07 | . And then we can actually go and interpret a a interpret tool based |
|
| 51:12 | the spectrum et cetera or what my curve is. So this demonstrates there's |
|
| 51:23 | lot of points about the curve. is my photoelectric cross section here. |
|
| 51:28 | you can see how different quarks from from calum is right. The other |
|
| 51:34 | I want you to notice is how these curves are. For some |
|
| 51:39 | they folded this, I guess to it to fit into a smaller |
|
| 51:43 | But we start with uh my total uh whatever I measure here and, |
|
| 51:49 | then I reflect off of this. over this large range, right, |
|
| 51:57 | measured porosity, this curve is nearly . So it really doesn't matter what |
|
| 52:02 | measure here very much at all independent porosity because these curves are vertical. |
|
| 52:09 | see that no matter what porosity I in with all the from 0 to |
|
| 52:15 | , I go to electric cross It's changing from below her five to |
|
| 52:18 | little less than five, little bit of an effect. Whether it's uh |
|
| 52:25 | with gas also is the gas effect independent of whether there's gas or it's |
|
| 52:32 | or not. Uh I, I less of, I, I don't |
|
| 52:36 | very much of an effect. I have a gas effect. I don't |
|
| 52:40 | a porosity effect. So this is great tool for determining the li you |
|
| 52:46 | anybody see that and again, the change in larger numbers, right. |
|
| 53:03 | . Gets the, the percentage change bigger and bigger ferocity. Since you |
|
| 53:08 | try the high ferocity, think that's you and you have a larger volume |
|
| 53:18 | the fluids which are replacing the gas like. But at the same |
|
| 53:28 | Yeah. OK. This is the point you're gonna have something you're really |
|
| 53:34 | need when I give you the I might tell you what it is |
|
| 53:39 | . So we're gonna give you a and squared log, we're gonna give |
|
| 53:42 | a bud log and you're gonna go and use those tools, right? |
|
| 53:47 | the log neutron porosity, the density et cetera. You're gonna identify the |
|
| 53:55 | we have to get through the new log and acoustic logs before we can |
|
| 53:59 | done, but it probably be after and it will be after function. |
|
| 54:05 | everybody sees the value of the pe , almost the direct li indicator, |
|
| 54:14 | fun ferocity changes. And so this interesting to look at right, what |
|
| 54:25 | pe value are now, right. Calcate is five versus three versus |
|
| 54:31 | Salt is actually quite large and look these heavy minerals, cite iron |
|
| 54:38 | I right looking for be right, . You can now see why small |
|
| 54:44 | , variable amounts of, right, devastate your ability to use this |
|
| 54:50 | Yeah. How about what you guys have significant significant amounts of iron associated |
|
| 55:02 | them. So iron is actually a heavy mineral. You see what happens |
|
| 55:08 | pide, it's dominated by iron. iron and clay also make. So |
|
| 55:14 | you go through this exercise and your curve is not making sense, you |
|
| 55:20 | that the data is bad can, it wouldn't be correct. It probably |
|
| 55:27 | you an indication that you have a effect, not gonna deal with. |
|
| 55:34 | bye. Places will make offer for . So heavy minerals are this nemesis |
|
| 55:47 | this is basically the the first are OK with that? And you can |
|
| 56:01 | how low it is for water, and, and that was the |
|
| 56:13 | So a couple of examples here on tool, you've plotted this porosity based |
|
| 56:21 | a limestone matrix. So what does mean? That means that in a |
|
| 56:28 | , the velocity will be correct. in a dolemite, right, it |
|
| 56:34 | not be correct. So in a process is gonna read too high or |
|
| 56:40 | low denser, it's gonna have more gonna interpret that as more rock. |
|
| 56:49 | it's gonna get, where is it a, if we have quarts instead |
|
| 57:00 | limestone, it's gonna have the opposite , right? Let's go ahead and |
|
| 57:06 | at what's going on in this log , right? So in a |
|
| 57:11 | right? Yeah, we, we , if you look at what we |
|
| 57:15 | , we have this is my pe . If you look at the value |
|
| 57:19 | my pe E value, what? a little bit less than five back |
|
| 57:27 | look here. Where is that? look at cal site, it's probably |
|
| 57:33 | five immediately say gee this is in range that looks like a limestone. |
|
| 57:41 | the velocity here should be correct about here right down here here. My |
|
| 57:56 | reading the lower value. It's like two things. That's the that right |
|
| 58:10 | and across process is gonna read correctly , it's gonna read incorrectly in other |
|
| 58:19 | . Right. We immediately know that should be calculating that cross in the |
|
| 58:26 | way. But if I know it's sandstone, I, I know what |
|
| 58:29 | desk we use and I know how calculate the process here. Right. |
|
| 58:37 | in between, we know what that . Is that a dolomite do about |
|
| 58:57 | . It's not that far. Really is we cannot unambiguously interpret that because |
|
| 59:09 | could be a, a cemented sandstone a significant amount of cal cement |
|
| 59:19 | Let's nominally global light. So we another log to do that. And |
|
| 59:26 | have two measurements here, right? I have three unknowns. So it |
|
| 59:31 | be there are other combinations of these two of the minerals that could cause |
|
| 59:37 | . Are you OK with that? gonna be the basis of your answers |
|
| 59:49 | , well, there's two end right? If I'm only allowing myself |
|
| 59:53 | minerals, sandstone by limestone, I can't get above limestone, I can't |
|
| 60:02 | the low a class of importance. those two somewhere in between could be |
|
| 60:10 | average of one another. So in, in general your life, |
|
| 60:19 | , we'll see this. I can't , I can't average 53 or, |
|
| 60:30 | for example, I, I can't a limestone and that we can |
|
| 60:39 | I cannot, sorry, cannot average times can average a three and then |
|
| 60:48 | two, get a five. It just simply a linear addition, no |
|
| 60:55 | how I wake three and two and it makes them add up to five |
|
| 61:03 | . I'll, I'll, I'll show that. Well, it, it's |
|
| 61:14 | , I'm gonna measure pe value, gonna try to interpret it based on |
|
| 61:17 | pe value what the mineralogy is. pretty sure. I mean, there |
|
| 61:23 | things, for example, if I or I had pr, or something |
|
| 61:27 | that I could get a sandstone quite . But I, if I, |
|
| 61:32 | I had significant amounts, if I significant amounts of writing, right, |
|
| 61:38 | could average 17 and two and I get to, I could, I |
|
| 61:43 | get to the survive and it wouldn't that much to take that half. |
|
| 61:51 | that, that's the whole difficulty and , you're gonna spend a fair amount |
|
| 61:55 | time this afternoon worrying about exactly this of thing. How do I, |
|
| 62:02 | do I interpret? Yeah. Which things? Oh, that's a |
|
| 62:22 | Yeah. So five, it was little bit less than five. The |
|
| 62:27 | , you know. Yeah. we look at the values, |
|
| 62:31 | Gold mine was a little bit over , was a little bit under |
|
| 62:36 | And then that's where those are the pi are simply those numbers just |
|
| 62:41 | give you some mythology indicator. that would be one thing I would |
|
| 62:55 | in. So, so again, thing, uh, place will often |
|
| 63:04 | iron and other things associated with So you put it up uh based |
|
| 63:10 | that and, but the, the is that's so variable in a |
|
| 63:15 | It's really hard to want, want play that. So it could be |
|
| 63:25 | 50 do my limestone, it could 70 30 limestone sandstone. So |
|
| 63:32 | it could be a combination. Here's look this chart again, I want |
|
| 63:38 | to notice how vertical these lines are very small. This is the bulk |
|
| 63:43 | on this axis, right? You calculate lines still and ferocity if you |
|
| 63:48 | on this axis. But just the of what my bulk density would |
|
| 63:53 | So my peak or right, basically much difference there would be. The |
|
| 63:59 | thing about this is it showed the how we are going to average these |
|
| 64:04 | , right? We're simply going to a linear average between different biologs. |
|
| 64:11 | suppose I had a pe value of and we assumed that it was a |
|
| 64:17 | of calite and quarts that would indicate we would simply move along this |
|
| 64:26 | right? It it's like, this is my pe value. This |
|
| 64:32 | my here, this is a response curve for calcite. This is a |
|
| 64:41 | curve for this is a porosity curve quartz. And so if I have |
|
| 64:48 | of these things, for example, I have a mixture, in this |
|
| 64:52 | of calcite and quartz, it simply get the relative fraction of these, |
|
| 64:57 | guess linearly and interpolate along this But this one, in fact, |
|
| 65:02 | need something like mostly Calci, Actually, um so again, the |
|
| 65:11 | here is the responses. So this closest to Calite, it's dominated by |
|
| 65:16 | . This is your 70 30 dance you get these points are examples of |
|
| 65:26 | of a pure mineral. This is I was trying to say about the |
|
| 65:30 | there, there is no way if lie here, there's no way I |
|
| 65:34 | average this and this right and end here, I have to lie somewhere |
|
| 65:41 | between two. So if I lie this line and I know I only |
|
| 65:47 | these three minerals as possibilities, I to have calcium, right? If |
|
| 65:55 | , I'm off the line, I be adding like moving towards dolomite and |
|
| 65:59 | towards I, I could have some of dolomite. I would have actually |
|
| 66:04 | relatively smaller branch of cords to get as I move along this line. |
|
| 66:12 | would be a mixture of. So I move along this line, |
|
| 66:18 | Getting more and more reports until I 100% here that OK with everybody, |
|
| 66:29 | one thing. So it's very good telling him the these lines would represent |
|
| 66:34 | of cal and do or a mixture dolemite. What fraction of the, |
|
| 66:41 | me how much couple of things On a note like the line is |
|
| 66:50 | entirely vertical, very small variations in pe curve. It would cause huge |
|
| 66:56 | if interpreted fall down talking about the not get porosity from this relatively |
|
| 67:07 | insensitive velocity. It's insensitive to That's its strength. If I, |
|
| 67:13 | I could go and get a ology , that gets kind of independent of |
|
| 67:17 | other, the first place I go get Liz, probably this curve if |
|
| 67:23 | add it, have it. If then look at my other logs and |
|
| 67:27 | find they're inconsistent with this. One the first thing I'm thinking not bad |
|
| 67:33 | and no, I'm not doing it . Maybe I have a claim. |
|
| 67:41 | . So you can see I can this as Calite. No way to |
|
| 67:44 | any dolemite quds in in there. has to be quartz. I'm at |
|
| 67:51 | , I'm at an extreme anywhere else have a combination. This one could |
|
| 67:57 | a mixture of Calite and Boite. roughly 50 50 or this could be |
|
| 68:03 | mixture of calite and quartz, uh calci something like 32% closer to the |
|
| 68:17 | , measure the length of two lines calculate that all. OK. With |
|
| 68:24 | , this is basically a summary of strengths of this tour gas effects the |
|
| 68:35 | density but not. So the gas here is simply to move this. |
|
| 68:40 | if you have gas, if you it here and the blood biology, |
|
| 68:43 | makes sense, right? This uh affect this, but it still doesn't |
|
| 68:47 | the, it just gas to the be ok at this time. Right |
|
| 69:01 | more. Um, so there, know, there's various everybody's got |
|
| 69:08 | So you're gonna get curve and we for an hour and a half into |
|
| 69:19 | already. So I guess we'll take break and then we'll come back and |
|
| 69:23 | about the new trial more fun because a little more complicated and we have |
|
| 69:32 | most fun that we don't talk about acoustic quality. We see them, |
|
| 69:38 | see how long it takes finishes the . Then we have an exercise, |
|
| 69:51 | then uh compensated is gonna come into . Uh CNL stands for compensated neutron |
|
| 70:01 | and then we have uh thermal versus the mal the idea of scattering versus |
|
| 70:07 | is also gonna come into play. , some of the ideas we've already |
|
| 70:12 | , right. Again, it's uh actually uh pushed up against the borehole |
|
| 70:18 | wall just like the density tool this with, without a man, |
|
| 70:24 | The other one had a man that it against them. So you actually |
|
| 70:28 | a caliber. So you've got some as the corrections were so important. |
|
| 70:34 | then we're gonna have basically the same interactions that we're gonna have scattering, |
|
| 70:40 | are these elastic eli collisions above the energy level. That's gonna be the |
|
| 70:46 | thermal tool, by the way, your epidermis your outer layer, |
|
| 70:53 | So, uh that's gonna be scattering that's gonna be less lithic dependence than |
|
| 70:59 | capturing absorption neutron. OK. They very same ideas, very same effects |
|
| 71:05 | with the density and the lit the to. All right. I remember |
|
| 71:10 | this came out too, it was silver bullet. We were gonna never |
|
| 71:14 | to cut another cord again. But was the logging company's advertising back. |
|
| 71:20 | actually work out. Those are the ideas we have switch on laser |
|
| 71:36 | So what's the life of a neutron ? So you actually have a source |
|
| 71:41 | neutrons and we'll talk about the two . We have a radioactive source as |
|
| 71:45 | as we have a neutron generator. to me always amazed me, |
|
| 71:50 | what the the oil industry could do a portal, everything from an NMR |
|
| 71:55 | neutron scattering like ponding, right? what happens is actually the tool emits |
|
| 72:01 | high energy neutron. This bounces around a while, right, randomly scattering |
|
| 72:08 | into the formation, then it gets a low enough energy. This is |
|
| 72:14 | , right? Basically with the First concept, we have to have |
|
| 72:23 | of the most important is what is to slow this neutron down the |
|
| 72:29 | So sure most of you have at seen pool on T VA lot of |
|
| 72:34 | have probably played. What happens if bounce the cue ball up a |
|
| 72:39 | it comes back with essentially the same . However, with a single |
|
| 72:44 | you can completely stop the cue right, hitting another something with an |
|
| 72:49 | mass. It all has to do conservation of mass. In principle, |
|
| 72:54 | should have worked through this in your school physics class. But this tool |
|
| 72:59 | going to be most sensitive to So protons because they are almost identical |
|
| 73:07 | with a neutron to provide a mass an electron give or a day. |
|
| 73:14 | . So what are we measuring We are not measuring electron density electrons |
|
| 73:19 | little tiny things which would bounce off thing and barely notice it wouldn't slow |
|
| 73:23 | down at all. You're measuring hydrogen . The good news or the bad |
|
| 73:33 | is that the hydrogen density in oil quite close to the hydrogen density in |
|
| 73:40 | . So you cannot tell oil from with this tool, but I am |
|
| 73:46 | measuring the amount of water very different the density tool densities, tools measuring |
|
| 73:56 | amount of rock, the neutrons tool measuring the amount of water. So |
|
| 74:01 | have basically all most of the questions ask about these tools will be the |
|
| 74:08 | back dramatically. For example, we can figure out what will be the |
|
| 74:13 | effect on this tool process measures too or too low, too low because |
|
| 74:19 | don't have enough water opposite of the tool, right? What what happens |
|
| 74:27 | the depths of investigation of the tool a function of porosity opposite of the |
|
| 74:35 | tool? Right? So again, more water you have, the less |
|
| 74:39 | depth of investigation will be OK. already we know most of the physics |
|
| 74:47 | could be easier, right? Then it's thermal and this is where the |
|
| 74:53 | is where we actually we are when we measure neutrons with these |
|
| 74:59 | we are measuring, this is the the mal tool that's measuring the higher |
|
| 75:04 | neutrons. When we get to roughly right by the 40th of an electron |
|
| 75:11 | , we now are measuring absorption and is the compensated neutron log which is |
|
| 75:17 | neutrons with this energy, right, is gonna be more lithograph dependent the |
|
| 75:26 | lower energy where things are getting For exactly the same reason with this |
|
| 75:34 | really is kind of right. So neutron is captured and gives off a |
|
| 75:39 | and captures Bob stated this is called slowing down length and it's just a |
|
| 75:49 | it uh typically travels to become thermal the definition of that slowing down |
|
| 75:59 | And then it starts to most that not diffusing here because it's not |
|
| 76:04 | equilibrated diffusion is a random process. actually has you're actually slowing things |
|
| 76:11 | So it's gonna move differently here than , but going down length versus a |
|
| 76:17 | length epi the mal up there, you stated, thermal energy compensated to |
|
| 76:24 | down there. So this tool is compensated obviously an old picture as a |
|
| 76:33 | how many detectors do we have. it's not compensated people, right? |
|
| 76:39 | would need another detector. This is and no, nobody runs the |
|
| 76:55 | So the problem with all of these tools are they were very li |
|
| 77:01 | They actually needed a calibration kind of the well site for sure. We're |
|
| 77:07 | to be doing that anyways. But because they had that effect, |
|
| 77:12 | Uh really hard to interpret quantity this , the first generation tool, it |
|
| 77:22 | a single detector. You looked for neutrons that capture gamma rays or some |
|
| 77:29 | of, right? And the problem that you had to know the highest |
|
| 77:34 | lowest porosity possible and then you just between those two. So you basically |
|
| 77:40 | to know the answer to get the , right. So uh the compensated |
|
| 77:46 | was a significant step forward. nobody runs these anymore. The only |
|
| 77:52 | maybe in some Russian logs a long ago, you might see some of |
|
| 77:57 | . But other than that, you really don't see them second |
|
| 78:02 | right? It's the sidewalk neutron et cetera. They came in in |
|
| 78:06 | sixties and they added a single epi mal detector. And then similarly, |
|
| 78:12 | had similar pro problems with this, ? How, how do we calibrate |
|
| 78:17 | ? How do we quantitatively interpret Right. And then we ran into |
|
| 78:23 | generations, we had a para So a compensated tool in the seventies |
|
| 78:29 | created me. Then I do remember this one came in, right where |
|
| 78:34 | had a pair of thermal neutrons, had a pair of epi thermal neutron |
|
| 78:40 | . And this is when they gee, we've solved all problems. |
|
| 78:44 | . Because we have something that's relatively , independent, lithp dependent. So |
|
| 78:50 | could do all this cool stuff Yeah. It's like this, this |
|
| 78:57 | bullet where people are not gonna have make any core measurements anymore that it's |
|
| 79:02 | turned out to be true. The one was which will show you when |
|
| 79:08 | take the lab to. It doesn't any of these are not useful. |
|
| 79:12 | are just not the panacea things always oversold by the way, which is |
|
| 79:19 | happening. The data analytics right it's getting oversold. It was not |
|
| 79:23 | silver bullet to answer all questions, it will be a useful. |
|
| 79:31 | So the the thermal means that there's lithic effect again, because there's an |
|
| 79:39 | here. This is scattering dominated Jim stayed in. And then this one |
|
| 79:48 | actually quite cool uh this generation tool at that reason, 30 years old |
|
| 79:55 | , but they actually have a down neutron source, right? An |
|
| 80:01 | Why would it be worth all that ? But answered this question because that's |
|
| 80:07 | to actually build a down hole neutron . That's a really complicated thing to |
|
| 80:13 | on you, right? And why would you go to all that |
|
| 80:20 | ? What happens if I stick this them do not have a radioactive |
|
| 80:26 | Right. So there's much less hsne for this thing. Right. In |
|
| 80:33 | , I could grind this up even it would be expensive, it's less |
|
| 80:38 | than actually having to plug back and track it. Yeah. So I |
|
| 80:44 | this is fairly commonly won now. . So it's not, this is |
|
| 80:48 | tool. I probably still wouldn't straddle the rig floor, but uh it's |
|
| 80:54 | always actively admitting new trials. So tool, I won't even bother to |
|
| 81:00 | you that anymore. You actually have moderation phase, slowing down length we |
|
| 81:05 | about, then you have a fusion . And so the relative intensities of |
|
| 81:11 | gives us a much better, This ratio of these gives us a |
|
| 81:15 | better estimate of neutron porosity. Why it worth building this entirely separate |
|
| 81:24 | We already had the density tool easy interpret. Why do we wanna go |
|
| 81:29 | and do this, spending all this developing it? You talk to |
|
| 81:35 | for example, they even tell you 10 years of R and D, |
|
| 81:38 | new tool they develop takes them roughly years of R and D to get |
|
| 81:43 | out to market. That's not a amount of money. Again, we'll |
|
| 81:50 | the answer here is that the one the rock, this one measures the |
|
| 81:55 | . So they have dramatically opposite porosity effects and things like that, |
|
| 82:09 | ? No. So they epo the , which means their energy is higher |
|
| 82:14 | a thermal. So, out here where they're thermal here is where |
|
| 82:23 | they're, they're emitted with a higher than a thermal in. Ok. |
|
| 82:31 | on. And so we just get sim different and the near detector bar |
|
| 82:38 | , we get different amounts of Right. That ratio is, is |
|
| 82:43 | we really want to know. here's a look at the ology effects |
|
| 82:48 | , right? And uh again, think you can look and what's the |
|
| 82:54 | of having a sandstone versus a limestone a dolomite? I don't know, |
|
| 82:59 | just look at a lot of right? It uh 10% ferocity gonna |
|
| 83:06 | my count rate is significantly different depending rock, right? And they're scattering |
|
| 83:15 | off the uh hydrogens. Will there a clay effect on this tool? |
|
| 83:24 | it's not found water. There are groups associated with the clay matrix. |
|
| 83:30 | so what would happen is we would there's extra hydrogens around. So that |
|
| 83:38 | act like additional water. So this make the porosity, right? Places |
|
| 83:45 | make the porosity read too high because these uh inter crystal and oh groups |
|
| 83:55 | the clay matrix, the clay we all OK. With that, |
|
| 84:01 | can see there's concrete gets affected, what that has on that. And |
|
| 84:10 | the compensated neutron log, it's a , the near fire detector counts, |
|
| 84:14 | have two detectors, it's calibrated uh using test pits. Each mythology has |
|
| 84:22 | own bulk density and cross section sigma capture cross section sigma and its own |
|
| 84:28 | versus crossing. So this is not simple because there are multiple scatterings, |
|
| 84:36 | ? And it it's not the simple that you have for the density |
|
| 84:41 | you have to know the lithograph and pos right must contain the liquid to |
|
| 84:46 | a proper porosity. So there's a , that's the thermal, the truck |
|
| 84:53 | cross cross engine to set. It's probability that you'll thermal. Here's an |
|
| 85:02 | , right? This is a this is basically a porosity recorded using |
|
| 85:07 | limestone matrix. Again, they assume that's the one they want to correct |
|
| 85:12 | from. You can see that dolemite uh on the opposite side from a |
|
| 85:18 | . The dashed curves are and you read it here but ignore that for |
|
| 85:23 | minute, which would be to cover up too. Sorry, wait, |
|
| 85:28 | is gonna be the CNL, the curves or the dash curves would be |
|
| 85:32 | CNL. I can ask you Even though it's stated here, you |
|
| 85:37 | see the CNL if you look if have a limestone porosity and you interpret |
|
| 85:43 | and if it's a dolomite, you're gonna get a ferocity, the |
|
| 85:47 | neutron ferocity, right? Something like . So what happens here? |
|
| 85:53 | Is I'm gonna get the uh property would record, right? If I |
|
| 85:59 | it was a limestone be something like if it was a dolemite, uh |
|
| 86:06 | coincidentally. And for exactly the same as the density log, you notice |
|
| 86:10 | nice straight line that goes through the to 1 line, right? You |
|
| 86:14 | get the right answer in limestone. because of the way the tools |
|
| 86:19 | right? And then for a So difference between dolomite sandstone, |
|
| 86:26 | For the CNL, which is the lithic is something like the difference between |
|
| 86:33 | porosity and 18% porosity. Do we ? Clearly, I backed her up |
|
| 86:42 | . So we really need to get ology correct for this tool. And |
|
| 86:48 | you notice the solid lines which are epi the tool, the side wall |
|
| 86:54 | porosity tool is the acronym for the tool. I mean you can see |
|
| 87:01 | difference between this is smaller. So have a smaller lithograph effect S MP |
|
| 87:07 | I do the CML for reasons I've we're all OK with that, assuming |
|
| 87:21 | no questions, I will assume that all understand perfectly. Yeah. |
|
| 87:31 | OK. Compensate a new law that the thermal neutrons, that is the |
|
| 87:41 | has an absorbed neutron component that has larger li of packing. So there's |
|
| 87:51 | cross sections. The the reason this is so effective is that the capture |
|
| 87:56 | section depends on li it's just the of absorption of a neutron, right |
|
| 88:04 | gets absorbed by the nucleus, So that's related to the biology. |
|
| 88:11 | . OK. Or not not. . What do you want me to |
|
| 88:17 | about more side wall neutron process? So lih effect is measured by the |
|
| 88:30 | between here and here. So for , the example given here, |
|
| 88:36 | at least in this direction, the is gee we measured based on a |
|
| 88:42 | matrix, right? So I've calibrated tool for limestone, interpreted it as |
|
| 88:47 | it was limestone, it was actually , right? So based on |
|
| 88:52 | it's something like 14% ferocity. That's this value. If it was |
|
| 88:58 | Dolomite, CNL, you would measure . The actual true answer would have |
|
| 89:04 | 8%. If it was a the actual true answer would have been |
|
| 89:13 | . So more than a factor of difference, if you have the ology |
|
| 89:19 | , both of them are significant. sorry, what, how do we |
|
| 89:25 | what's right? Yeah, that's what exercise this afternoon is gonna be all |
|
| 89:30 | is, is to get what the lithograph is. So you don't have |
|
| 89:35 | information here. You just run this . Hardly anyone runs the CNL all |
|
| 89:41 | itself because there's such a large lithograph . So for example, great |
|
| 89:47 | Let's run a lit the density Then the lit the density tool will |
|
| 89:52 | me a limestone dolemite or plastic and I know how to interpret the cross |
|
| 89:57 | year much better. Once I know lit, I need more data. |
|
| 90:02 | tool is not, you know. . Right. Their argument was gee |
|
| 90:12 | I ran the epidermal tool and the , the SNP, the epi, |
|
| 90:17 | MAL tool and CNL, at the time, I would have different mythology |
|
| 90:22 | . And therefore I could untangle just this tool. Right. What was |
|
| 90:26 | on? The problem was it really work well enough to be quantitative. |
|
| 90:34 | still a lot of difference. There's varying degrees of ization. There |
|
| 90:39 | clays, there are other things complicated . You're gonna get a much better |
|
| 90:45 | for that. When we do the , it's after that some, |
|
| 90:51 | all your questions will be answered at point. At least if you ask |
|
| 90:55 | as I walk around, we will attempt to do a better job. |
|
| 90:59 | really like this exercise because it ties everything we're talking about this morning. |
|
| 91:06 | this is an important one to OK? And again, it's |
|
| 91:15 | right? So you can see even the CNL, it gets limestone, |
|
| 91:19 | ? The S and P gets right? If the whole world was |
|
| 91:23 | , there'd be no problem. It's . And then yeah, if you |
|
| 91:38 | it on a sandstone matrix, you could get pretty wrong answers going the |
|
| 91:42 | way. Right. That's, that's rest of the lines. So significant |
|
| 91:49 | effect is the bottom line here Now we get to talk about, |
|
| 91:54 | we had spine and ribs plot before were gonna get to look at kind |
|
| 92:00 | uh what the depth of investigation for tool is. I haven't talked about |
|
| 92:05 | logs yet, but what they use , yes, 50% actually, |
|
| 92:13 | Sorry. Use 50% for relativity right? So what do we |
|
| 92:18 | We have different mythology tools here, . We have the compensated neutron. |
|
| 92:24 | have the density tool here just to , right? You can see it |
|
| 92:28 | a shallower depth of investigation than the two. But what is this |
|
| 92:33 | Right is how what is my depth investigation of the tool for these various |
|
| 92:39 | ? We have to compensate a We have the epi the tool, |
|
| 92:44 | side wall neutron porosity, we have formation density. Remember we talked about |
|
| 92:48 | depth of investigation was four inches. exactly what this means is that 90% |
|
| 92:56 | the tool response comes from a depth than that, that's what this is |
|
| 93:03 | a cumulative, right? This is cumulative how much at each depth, |
|
| 93:09 | fraction of the tool response occurs from or or gamma rays that penetrate to |
|
| 93:19 | depth. So if you look at area under this curve, right, |
|
| 93:24 | get to 100% here at four 90% of the area under the curve |
|
| 93:31 | at four inches or less. Should be experts on this probably like |
|
| 93:37 | size distribution, right? It's kind a very similar idea. You can |
|
| 93:42 | that the side wall neutron porosity sees . OK. Then the formation density |
|
| 93:53 | . OK. I got that Uh Sorry, this is the compensated |
|
| 93:58 | . It's seeing the deepest, which sense. Sidewalk neutron ferocity is this |
|
| 94:03 | , right? And then the formation is this guy. It sees the |
|
| 94:10 | deep. Why would, why would compensate a neutron and have a deeper |
|
| 94:14 | of investigation? First, when the emitted, it's got a thermal. |
|
| 94:24 | you're measuring in that range to get sidewalk neutron porosity and that will scatter |
|
| 94:30 | deeper before it becomes thermal. And clearly, it has to see |
|
| 94:35 | right? As gives you basically, it's remains epi the right to about |
|
| 94:42 | to this almost eight inches and then uh thermal measurement occurs maybe at a |
|
| 94:49 | to about 10 inches. The other thing is they use 90% of the |
|
| 94:57 | it gives you the depth of Here. I will tell you for |
|
| 95:02 | tools, they use 50%. So can talk about why that is if |
|
| 95:09 | use 50% for this, I would you to look at what you think |
|
| 95:14 | depths of investigation of the tool You really want to quote to people |
|
| 95:18 | my depth of investigation is two Probably not again because right, my |
|
| 95:27 | cake can easily reach an inch, and a half. I would be |
|
| 95:31 | dominated. This is why it's such correction problem, right? Everybody understands |
|
| 95:37 | this is that we're gonna run into and it's gonna be even more important |
|
| 95:43 | resistivity tools when we talk about them week, fair enough or not see |
|
| 95:53 | heads nodding. So I will assume a sense we can move on. |
|
| 96:02 | . And this obviously would depend on porosity, right? I'm sorry what |
|
| 96:10 | J factor is simply this number that . So these curves are the J |
|
| 96:15 | curves. So the J factor is percent of the tool response occurs at |
|
| 96:23 | depth less than this value. So we move away from the bore, |
|
| 96:29 | right, 20% of the tool response in about the first one inch for |
|
| 96:34 | density tool. 40% again, maybe inch and a half, 60% pretty |
|
| 96:43 | , right? And so I don't , two inches, maybe 80% of |
|
| 96:47 | tool response 3.5 and then 90% of inches. Again, this just is |
|
| 96:53 | you your, your tool response, ? It's picking up answers as you |
|
| 96:59 | away from the borehole and what percentage its response occurs at what distance away |
|
| 97:06 | the boreal wall. For this this is like what fraction of the |
|
| 97:14 | have a size bigger than this, ? As you look at the cumulative |
|
| 97:19 | , right. Ultimately, it has go to one because the total tool |
|
| 97:24 | , right? Ultimately, you have get to the total to response just |
|
| 97:29 | ultimately, you have to get to uh the total number of grains, |
|
| 97:33 | the total grains, right? So just integrating the distribution is what you're |
|
| 97:39 | , right? Is that OK, really is an important idea and it's |
|
| 97:48 | be actually more important for resistivity tools here. And what would happen to |
|
| 97:54 | penetration depth as the porosity went Why did they quote this or? |
|
| 98:00 | ? 22% porosity log with this vary porosity. Absolutely. And so what |
|
| 98:10 | happen is the porosity got bigger? gonna happen to my depth of |
|
| 98:16 | mainly reacting to poor fluids. So my process gets bigger, my depth |
|
| 98:22 | investigation occurs which shift towards the Yeah, this is an important thing |
|
| 98:30 | know, right. So here like density tool here as was assumed when |
|
| 98:35 | talked about it, you really are the flush stone almost entirely, |
|
| 98:40 | And, and for the for the density, right? Compensated density |
|
| 98:47 | That's just somebody else's acronym for Right day. You you may well |
|
| 98:53 | seeing something beyond the watch. Probably . So yeah. 1000 for |
|
| 99:17 | Yeah. Well, that's why I to talk about this a little more |
|
| 99:20 | , good question. This is a response. So what we are doing |
|
| 99:26 | we are integrating what the response is we move away from the wall and |
|
| 99:32 | we get to an infinite distance, has to be our total response my |
|
| 99:38 | has to respond to right, the as I move away from the borehole |
|
| 99:44 | ultimately whatever the response is, it ultimately has to be the total |
|
| 99:52 | . If you're saying, gee there be correction, but presumably we, |
|
| 99:56 | we have standoff or we have mud or whatever, we've already corrected for |
|
| 99:59 | . Right? If that's what you're . Oh, so I, so |
|
| 100:09 | presumably I can try again. this, this is not an that |
|
| 100:14 | a concept. And so right here be my borehole wall. Ok. |
|
| 100:20 | so g uh we, we have for borehole effects, things like |
|
| 100:25 | So none of my tool response we assuming would occur from the mud |
|
| 100:30 | right? We corrected all of that , right. So we're looking at |
|
| 100:33 | distance from the whole wall and what of the tool response occurs at a |
|
| 100:40 | less than that. So as I infinitely far away, my total tool |
|
| 100:46 | by definition has to have occurred at distance less than that. If I |
|
| 100:51 | deep enough that it would be by , the total tool response. I |
|
| 101:02 | believe you say that that cleared it . And so we are looking at |
|
| 101:10 | rock, we are looking at what how much, what percentage of my |
|
| 101:15 | . So what I would like would this to basically have a well defined |
|
| 101:19 | of investigation. And so you can these activity tools better than this to |
|
| 101:25 | have no response at a certain distance from the wall and then start accumulating |
|
| 101:31 | , right? For my deeper looking , then you can see where most |
|
| 101:36 | the response right is occurring at a away from the boreal wall kind of |
|
| 101:41 | this region. This is where this picking up the most quickly. |
|
| 101:46 | that, that the idea here is much like a a your cumulative |
|
| 101:52 | density, right? And so what of my grains have a grain size |
|
| 101:58 | than this value? So as we through grain sizes, ultimately, we |
|
| 102:04 | to pick up all the grades. so those grain size, right, |
|
| 102:08 | cumulative distributions were integrating and we have get the total integral under the |
|
| 102:14 | We have to get the total area the curve. By definition. My |
|
| 102:20 | , it will be looking very, have much sensitivity near the borehole |
|
| 102:29 | it picks up, I get a ways away, it doesn't have any |
|
| 102:35 | either. And so you get this of here, right? It's not |
|
| 102:40 | the, the response isn't picking up quickly, then we get a quickly |
|
| 102:46 | response as a tool. That distance in here with this tool right around |
|
| 102:52 | inches is where most of my response occurring from. And then ultimately, |
|
| 102:56 | get far up away from the it's not sensitive to the formation there |
|
| 103:02 | . So this is why my total response by definition as to the one |
|
| 103:09 | looking at a, basically an in under a response for or how it's |
|
| 103:16 | to the rock, a certain distance from the wall give up. But |
|
| 103:24 | look, we'll, we'll look at at this again for resistivity tools and |
|
| 103:28 | that don't know. So I'll try if it's still not clear. Ask |
|
| 103:32 | again and I'll sit and draw Yeah. So here beyond this |
|
| 103:43 | we've reached one. And so it's responding to rock any deeper than that |
|
| 103:47 | all. And this one's not in one's deeper, right? So this |
|
| 103:51 | does get a summer response to a up to about 12 inches and really |
|
| 103:56 | see anything beyond 12 inches. Similarly , this isn't seeing anything beyond about |
|
| 104:03 | inches, doesn't see anything and it see this slope is fairly low. |
|
| 104:11 | it's not very sensitive to what happens the first inch or so, which |
|
| 104:15 | what you want. You don't want reading mud tape, right? You |
|
| 104:19 | wouldn't want this thing picking up and this because then my total response, |
|
| 104:24 | total response would be suppose, suppose thing went up like that. My |
|
| 104:29 | response would be within an inch of parole wall. That, that |
|
| 104:34 | absolutely. Because you're only gonna be mud cake. Ok. We can |
|
| 104:43 | again. We're gonna do this again we get to Relativity tools. So |
|
| 104:47 | , we'll take another look there. again, the depth of investigation for |
|
| 104:53 | about four inches and for the uh a neutron log, right? It's |
|
| 105:02 | like 10. And so the CNL the deep deepest uh depth of |
|
| 105:10 | about 90% comes within 10 inches and this to death. Now, and |
|
| 105:17 | depth of investigation decreases at higher we all understand why opposite the density |
|
| 105:25 | , it's responding to the fluids, more fluids it has the shorter the |
|
| 105:30 | away from the borehole wall will be it thermals captures occur. So OBV |
|
| 105:38 | here, right, I'm getting, example, this one, I'm getting |
|
| 105:41 | captures, right? And for the the what this means is that G |
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| 105:45 | been thermal by this depth. And the density G all my scattering |
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| 105:51 | rate has been captured by this The tool is can't respond to anything |
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| 105:57 | that. That's one way to think it, right? And this is |
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| 106:02 | reverse, like I've said multiple times happens with density blocks, right? |
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| 106:07 | resolution. And I haven't heard about one increasing dramatically. And this one |
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| 106:13 | I find somewhat interesting you were at porosity, you get about one pu |
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| 106:20 | statistics at 3% about three porosity units higher porosity. Why would that be |
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| 106:28 | have more fluid? We're more we have more to measure. Why |
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| 106:32 | I get a higher porosity percent at porosity than well opposite to death. |
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| 106:41 | now we back we did talk about random fluctuation. And what happens is |
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| 106:51 | statistics goes up like the square root event. So your statistical fluctuations get |
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| 106:57 | but your percentage change gets smaller as you accumulate more data, |
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| 107:03 | This is standard random statistics. Hopefully into the square root of a number |
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| 107:11 | measurements before day. Your width of like if you're calculating mean, the |
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| 107:18 | of the means will go down with square root of the number of |
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| 107:21 | Now that says we average over random . Okey doke CNL is rarely used |
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| 107:36 | itself. I talked about this already and clay effects. What was the |
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| 107:41 | effect? Again, the neutron log to read two I because of the |
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| 107:51 | groups associated with the alumin? Yeah, it's often and almost always |
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| 107:58 | in combination with the density locked. is that true? They have opposite |
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| 108:06 | . So they're very sensitive to for example, right? You get |
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| 108:10 | classic thumbs up thing, right? the crossover. Yeah. And then |
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| 108:15 | run with a gamma ray log just gamma rays are almost free, |
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| 108:19 | So why wouldn't you run? That's passive tool. So if you're gonna |
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| 108:24 | , you're gonna run that and it's with these other logs, right? |
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| 108:28 | then you always have to get a , you have to select the |
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| 108:33 | If you're gonna calculate, you're gonna a ferocity this one you're kind of |
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| 108:39 | with that can't measure just display against , if you're gonna measure a capture |
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| 108:45 | cross section, that's not gonna be to anybody, right? You choose |
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| 108:50 | matrix to plot it much. All . So we will run the gamma |
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| 108:55 | two along with the neutron and the . And almost always now it's a |
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| 109:01 | of density, a little extra I guess. And we always have |
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| 109:07 | detectors to go with this. They compensated to us. So here's an |
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| 109:12 | of running it again. So we the gamma ray here as usual high |
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| 109:17 | ray here, low gamma ray there zoned and squared a log, they |
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| 109:22 | that quite well. First thing you it or you have different gamma, |
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| 109:31 | response here. Right. Yes, what that's gonna show. How's my |
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| 109:36 | condition, by the way, this straight line is the bit size and |
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| 109:44 | is my actual, my caliper It gives me the four hole diameter |
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| 109:49 | the average of that. So gee looking for kind of washouts or whatever |
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| 109:55 | where my uh these two deviate from other priorities. That, so what's |
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| 110:02 | here? I have a compensated neutron I have a compensated formation density. |
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| 110:09 | are plotting these based on a limestone . When are they going to |
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| 110:16 | And it's a limestone vote will be in the limestone. Right. |
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| 110:24 | So up here, we have a separation gee we're uh by a large |
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| 110:30 | between the two. what's going on here? We have again, a |
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| 110:36 | separation, dude, right. rather limestone. I'm not sure it |
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| 110:42 | a lot of sense to run this a limestone matrix that you can begin |
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| 110:46 | see as we, as we look these logs and we look at |
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| 110:50 | et cetera. There are cross plots we will have that we actually can |
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| 110:56 | to determine with the all of That's where we're building towards, |
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| 111:00 | So the the cross blocks will help . So environmental corrections uh you, |
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| 111:06 | , you, I really don't think want to get involved in this. |
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| 111:09 | the computer will do this for right? And uh I don't think |
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| 111:14 | gonna prove on their interpretation as this case where I would suggest that's |
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| 111:19 | But you can see all kinds of affected the kind of the bore hole |
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| 111:24 | , uh shoulder bed, right? thickness, lots of stuff like |
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| 111:30 | What's the gas effect? Here's a at the top. It has less |
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| 111:36 | . So it's less dense than So the answer is right below |
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| 111:41 | We already answered this question, These gasses decreased porosity, right? |
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| 111:47 | are assuming that the amount of fluid hydrogen density is the ferocity. I |
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| 111:52 | have enough hydrogen. I haven't filled four space for that. So my |
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| 111:57 | will read too low opposite of the . This is why gas, |
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| 112:04 | Basically, it's not replaced by So, yeah, that, that |
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| 112:10 | don't need to worry about this Uh This excavation effect has largely been |
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| 112:17 | so you can account for this. good luck, you have all of |
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| 112:24 | large mythology effects, et cetera. you should use the density to detect |
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| 112:31 | because it's so much more sensitive. have opposite effects density, right? |
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| 112:38 | here's an example, right? An of this. So again, we |
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| 112:43 | on a limestone matrix. So when agree, what might you conclude? |
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| 112:51 | , it's limestone greening up here, down there, right? A good |
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| 112:57 | that it's limestone. And then what here if we know that if this |
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| 113:02 | a limestone matrix, what's gonna happen my porosity in it? For the |
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| 113:09 | the neutron log, it's gonna read low, increasing porosity is going this |
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| 113:17 | , right? And so we're reading to the density log, what are |
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| 113:23 | reading? This is reading too presumably this is reading too high. |
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| 113:28 | gee we're probably gonna interpret that. guess is gas. OK. So |
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| 113:35 | sensitive huge gas factor, right? . What's happening there? My |
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| 113:49 | right. I've got a, I've a problem with the wash out |
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| 113:58 | And down there, I have a . So shales are gonna, |
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| 114:04 | they they neutron log CNL is gonna affected by the glaze. So the |
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| 114:16 | which I mentioned already, right, accelerator porosity zone right. Again, |
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| 114:21 | can actually have detectors, we have thermal source. And the good news |
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| 114:26 | , right, is that good news that uh we can grind this thing |
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| 114:33 | as the main reason to do uh say for H SME drink. |
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| 114:41 | let's look at now combining the density log uh along with the lipid |
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| 114:52 | right. So porosity we can be from mainly from the pe curve, |
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| 114:58 | , gonna give us the li it's independent of gas and a gas and |
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| 115:06 | liquid can be determined, right? let's take a look at it, |
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| 115:11 | ? Ferocity li cross block. And is gonna be the key to the |
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| 115:15 | we're gonna do. We're going to you gros li crosslots. So these |
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| 115:21 | show you the impact lih maybe you a density log, the density ferocity |
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| 115:27 | one axis, the neutron ferocity on axis. And then you would go |
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| 115:32 | and uh from that, you could an idea at least combinations of what |
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| 115:37 | lithograph might be. Would you in cross plot to get lithograph, which |
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| 115:42 | you use the sidewalk neutron porosity or CNO use the CNL because it is |
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| 115:50 | mythology dependent. So if I want get lithograph, this is an advantage |
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| 115:55 | the tool, not a disadvantage. . So in two D you can |
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| 116:02 | do this, this is an example this, right? So we have |
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| 116:06 | density here and then we can we , we can give it density |
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| 116:11 | But again, it's based on a matrix, right? Why it's a |
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| 116:14 | straight 1 to 1 line? And get the right answer along that |
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| 116:21 | You can see again, uh how of a ferocity effect you're gonna get |
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| 116:27 | versus limestone versus sandstone. Right? there's just various ways of how do |
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| 116:34 | interpret things on this plot, Number of things we should look at |
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| 116:38 | gonna need for the exercise salt, way off these curved, right? |
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| 116:43 | easy to find and hydris pretty far . So I I can do a |
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| 116:48 | good job at identifying these guys. density versus a compensated neutron line, |
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| 116:54 | ? So suppose I read a neutron here based on limestone, gonna get |
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| 117:01 | like a few percent porosity, et and these are just how big the |
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| 117:08 | are in different directions. So the I want to give you, |
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| 117:13 | first example, right. Density talking that, right? Uh based on |
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| 117:20 | limestone matrix, see an al velocity there. So suppose I have a |
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| 117:25 | to that plots here. We're gonna this again if you want, what |
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| 117:30 | be only gonna allow you three no gas and then it has to |
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| 117:35 | a sandstone limestone for a dole What can we say about this? |
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| 117:43 | data plots here. It has to a sandstone. There is no way |
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| 117:52 | average in a limestone versus dolomite right. Uh I have to move |
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| 117:58 | way. Right. The only way get here is with the pure |
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| 118:01 | Yeah. How do I determine the ? Pretty easy. I read it |
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| 118:05 | the chart. Right. Ok. little bit more complicated. What the |
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| 118:10 | here? Not more complicated. the plots here. What must mythology |
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| 118:17 | has to be dolemite? Exactly at extreme way to average in this |
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| 118:23 | Right? OK. Micro obviously in case, 15%. Yeah. Now |
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| 118:31 | little tougher, what's this has to a limestone? Could be a mixture |
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| 118:46 | sandstone and dolemite a little bit uh typical, right? Just together dr |
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| 118:55 | and could, right? Could be dot Sandstone, right? Where we |
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| 119:01 | dolomite cements, that would be a way to move in what's my |
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| 119:07 | So it could be a limestone or could be a sandstone with dolemite cements |
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| 119:13 | it could be a sandstone with calite . That would be a long way |
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| 119:22 | put it. How do I get ? So this is what we're gonna |
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| 119:25 | with all the logs. So we're now, I assume it's a mixture |
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| 119:30 | a sandstone and a dolemite. So you do is draw lines between equal |
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| 119:36 | values 19% 19% 20 to 2021 to to 1. We're like halfway in |
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| 119:44 | . So this would be something like rather than 20% right? It is |
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| 119:53 | we did on the uh that when looked at them lit the density |
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| 120:00 | So always, if you were mixing two other ones, you always draw |
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| 120:04 | between opposite ones about up here. might that mean? I pay attention |
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| 120:17 | ? He highlighted that arrow now. there is a gas effect. So |
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| 120:25 | happens? What happens to my, my density porosity when I had |
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| 120:33 | So I'm here and I actually my is down here. So I have |
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| 120:37 | correct in this direction. If I in this direction, what am I |
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| 120:41 | to my porosity to my density porosity reducing it? So I read too |
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| 120:49 | because I had gas. So I'm it. What am I doing to |
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| 120:53 | neutron ferocity? I'm increasing it. read too low a neutron velocity because |
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| 121:01 | had gas, right? So simply you want to interpret this, I |
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| 121:07 | can't unambiguously interpret this depending on how I'm willing to move it, |
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| 121:13 | They drawing arrows. It could be like a 30% porosity, right? |
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| 121:19 | it was a sandstone, I'm willing move even further. I might have |
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| 121:25 | like a closely saying 30% ferocity Uh Would I extend this to the |
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| 121:32 | line? Probably not because I really get enough gas in it to move |
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| 121:37 | to that far to line. Rule thumb, right? Would have to |
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| 121:41 | too high for us. What's physically out here. It could be a |
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| 121:51 | of other minerals, some sort of or something like that. Right. |
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| 121:56 | . Guess how about here this what could it be? I can |
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| 122:07 | this and this and get here. can mix this. Could I mix |
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| 122:13 | and limestone and get here? I can mix sandstone and dolemite. |
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| 122:20 | there. Right. So it could those two combinations. And again, |
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| 122:25 | like we interpolated before you just draw line, the lines and it |
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| 122:31 | that's gonna be that right. And you would look at how close it |
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| 122:35 | , right? So if, if had a mixture of limestone and |
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| 122:39 | probably something like like 60% limestone. I had a mixture of sandstone and |
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| 122:46 | , right, then it would be more like maybe 30% 30%. |
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| 122:56 | you will be doing that just So dual ferocity compensated neutron log. |
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| 123:02 | , I talked about it like this that I go the wrong way. |
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| 123:05 | talked about that before we have multiple , we put all of this on |
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| 123:09 | same tool. Yeah, that was silver bullet. We still have an |
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| 123:15 | tool you can see, right? uh we are by corrections, |
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| 123:21 | I have to make corrections here. have a spine and ribs plot similar |
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| 123:25 | what we had before for similar And so we're doing kind of the |
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| 123:29 | thing, right. Exactly the same . So um play effect, I |
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| 123:38 | we're talking about here. Right. this zone a we're talking about as |
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| 123:44 | increased crossover due to the decreased absorption the neutron lock of clays. |
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| 123:59 | 7 30 I don't know. Um not gonna get all the way through |
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| 124:03 | . Uh It depends which one I . You wanna try to get through |
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| 124:05 | log before lunch or after lunch? care. You don't care. |
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| 124:14 | it works for me to take a . Now. Uh, so let's |
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| 124:18 | ahead and do that. We'll talk acoustic logs and then we'll do the |
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| 124:22 | after that'll turn out about. Right. As well as we can |
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| 124:28 | questions about anything else if you Ok. Doesn't feel like a Saturday |
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| 5999:59 | |
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