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  3. Sweet Spots Case Study

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- [Voiceover] Now we're looking at Bakken and Three Forks sweet spots, and we see that according to the literature, basement structure really doesn't have any. And we need to have a really nice detailed basement structure map that has magnetic data in order to really get a good sense of what the clay area is, and how to identify sweet spots. We also look at different ways that drill wells are being drilled. So if you're evaluating clay and a package, it's really important to understand that it's not just a matter of the IPs or cumulative production. It's also a matter of understanding your operator and what that operator has been doing, how they approached their drilling. Switch over to Eagle Ford. Eagle Ford in recent trends in 2015, they've really focused on getting costs down as well. And helping the economics by reducing cost. That's all good. Not enough, really, to be able to identify sweet spots and target the preferentially enriched areas. And what we need to do is essentially create a list of the petrophysical, geophysical, and geological information that we need to integrate. So you need image logs, TOC, reservoir thickness, inversion and acoustic impedance to get the net thickness prediction of high porosity. Seismic attributes are good. But above all, history matching. Let's switch over to Marcellus. What do we know about the Marcellus? We now understand the reasons for these different regimes. Why are some areas immature, not productive, why they overmature, and what are the so-called lines of debt in oil, wet gas and dry gas? Not only do we need to know the structure and the thickeness, the shale gross thickness. We need to also know the natural fractures and how they increase to the east. And we also need to understand pore sizes and high concentration of organics to understand where you might have high organic porosity. So let's just focus on Marcellus sweet spot factors. Again, it's all about integrating information that we have, starting with basic history, structure and modeling. And then going with the structural history, depositional history. And then moving further and saying thermal maturity patterns. And then we end with structural things like fracture patterns. Then we can look at the issues of the geochemistry, morphology, etc. So it's really a matter of qualitatively putting together the elements, the aspects, the attributes for each well. So here's a quick look at sweet spot factors in Utica. Again, we need to integrate petrophysical and geophysical analysis. What's different about Utica? Well, Utica has a lot of different purposes. What are some of the additional information points? Paleotopography is important, because we need to know unconformities. Because there could be possibly developed along the unconformities of surface. And then, also we need to understand mineralogy, deal with XRD. We can use isotopes and geochemical fingerprinting with great success here. To figure out, okay, what did happen. Where did the oil go, where did the gas go? Are there any indicator isotopes that would give you a sense of the qualitatively better areas? And interestingly enough, in the Utica is an area where people use airborne EM resistivity measurements to find correlative attributes in a kind of predictive analytics or geostatistics. And I'm excited about that because it's just so useful and accurate. It could be pretty helpful, especially if you tie the airborne EM resistivity measurements to other attributes in the wells. So let's look at the Mississippian Lime sweet spot factors here. The Mississippian is not a shale, obviously. But it's very fascinating. It's been looked at as a resource play. And that sort of presupposes that there's going to be some homogeneity in the reservoir, and there is not. Lynn Watney has done a lot of work, talking about why 5% here, in terms of oil, and it's 20% a mile away. And he has a really compelling explanation that the preferential enrichment really happens due to the migration pathways, the ability of the oil to migrate through fracture networks and also to have trapping mechanism that will allow those areas to stay enriched. So I highly recommend looking at Lynn Watney's work. He's at the Kansas Geological Survey. Niobrara sweet spot factors here. This has low porosity, low permeability. Self-sourced, so you're not wondering about migration pathways. But we need to really understand thermal maturation and natural fracturing along basement faults. So in this case, surface lineaments can be a key indicator. And there's been a lot of wrench fault-triggered fracturing and volumetric changes due to salt movement and dissolution. It's really fascinating. And then one thing I like about the Niobrara is the famous Niobrara oil banana, an area that's a sweet spot in the shape of a banana. And it's the shape of the oil zone. Pretty interesting. And again, here, surface lineaments can be helpful. So there are quite a few factors that work in the Niobrara that may or may not work in others. Let's look at Woodford Shale sweet spot factors. A lot of it has to do with the ability to frac the Woodford. Oil seems to be there, since it's such a prolific source. So you can assume that you could find oil and gas. The question is can you get it out? So you need to look at high fracability index, low ductility, heat flow, thermal maturation. The areas of relative lack of faulting versus areas of quite a bit of faulting, what does that mean? Potentially, you would want to avoid migration pathways, thinking that all you get there would be residual oil zones. But maybe that's not really the case. Maybe you do want to get into the migration pathway. The questions are there, the answers are also there, for you to develop your own working hypotheses and to test them. So let's go to Barnett Shale, the, oh, Rosetta Stone, mother load, granddaddy, whatever. The first. Lots of lessons learned in the Barnett Shale. Lots of lessons about what kinds of fluid to use to drill, how to avoid formation damage, how to avoid drilling into the water, what will happen if you drill into a water zone. So it's really interesting, because one can go and look at the Barnett Shale and look at statistics, say oh, oh, we can see trends. Well, can you? This is a good question. A good time to sit back and say these are not apples and apples. These are apples and oranges, often. Due to different operators, operators' techniques, and also due to different times in which they were drilled, and what we knew in, say, 2013, versus what we knew in, say, 2000. So lots of different things. The Barnett Shale is one of those places where it was great when the gas was $12wasn't great. But it also led to the ability to experiment but also the ability to make foolish choices, thinking that price is going to stay up and so getting into prohibitively expensive basins. Let's take a look again. Moving on, let's look at Permian Basin Shales sweet spot factors there. So here we have the same as others. But let's say something else is different. Let's look at the fact that some of the best reserves in shales in the Permian have been found on the margins and not in the basin center. Why? And then also, understand the direction of sediment gravity flows into the basin. That's also very important. Data mining is probably, to me, the most exciting turning point for each person, because it's an empowering tool. If you can do analystics with your information from your wells. And you can develop meaningful patterns that tie to some observations that you've made or hypotheses, given that you need to tell everybody what your underlying hypotheses are, it's so exciting. So we don't have to just look at data history matching but as it ties to, say, isopachs. You can put together a matrix of different elements in each well, different attributes. And then weight due to different areas that are qualitative and quantitative that you think are really critical to identifying sweet spots. So you might say, okay, I'm going to put togther a combination where I see high TOC, and I see perfect vitrinite reflectance. And I also see certain bottom hole temperatures or pressures. And then I also see certain kind of thickness. When then, those are going to pop out in the data. The clustered attributes will indicate to me a sweet spot. But it could be also even something like salinity or temperature. Of course, resistivity and salinity, those are how we can, they're just different. Different log pressure-physical calculations. If you do not have access to things like pores or other elements. So it's super-exciting, super-interesting.