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  3. Building the Petrophysical Model

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- [Gary A. Simpson] So as we talk about building the petrophysical models, we'll go into some background and then talk about the petrophysical analysis challenges we had. So Hess, starting in early or late 2013 through 2014 drilled a series of five science wells across our acreage. On these, we ran full logging suites. We cut 360 foot of whole core on each well. The thing that we found out is that the cornerstone building of the petrophysical models required that we had accurate mineralogy. And so, coupling this with the probabilistic interpretation approach, which was used to solve for the complex mineralogy and fluids. Some of our challenges included that these wells are drilled with oil-based mud, so traditional RXO devices could not be used. So we found that there were unique evaluation challenges that existed for the Three Forks and the Bakken formations, primarily the laminated thin bed reservoir sections, and of course the organic, rich shales with the high TOC. The thing that really surprised us the most was the hyper-salinity formation waters of the Bakken petroleum system. And we found that this impacted our core analysis results, and I'll discuss that later. So as we look at going from these cores and from these, all these logs, to benchmarking those with core, we took our advance logging measurement. And we wanted to be sure that we could pair up as many of these logs as we could to core measurements that we could make to benchmark not only the mineralogy and the porosity in this. And so we used a series of instruments. We used X-ray fluorescence, we used FTIR, we used DRIFTS measurements, we used X-ray diffraction, we did a series of core porosity and water saturation using Dean-Stark. We even made some core NMR measurements. And finally, and actually, this is something we're just, been doing in the last couple of months, is we're doing a series of rock core mechanical properties to compare. From this, we were able to develop a petrophysics model that allowed us to compare to the core data. And from this, we developed our petrophysics models, which included multi-mineral analysis, laminated thin bed analysis, dielectric saturation models, probabilistic fluid and porosity models, NMR models, and rock mechanical properties, where we calculated 3D VTI. Now that we have all these models developed, we're using them to help us develop a basin-wide petrophysics model for use in the whole basin. So to start out our benchmarking, and to understand our mineralogy.