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  5. NTG (Tied to core and NMR)

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- [Sarita] Now I will go to the net-to gross, where I'm showing how the net-to-gross has been evaluated. Now as I had mentioned to you earlier that the porosity and the net-to-gross, they inversely proportional to each other. So when I calculate the porosity, I have to see if the net-to-gross is changing as well and how much. To do that, I did a sand count calculation from core. The red curve here shows a sand count calculation and the black curve here shows the net-to-gross from Thomas-Steiber. And you can see, there is a reasonable match between the net-to-gross from Thomas-Steiber and net-to-gross from core. So the core has been very crucial here to calibrate our end points. This is what gives me confidence that the end points are robust. I also use another technique to strengthen my computation of net-to-gross and that is NMR. In NMR, you can use NMR, and I had NMR log as well as I had NMR on the core which helped me to have a better calibration of the NMR from the log. I used it to derive net-to-gross and you can refer to my paper to see the process that has gone into it to calculate the NTG from NMR. Here on the right track, you can see that there is a reasonable match between the NMR derived net-to-gross and the net-to-gross derived from sand count, from the Thomas Steiber. Now, the good thing about having an NMR is that you get a continuous net-to-gross. When you have net-to-gross from core, what you do is, you can only do the match where the core is present. What about the rest of places where the core is not present? We can use NMR as a very good tool, calculate our net-to-gross and then calibrate it to the NMR from core so that you can develop confidence in your net-to-gross from Thomas Steiber. I have shown here similarly for another well here but you can see that there is not a very good match. There were also issues in the NMR in this well where we had to look at the tension curve and shift the NMR log accordingly. So it is very crucial to not only look at the NMR log but also look at the tension curve that comes along with it. Because we have a lot of pulses and pulse on this the tool and that's why the DFT shift was very crucial.