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Develop the equation for the Pickett plot in clean formations of the petrophysics lecture.
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Develop the equation for the Pickett plot in shaly formations composed by laminar shales shown on slide 23 of the petrophysics lecture. Refer to the ONEPETRO paper discussed in class "Extensions of Pickett Plots for the Analysis of shaly formations by well logs" SPWLA-1990-v31n5a3.
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This is an example using data of the Morrow sandstone, Sorrento field of Southeastern Colorado presented in SPE 81196-PA. You can download this paper from ONEPETRO free of charge. The well logs are shown in Figure 3 of that paper. The plots you are going to build are somewhat similar to those in Figures 4, 5 and 6.
a. Draw lines of constant water saturation equal to 100%, 50%, 25% (assume n =2).
b. What is the value of m?
c. What is the value of the product a.Rw?
d. Draw lines of constant process speed (k/PHI) equal to 20000,2000, 200, 20.
e. Draw standard crossplots of capillary pressure vs. water saturation for k/ =2000, 200, 20 (md over fraction porosity). This is similar to Figure 6 in SPE 81196-PA. Add your calculation of capillary pressure at 100% water saturation. Ignore the line going down from 90 to 100% water saturation in Figure 6.
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This is an example using data of the Lower Cretaceous Glauconite Formation, West-central Alberta. Use Python to solve this problem. Data are presented in the D2L excel file. Calculate for each depth:
a. Compressional velocity (Vc)
b. Shear transit time (DELTAt shear)
c. Shear velocity (Vs)
d. Dynamic Poisson's ratio (PR)
e. Dynamic Shear modulus (G)
f. Dynamic Young's Modulus ( E )
g. Brittleness index
h. Vertical Biot's constant (DELTA v = 0.6+[ma*PHIeffec]).
i. Prepare plots of GR curve vs. depth and the items you have calculated in questions 2 (Vshale), 4 (effective porosity), 10 (water saturation).
