Page 222 - Petrophysics 2E

PROBLEMS 195

c. Find arithmetic, geometric, and harmonic means of the
permeability. Also, calculate the standard deviation, normalized
mean, and dispersion of the three means.
d. Determine the arithmetic porosity mean and the median porosity.

8. Considering the porosity and permeability data in Table 3B:
a. Determine the best permeability-porosity correlation.
b. What is the average grain diameter of each sample?
c. Calculate RQI and plot against porosity.
d. Determine the number of flow units and corresponding FZI.
9. The log surveys in a well indicated irreducible water saturation of
18% and an average porosity of 15%. Core analysis as well as well-test
analysis indicated a reservoir rock permeability of 16 mD. Estimate
the bound water irreducible and free fluid index for this formation.
10. Estimate the permeability (mD) of a reservoir rock which has
a porosity of 13% and an irreducible water saturation of 20%.
Assuming this permeability is representative of the flow unit:

a. Calculate the reservoir quality index RQI (pm).
b. Calculate the flow zone indicator FZI.
c. Calculate the Tiab flow unit characterization factor HT.

11. An NMR log was run in a well, indicating a porosity of 13% and log
mean of relaxation time 2.5 ps at the depth of 7,500. Estimate the
permeability at this depth for this well, using SDR correlations.
12. Core analysis in a new well in a formation with similar petrophysical
characteristics to the TAGI formation revealed a horizontal permeab-
ility of 15 mD.

A. Assuming that the formation has equal contents of Kaolinite and
Illite, estimate the vertical permeability and anisotropy ratio for
this well, using the models developed for the TAGI formation, for
the following cases:

a. Only horizontal permeability is known.
b. Only horizontal permeability and porosity data are available
(porosity = 13%).
c. Horizontal permeability, porosity, and average grain diameter
data are available (grain diameter = 0.025 mm).

B. Rework the example, assuming that this formation contains a high
percentage of Illite clay.