Page 67 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2
P. 67
Basic Principles, Definitions, and Data 55
(5-70)
The more general form of Equation 5-70, commonly used, is:
(5-71)
An even more general form recognizes that the constant, a, in Equation 5-49 is
not necessarily unity:
sw = (2) (5-72)
v.
The foregoing equations are close approximations in clean formations having
a regular distribution of porosity. The accuracy of the equations will not be as
good in formations with vugs or fractures.
As shown in Figure 5-37, Patnode and Wyllie [59] found that the presence of
clays affected the relationship between water saturation and resistivity index.
Figure 5-37. Effect of conductive solids on the relationship between
resistivity index and water saturation [59].
