This article is based on
Chapter 8 of "The Log Analysis Handbook" by E. R. Crain, P.Eng., published by Pennwell Books 1986 Updated 2004.
webpage version is the copyrighted intellectual
property of the author.
Do not copy or distribute in any form without explicit
In order of preference, use the following methods:
1. Archie method for clean sands and clean carbonates.
Simandoux method for shaly sands.
Porosity saturation product method if RW@FT is unknown or cannot
be estimated from SP, R0 or Rwa methods.
Bulk volume water (dual water) method instead of Simandoux if
it is desirable to match modern computer truck results.
Waxman-Smits method if good Qv and CEC data are available.
Resistivity ratio method as a last resort in open holes.
Thermal decay time (TDT) data in cases hole production monitoring
situations, or where no open hole logs were run.
Water saturation for complex lithology example from various
other water saturation formula are, or have been, in use. Some
are listed below and even more can be found in the literature.
The ultimate universal formula has not yet been found. The most useful methods and their solutions are shown elsewhere
in this Handbook. Some additional equations are shown in the table
below, but you will have to solve for SW yourself.
Summary of Water Saturation Methods