Patent ID: 7566869
Filing Date: 2009-07-28
Classification: G01V

Abstract:
1. A method of evaluating an earth formation having a fluid mixture including oil and water therein, the method comprising: irradiating the earth formation with a pulsed neutron source, the source being disposed in a borehole; measuring radiation resulting from capture of thermal neutrons by nuclei in the earth formation at at least two detectors; determining from the measurements a value of a fluid zone parameter (FZP) indicative of an oil saturation S defining a fluid zone parameter (FZP) as a ratio of capture gamma ray measurements made by one of the at least two detectors to capture gamma ray measurements made by another of the at least two detectors; establishing values of the FZP for at least two different values of S estimating from the determined value of the FZP and the at least two established values of FZP a value of S