DETERMINING A FLUID FRACTION IN AN EARTH FORMATION

摘要

A method of determining the fraction of a fluid selected from at least two fluids contained in an earth formation is provided. The method comprises inducing a magnetic field in a region of said earth formation, conducting a pulse-echo NMR measurement in said region of the earth formation, and selecting a relationship between the NMR echo response from said fluids, the fractions of the fluids, and a variable which affects the NMR echo response in a manner dependent on the fractions of said fluids. By varying said variable in the course of the NMR measurement the measured NMR echo response is affected in a manner dependent on the fractions of said fluids. The fraction of the selected fluid is then determined by fitting the NMR echo response to said selected relationship.