Oil Field Inductive Resistivity Logging in Steel-Cased Wells

40145 Electromagnetic Instruments, Inc. Large quantities of oil remain in existing domestic oil fields, but much remains isolated or has been bypassed. A major problem in older oil fields is that it is impossible to obtain meaningful measurements of the present state of the reservoir through the steel well casings. This project will develop an electromagnetic borehole logging tool for geophysical measurements inside a cased well. Numerical modeling will be performed and field tests conducted to demonstrate the feasibility of inductive resistivity logging through steel-cased on a reservoir scale. The proposed numerical work will determine the limits and resolution of logging through casing, and set design criteria for a new generation of borehole logging tools. In addition the field tests will determine noise and measurement obstacles and test the various schemes proposed to remove the effect of casing. Anticipated Results/Potential Commercial Applications as described by the awardee: The low frequency electromagnetic borehole logging system should provide a simple, reliable and economical means of measuring formation resistivity trough steel-cased wells, thus providing an independent in situ measurement of saturation, pore fluid, and permeability of a reservoir. In the domestic United States there are several thousand oil fields, some having more than 6,000 wells; hence, logging cased holes could represent a large service industry demand.