Extending Borehole Electromagnetic Imaging to Cased Wells

The borehole electromagnetic (EM) system was upgraded to have enough S/N ratio to measure fields between two steel-cased boreholes.

Laboratory studies and numerical analyses show that casing effects can be separated from geologic information if casing properties are known. Casing properties can be accurately estimated using the proposed new borehole logging device

Project Synopsis

Borehole EM measurements are of proven utility in monitoring certain reservoir production processes (i.e., steam flooding and water flooding). Metal casing causes large EM attenuation and phase shifts, but recent laboratory measurements have indicated that seeing through ordinary metal casing should be possible in lower frequency ranges. In this project we have extended the simple laboratory models to more realistic cases, improved instrumentation and demonstrated field capabilities. Result of this project will greatly broaden the utility of EM imaging by allowing much more work in mature reservoirs.

The first two figures indicate that a 2m-long casing segment has the same effect to the magnetic field as an infinite casing in a whole space. The third figure shows a conceptual logging tool for measuring necessary EM fields to be used for accurately estimating casing properties.

Participants

Chevron, Mobil, Texaco, EPA, Halliburton, OYO, JNOC, Schlumberger, WALS (currently Baker-Atlas), LBNL, and LLNL.

Related Publications

Song, Y., and K.H. Lee, Electromagnetic fields due to a loop current in a cased borehole surrounded by uniform whole space, Report LBNL-42371, 1998.

Becker, A., B. Wang, K.H. Lee, and M. Wilt, Subsurface electromagnetic measurement through steel casing, Report LBNL-42375, 1998.

Lee, K.H.,H.J. Ki, and Y. Song, Electromagnetic method for analyzing the property of steel casing, Report LBNL-41525, 1998.

Becker, A., B. Wang and K.H. Lee, Subsurface electromagnetic measurement through steel casing, Expanded Abstracts, SEG International Exposition and 67th Annual Meeting, Dallas, Texas, Nov. 2-7, 1997.

Wilt, M., A. Becker, B. Wang, K.H. Lee and B. Spies, Crosshole EM in steel-cased boreholes, Expanded Abstracts, SEG International Exposition and 66th Annual Meeting, Denver, Colo., Nov. 10-15, 1996.

Uchida, T., K.H. Lee and M. Wilt, Effect of steel casing on crosshole EM measurement, Expanded Abstracts, SEG International Exposition and 61st Annual Meeting, Houston, Texas, Nov. 10-14, 1991.

Contact

Kurt Nihei
510-486-5349
ktnihei@lbl.gov
Fax: 510/486-5686

Valeri A. Korneev
(510)486-7214
vakorneev@lbl.gov

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