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Analysis of geophysical well logs obtained in the State 2-14 borehole, Salton Sea geothermal area, California

January 1, 1988

A complete suite of conventional geophysical well logs was obtained in the upper part of a 3220-m-deep borehole drilled into geothermally altered alluvial sediments on the southeastern edge of the Salton Sea. Geophysical logs obtained in the State 2-14 borehole indicate that neutron porosity, gamma-gamma, and deep-induction logs provide useful information on lithologic trends with depth. The natural gamma log contains almost continuous, high-frequency fluctuations that obscure lithologic trends and that may be related to recent radioisotope redistribution and departure from radiometric equilibrium. Acoustic transit time logs give unrealistically low in situ compressional velocities ranging from 1.8 to 3.0 km/s, whereas acoustic waveform logs indicate that sediment compressional velocities range from less than 3.0 km/s shallower than 1000 m in depth to almost 5.0 km/s at depths greater than 2000 m. Analyses indicate that most log values lie between two lithologic end points: an electrically conductive claystone with moderate neutron porosity, but no effective porosity, and an electrically nonconductive, fully cemented siltstone that has small but finite porosity. -from Authors

Publication Year 1988
Title Analysis of geophysical well logs obtained in the State 2-14 borehole, Salton Sea geothermal area, California
Authors Frederick L. Paillet, R. H. Morin
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Geophysical Research
Index ID 70014348
Record Source USGS Publications Warehouse