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Borehole-wall imaging with acoustic and optical televiewers for fractured-bedrock aquifer investigations

John H. Williams
U. S. Geological Survey
425 Jordan Road
Troy, New York, 12180

Carole D. Johnson
U. S. Geological Survey
11 Sherman Place
Storrs, Connecticut, 06269

Abstract

Imaging with acoustic and optical televiewers results in continuous and oriented 360 degree views of the borehole wall from which the character and orientation of lithologic and structural features can be defined for fractured-bedrock aquifer investigations. Fractures are more clearly defined under a wider range of conditions on acoustic images than on optical images including dark-colored rocks, cloudy borehole water, and coated borehole walls. However, optical images allow for the direct viewing of the character of and relation between lithology, fractures, foliation, and bedding. The most powerful approach is the combined application of acoustic and optical imaging with integrated interpretation. Borehole-wall imaging provides information useful for the collection and interpretation of flowmeter and other geophysical logs, core samples, and hydraulic and water-quality data from packer testing and monitoring.

Final copy as submitted to Seventh International Symposium on Borehole Geophysics for Minerals, Geotechnical, and Groundwater Applications for publication as: Williams, J.H., and Johnson, C.D., 2000, Borehole-wall imaging with acoustic and optical televiewers for fractured-bedrock aquifer investigations, in Seventh International Symposium on Borehole Geophysics for Minerals, Geotechnical, and Groundwater Applications, October 24-24, 2000, Proceedings: Minerals and Geotechnical Logging Society, Houston, p.43-53.

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