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Application of advanced geophysical logging methods in the characterization of a fractured-sedimentary bedrock aquifer, Ventura County, California

Water-Resources Investigations Report 2000-4083
Prepared in cooperation with the University of Waterloo, Canada
By: , , , and 
https://doi.org/10.3133/wri004083

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Abstract

An integrated suite of advanced geophysical logging methods was used to characterize the geology and hydrology of three boreholes completed in fractured-sedimentary bedrock in Ventura County, California. The geophysical methods included caliper, gamma, electromagnetic induction, borehole deviation, optical and acoustic televiewer, borehole radar, fluid resistivity, temperature, and electromagnetic flowmeter. The geophysical logging 1) provided insights useful for the overall geohydrologic characterization of the bedrock and 2) enhanced the value of information collected by other methods from the boreholes including core-sample analysis, multiple-level monitoring, and packer testing.

The logged boreholes, which have open intervals of 100 to 200 feet, penetrate a sequence of interbedded sandstone and mudstone with bedding striking 220 to 250 degrees and dipping 15 to 40 degrees to the northwest. Fractures intersected by the boreholes include fractures parallel to bedding and fractures with variable strike that dip moderately to steeply. Two to three flow zones were detected in each borehole. The flow zones consist of bedding-parallel or steeply dipping fractures or a combination of bedding-parallel fractures and moderately to steeply dipping fractures. About 75 to more than 90 percent of the measured flow under pumped conditions was produced by only one of the flow zones in each borehole.

Suggested Citation

Williams, J.H., Lane, J.W., Jr., Singha, Kamini, and Haeni, F.P., 2002, Application of advanced geophysical logging methods in the characterization of a fractured-sedimentary bedrock aquifer, Ventura County, California: U.S. Geological Survey Water-Resources Investigations Report 2000–4083, 28 p., https://pubs.er.usgs.gov/publication/wri004083.

Study Area

Table of Contents

  • Introduction
  • Geophysical Logging Methods
  • Geophysical Log Anaysis
  • Summary
  • References
Publication type Report
Publication Subtype USGS Numbered Series
Title Application of advanced geophysical logging methods in the characterization of a fractured-sedimentary bedrock aquifer, Ventura County, California
Series title Water-Resources Investigations Report
Series number 2000-4083
DOI 10.3133/wri004083
Year Published 2002
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Office of Ground Water
Description 28 p.
Country United States
State California
County Ventura County
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