Introduction
Oil test wells can provide information on the depth, age, inclination, porosity,
permeability, density, faulting, folding, and organic content of geologic
formations mapped at the surface, or on units not recognized in surface
outcrops. Formation density, as expressed in sonic and density logs commonly
obtained when wells are drilled, has become increasingly important in making a
crustal-scale 3-D seismic velocity model for the San Francisco Bay region. This
model will be used for the calculation of realistic strong-ground motion synthetic
seismograms (Brocher and others, 1997), and to determine the geometry of the
basement surface beneath Tertiary basins (Jachens and others, 1997). The
availability of this density and other information for oil test wells has, until
recently, been restricted for competitive reasons, but several petroleum
companies have recently made these data available. Accordingly, we began in
1992 to obtain these data to help prepare new geologic maps and geophysical
models for the San Francisco Bay region, and to share the information with the
public.
This report contains brief descriptions of information and materials available
for 1,550 oil exploration and production wells in the following counties: Alameda
(42), Butte (31), Colusa (103), Contra Costa (102), Glenn (103), Humboldt (33),
Marin (6), Mendocino (2), Merced (33), Monterey (172), Napa (5), Placer (2),
Sacramento (72), San Benito (51), San Joaquin (164), San Mateo (73), Santa Clara
(8), Santa Cruz (23), Shasta (3), Siskiyou (1), Solano (251), Sonoma (10), Stanislaus
(29), Sutter (59), Tehama (59), and Yolo (113).
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First posted June 11, 2001
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