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Gee Whiz Geophysics…But What
About the Log 
Data
?
By
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2Goolsby Brothers and Associates, Inc, 8174 South Holly Street, #507, Centennial, CO 80122 ([email protected])
Abstract
Geologists and geophysicists have been trying to
squeeze as much usable information as possible from seismic data since before
the discovery of bright spots. Today they display this information with 3D
visualization software, and 3D seismic is touted as the answer to all things….but
what about the log data?
Most log data (even older log data) has 10-25 times
better vertical resolution thanseismic data. However, many geologists and
geophysicists today treat log data much like it was treated in 1935. They obtain
copies of the logs, display them in cross sections, correlate them, and map
them. Mixed-vintage, incomplete, and/or poor quality log data, however, can lead
to serious problems in interpretation. Without accurate, normalized,
high-resolution log data for every well in a study area, geological correlations
and maps may be incorrect. As a result, 3D seismic interpretations based on this
data may turn out to be amazingly colorful but inaccurate representations of
what is actually happening in the subsurface.
Today the oil and gas industry is challenged with
evaluating declining production in aging fields, in many cases involving
hundreds of wells with log data recorded from 1935 to last week. New plays often
involve laminated, poor-quality, low permeability, fractured, or unconventional
reservoirs. Using resistivity and SP inversion processing and neural network
modeling run on their PC, geologists and geophysicists can generate complete
suites of accurate, high-resolution, edited, log, core, and production data
for
every well in a study area. Examples from the Mid-Continent, California, and
Rocky Mountains are shown.
Using resistivity and SP inversion modeling and neural networks together.