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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: Expression of Seeps and Seep-Related
Features on High-Resolution Seismic and
Other Imaging Systems
By
Most high-resolution geophysical
survey systems were
developed by the petroleum industry and by the military as
remote-sensing techniques for measuring seafloor morphologic
and shallow geologic conditions in the marine
environment. These systems have evolved over the past 20
years and now provide a wide range of capabilities and
potential applications. However, they are primarily being
used to provide detailed geologic information for offshore
drilling-hazards surveys and production facility-siting
studies.
High-resolution geophysical
data will augment geochemical
exploration programs when they are used to
target locations with the highest potential for sampling
success. In addition, they will fill the "gap in resolution"
between conventional seismic data and surface geochemical
data. The collection of high resolution
geophysical
data is
completely field-compatible with geochemical exploration
programs and very beneficial to overall program success.
Several examples of anomalous acoustic responses on high-resolution marine seismic profiles are presented here. Many of these anomalies correlate the presence of gaseous hydrocarbons in the shallow sediments and in the water column. It is also very common to falsely associate some "anomalies" with the presence of gas. A complete understanding of the geological environment is critical to proper interpretation.
Simultaneous operation of up to five different high-resolution systems is now possible. This process allows some qualification of the subtle variations in each system's response to shallow acoustic anomalies. It also confirms their relative capacity to resolve various geologic features.
When data are properly collected and interpreted, high-resolution systems can be used to delineate relatively small concentrations of gas and zones of gassy sediments in the shallow geologic section. These systems can also be used to locate and identify surface features such as seep mounds, gas craters, carbonate build-ups, water-column anomalies, and seafloor fractures. All of these features, associated with hydrocarbon migration to the seafloor, provide ideal targets for successful geochemical exploration programs.
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