--> ABSTRACT: Use of High-Resolution Geophysical and Geotechnical Techniques for Artificial Reef Site Selection, West Cameron Planning Area, Offshore Louisiana, by David L. Pope and John B. Wagner; #91036 (2010)

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Use of High-Resolution Geophysical and Geotechnical Techniques for Artificial Reef Site Selection, West Cameron Planning Area, Offshore Louisiana

David L. Pope, John B. Wagner

Before siting oil and gas platforms on the sea floor as artificial reefs offshore Louisiana, potentially hazardous and unstable geologic conditions must be identified and evaluated to assess their possible impacts on platform stability. Geologic and man-made features can be identified and assessed from high-resolution geophysical techniques (3.5-7.0 kHz echograms, single-channel seismic, and side-scan sonar. Such features include faults, diapirs, scarps, channels, gas seeps, irregular sea-floor topography, mass wasting deposits (slumps, slides, and debris flows), pipelines, and other subsea marine equipment. Geotechnical techniques are utilized to determine lithologic and physical properties of the sediments for correlation with the geophysical data. These techniques are sed to develop a series of geologic maps, cross sections, and pipeline and platform-location maps. Construction of echo-character maps from 3.5-kHz data provides an analysis of near-bottom sedimentation processes (turbidity currents and debris flows).

Acoustic seismic reflection characteristics observed include parallel continuous reflectors resulting from pelagic and hemipelagic sedimentation, broken parallel discontinuous reflections related to turbidite deposition, acoustically chaotic reflectors indicative of mass wasting processes, acoustically semitransparent to transparent reflectors related to slumping and small debris flows, and acoustic wipeout zones indicating gas seepage. By employing high-resolution geophysical techniques in conjunction with geotechnical data, a suitable area on the sea floor for platform emplacement may be determined and may provide insight into near-bottom sedimentation processes.

AAPG Search and Discovery Article #91036©1988 GCAGS and SEPM Gulf Coast Section Meeting; New Orleans, Louisiana, 19-21 October 1988.