--> Abstract: Identifying Processes Relevant to Exploration and Geohazards with High-Resolution Seafloor Mapping, by Daniel L. Orange, Norman Maher, Adam Heffernan Dan McConnell, Matt Levey, John Decker, Philip A. Teas, Rhys D. Schneider, Arthur H. Saller, Joseph A. Curiale, Elizabeth A. E. Johnson, Dem Demetriou, Du Sik Johng, Philippe Jeanjean, James A. Thomson, and Michael M. Angell; #90039 (2005)

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Identifying Processes Relevant to Exploration and Geohazards with High-Resolution Seafloor Mapping

Daniel L. Orange1, Norman Maher2, Adam Heffernan3, Dan McConnell3, Matt Levey2, John Decker4, Philip A. Teas5, Rhys D. Schneider5, Arthur H. Saller6, Joseph A. Curiale6, Elizabeth A.E. Johnson6, Dem Demetriou7, Du Sik Johng8, Philippe Jeanjean9, James A. Thomson9, and Michael M. Angell10
1 AOA Geophysics Inc. and U.C. Santa Cruz, Moss Landing, CA
2 AOA Geophysics Inc, Moss Landing, CA
3 AOA Geophysics Inc, Houston, TX
4 Unocal Indonesia Co, Jakarta, Indonesia
5 Unocal Indonesia, Balikpapan, Indonesia
6 Unocal Corporation, Sugar Land, TX
7 Project Development International Limited, Guildford, Surrey, England
8 Noble Energy, Houston, TX
9 BP Corporation, Houston, TX
10 William Lettis & Associates, Walnut Creek,

Advances in hydrographic surveying allow rapid acquisition of high-resolution seafloor data relevant to exploration and geohazards. Hydrographic data are significantly less expensive to acquire than 3D seismic and can be processed at sea within 12-24 hours of acquisition; hydrographic data, however, do not provide information on the section below the seafloor, and are not a replacement for 3D seismic. Hydrographic data can be acquired simultaneously with high-resolution sub-bottom profiler data, gravity and magnetics. 2D seismic data can also be collected simultaneously if a slower survey speed and longer line turns are acceptable.

Seafloor seeps related to the hydrocarbon system affect both the shape and acoustic character of the seafloor. By integrating high-resolution seafloor bathymetry and backscatter with synthetic aperture radar, gravity and magnetics, and especially 2D seismic, seafloor seeps that are potentially active, and that can be tied to the hydrocarbon system, can be targeted for follow-on sampling via navigated cores. In addition to seafloor seeps, high-resolution seafloor maps can provide new insight into classic questions of deep marine sedimentation including basin floor fans, and deep sea sediment waves.

Rapid surveying for geohazards with hull-mounted or AUV systems permits acquisition of large areas, which allows more robust interpretation than if data are only acquired along a narrow corridor. Seafloor data are integrated with high-resolution sub-bottom profiler data, exploration and high-resolution seismic, cores and geotechnical boreholes to evaluate processes active in a field area as well as their levels of activity. Examples include a gas field offshore Ecuador with an exposed plunging anticline at the seafloor; a complex region of slope failure, gas expulsion, folding and faulting offshore Trinidad; and the toe of the Sigsbee Escarpment in the Gulf of Mexico characterized by salt tectonics, slumping and overpressure.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005