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

Daniel L. Orange, AOA Geophysics Inc. and U.C. Santa Cruz, 7532 Sandholdt Rd, Suite 6, Moss Landing, CA 95039, phone: 831-633-7404, fax: 831-633-2684, dan_orange@aoageophysics.com, Norman Maher, AOA Geophysics Inc, 7532 Sandholdt Rd, Moss Landing, CA 95039, Adam Heffernan, AOA Geophysics Inc, 1300 W. Sam Houston Parkway South, Suite 225, Houston, TX 77042, Dan McConnell, AOA Geophysics Inc, 1300 W. Sam Houston Parkway South, Suite 225, Houston, 77042, Matt Levey, AOA Geophysics Inc, 7532 Sandholdt Rd, Moss Landing, 95039, John Decker, Unocal Indonesia Co, Jakarta, Indonesia, Philip A. Teas, Exploration, Unocal, Pasir Ridge, P.O Box 276, Balikpapan, 76102, Indonesia, Rhys D. Schneider, Unocal Indonesia, Pasir Ridge, Balikpapan, 76102, Indonesia, Arthur H. Saller, Unocal Corp, 14141 Southwest Freeway, Sugar Land, TX 77478, Joseph A. Curiale, Unocal Corporation, 14141 Southwest Freeway, Sugar Land, TX 77478, Elizabeth A.E. Johnson, Unocal Corporation, 14141 Southwest Freeway, Sugar Land, 77478, Dem Demetriou, Project Development International Limited, Parallel House, 32 London Road, Guildford, Surrey, GU1 2AB, England, Du Sik Johng, Noble Energy, 100 Glenborough, Suite 100, Houston, TX 77067, Philippe Jeanjean, BP Corporation, PO Box 3092, 501 Westlake Park Blvd, Houston, TX 77253, James A. Thomson, Geohazards Team, BP, Houston, TX, and Michael M. Angell, William Lettis & Associates, 1777 Botelho Rd. Suite 262, Walnut Creek, CA 94596.

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 targetted 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.

Seismic Geomorphology II
2005 AAPG Annual Convention (June 19-22, 2005) Technical Program