Exploration Applications of PSDM Data in Deep Water West Africa

Steven G. Henry¹, Al Danforth², Sujata Venkatraman³, Peter Nuttall³, and Bernard Lachaux^3
1Innovative Exploration Services, Las Cruces, NM
²Consultant, Houston, TX. (3) ION, Houston, TX

Pre-stacked Depth Migrated (PSDM) seismic data has successfully imaged reflectors beneath salt structures in the post salt and in the pre-salt of West Africa. PSDM data is providing a significant exploration advantage in areas with lateral velocity variations (water bottom, shale, salt, volcanics, basement). The use of regional (400 km dip - 2000 km strike), deep (25 km) PSDM data for understanding basic geology (plate tectonics, basin formation, lithologies) and for developing new plays (petroleum systems, DHI’s) is relatively new. Significant advantages of using PSDM data include; 1) imaging beneath salt, 2) improved reflector geometric relationships, and 3) depth and thickness estimates. In this poster we present new ideas on how PSDM data can be used to examine important exploration problems that were much more difficult and in some cases impossible to solve using time data.

Over 26,000 km of regional PSDM data have been interpreted in Angola, Congo and Gabon, with many new regional features mapped along these continental margins. Using this depth data, relationships between the underlying pre-salt basin geometry and the overlying styles of salt tectonics have been interpreted, along with a map of the original depositional thickness of the salt. The methods (depth seismic stratigraphy, paleo-sea level flattening, cratonic isostacy) used in making these interpretations, will be illustrated. These new applications of PSDM data for exploration are important first steps, as future exploration will likely see PSDM data becoming the interpretation standard, replacing current methods of seismic interpretation that utilize two-way time sections.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas