Three-Dimensional Structural Restorations of Allochthonous Salt, Green Canyon and Ewing Bank, Northern Gulf of Mexico: Preliminary Results

Barry C. Mcbride, Mark G. Rowan, Paul Weimer

Neogene strata of offshore Louisiana are a major exploration play. Future exploration successes will be enhanced by a better understanding of the integrated evolution of salt flow, reservoir deposition and hydrocarbon migration. Because of the inherent three-dimensional structural complexity of salt flow and its control on sediment deposition and deformation, the standard technique of restoration in two-dimensions does not always accurately portray the evolution due to out-of-plane movement. Therefore, three-dimensional structural restorations have been undertaken to resolve more accurately the structural and stratigraphic evolution.

Three-dimensional seismic data have been interpreted and integrated with wells and biostratigraphy over an area of approximately 1000 sq. miles in central Ewing Bank and north-central Green Canyon lease areas. The interpretation was loaded into the new structural restoration software GEOSEC 3-D to conduct sequential restorations of the region back to 5 Ma. The restoration procedure utilized a modified form of Rowan's (1993) restoration method for salt and integrates decompaction, isostatic subsidence, and the determination of sea-floor paleotopography.

The restorations highlight the three-dimensional aspect of both salt and sediment deformation and provide a significant improvement in understanding the three-dimensional geometries and kinematics. The three-dimensional analysis is critical in assessing how sedimentation influences salt flow and, in turn, how salt flow influences facies development ant the geometry of the sediment transport system through time. The resolution of the structural and stratigraphic evolution in three-dimensions (four-dimensional analysis) provides the framework for modeling dynamic hydrocarbon migration pathways and evaluating both sub-salt and supra-salt hydrocarbon potential.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995