Salt Withdrawal and Depositional Trends at the Pliocene/Miocene Boundary, Central Eugene Island and Ship Shoal Areas, Offshore Louisiana, USA

T. Farley
Chevron Corporation, P.O. Box 69100, Lafayette, Louisiana 70596

Salt welds imaged on seismic time data mark the former extent of salt in the central Eugene Island and Ship Shoal OCS areas, offshore Louisiana. Two counterregional weld systems trend eastward through the area, a steeply inclined system rooting salt stocks and diapirs along the north and a flatter system associated with more tabular salt to the south. Between these two trends is a local, south-oriented weld system that floors a collapsed salt stock. Relict salt remains associated with welds and cores most of the major oil and gas fields in the region.

The history of salt movement in the central Eugene Island and Ship Shoal areas is recorded in the depositional pattern of sedimentary rocks that displaced salt. Isochore maps of intervals in the Lower Pliocene/Upper Miocene sedimentary section show thickening in areas of salt withdrawal and thinning where seafloor topography associated with emergent salt or counterregional faults impeded deposition. An interval of slope facies rock remains mostly untested in the southern part of the area along with the deeper Miocene section. Traps beneath salt or proximal to salt are among the more obvious remaining prospective features and will be tested as better seismic imaging, improved stratigraphic analysis, and newer conceptual models encourage deeper drilling in the area.

AAPG Search and Discovery Article #90080©2005 GCAGS 55th Annual Convention, New Orleans, Louisiana