The interpretation of seismic, gravity, and well data in two areas of southwest Louisiana suggest that lateral salt flow has influenced each area's structural evolution, depositional patterns, and hydrocarbon migration.

The Gillis-English Bayou-West Manchester area of eastern Calcasieu Parish is underlain by an extensive salt sheet of over thirty square miles at depths of 14,000' to 20,000'. Loading and extension shaped the salt sheet resulting in two salt highs or at West Manchester and Gillis-English Bayou Fields. Associated with this salt movement is a significant erosional event underlying West Manchester Field where over 1,200' of Vicksburg section is absent. The faulting associated with the salt withdrawal provide hydrocarbon pathways and shallower traps.

Swiss Lake Field, in northern Cameron Parish, overlies a large allochthonous salt mass that was once part of a large ancestral salt ridge extending from Hackberry to Big Lake Fields. Nine wells which encountered the top of the salt and several seismic lines help to define a detached salt feature underlying over twenty square miles at depths from 8,500' to 18,000'. Salt withdrawal in the Hackberry-Big Lake area influenced the depositional patterns of the Oligocene lower Hackberry channel systems and contributed to the expansion of the Marginulina- Miogypsinoides section near Sweet Lake.

High quality 2-D and 3-D seismic data will continue to enhance the regional understanding of salt movement in the onshore Gulf Coast. Additional examples of lateral salt flow will be recognized, and some may prove to have subsalt hydrocarbon potential.

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