Oil and Gas Entrapment, Louisiana Shelf, Offshore Gulf Coast Region

J. -C. Pratsch

Oil and gas accumulations in the Louisiana offshore are caused by vertical hydrocarbon migration. Source beds for both thermal gas and oil lie considerably deeper than reservoirs. The required vertical pathways are steeply dipping faults and salt structures (ridges and diapirs). Faults and salt structures indicate the continuing presence of rift structures that began along a normal passive continental margin during the Pennsylvanian. Tectonic trends are northeast, northwest, north, and west-east; they follow well-established regional stress systems. Listric and growth faults commonly are too shallow for vertical hydrocarbon migration and require connection with vertical faults. Vertical oil and gas migration is predictable in its directions. The underlying geological, geo hysical, and geochemical processes are understood and are not different from such processes in other productive basins. Secondary salt layers at shallower levels cause interruptions of vertical oil and gas migration; at the same time these interruptions seem to indicate a large future exploration potential on the Louisiana shelf.

AAPG Search and Discovery Article #91029©1989 AAPG GCAGS and GC Section of SEPM Meeting, October 25-27, 1989, Corpus Christi, Texas.