West Bastian Bay Field, South Louisiana: ABSTRACT

Abstract

The large, domal structure at West Bastian Bay field, central Plaquemines Parish, Louisiana, is interpreted as a deep-seated salt dome. A large, east-west striking, south-dipping, contemporaneous normal fault traverses the dome and controls accumulation of oil and gas in multiple upper Miocene sands. At the time of maximum growth along the Bastian Bay fault, sediment was deposited approximately three times as fast in the downthrown block, where most of the hydrocarbon accumulation occurs. The relative thickness of sediments shows that domal uplift, deposition of upper Miocene and younger beds, and movement along Bastian Bay fault were contemporaneous. Reliable electric log correlations together with paleontological data from well samples in the field area, afford excellen data for a detailed study of contemporaneous normal faulting, a type of faulting common to Miocene sediments of the Gulf Coast and important to exploration for oil and gas. Microfaunal and lithologic data from conventional cores through productive intervals show that the R and S sands were deposited predominantly in nonmarine environments. These sands in turn are separated by dense homogenous gray-black shares, deposited in marine environments equivalent to those existing on the modern continental shelf. Production has been established in 20 sands ranging in depth from 8,677 to 15,305 feet. End_of_Article - Last_Page 351------------