ECHOLS, JOHN, and DONALD GODDARD, Lousiana State University, Basin Research Institute, Baton Rouge, LA

ABSTRACT: Lower Wilcox Reservoir Characteristics: Evidence for Bypassed and Subjacent Hydrocarbon Potential, East Central Louisiana

The Wilcox Basin is a large oil productive area in east central Louisiana and adjoining southwest Mississippi. The basin is estimated to contain over one billion barrels of remaining oil in place distributed within unstructured deltaic reservoirs. The Basin isfilled with about 3,600 feet of deltaic sediments of the Wilcox Group, which is subdivided, conventionally, into upper, middle, and lower intervals. Wilcox production has totalled about one billion barrels of oil since the initial discovery in the early 1940's. In east central Louisiana the upper and middle Wilcox have produced most of the oil (70%) with southwest Mississippi producing the balance. The lower Wilcox, with the exception of a 100-150 foot interval at its top, has produced only a minute amount of this total.

A detailed study of a 500 foot, 3 1/2 inch diameter conventional core together with a suite of state-of-the-art high resolution well logs were taken in the Bee Brake Field of East Central Louisiana. A combination of this data with a re-examination of existing oil productive trends within the middle Wilcox and at the top of the lower Wilcox has been employed in predicting the existence of new areas with stratigraphic trapping potential in the lower Wilcox.

Petrophysical evaluation of this well bore, combined with sedimentological studies and detailed structural and net sand mapping has provided reliable evidence for the existence of bypassed oil in subaqueous levee facies associated with distributary mouth bars. Additional lower Wilcox sediments, interpreted as distal bar sands contain minor oil shows.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.