PETTY, ANDREW J., Minerals Management Service, New Orleans, Louisiana

Abstract: Petroleum Exploration and Stratigraphy of the Lower Cretaceous James Limestone (Aptian) and Andrew Formation (Albian): Main Pass, Viosca Knoll, and Mobile Areas, Northeastern Gulf of Mexico

Hydrocarbon exploration of Lower Cretaceous carbonates on the Outer Continental Shelf began in 1968, with the Andrew Formation and James Limestone as targets. Six fields were declared in this carbonate trend: the Andrew Formation's Main Pass 253 and Main Pass 221 relinquished Fields; the James Limestone's Viosca Knoll 252, Viosca Knoll 256 (terminated), Viosca Knoll 69, and Mobile 991 Fields. Additional James shows are observed in Viosca Knoll lease Block 114 and Viosca Knoll lease Block 117, which initially discovered James Limestone gas during drilling to a deeper target. Lower Cretaceous hydrocarbon potential occurs on relatively unexplored regions: the Southern Platform in the Desoto Canyon/Florida Middle Ground areas, Tampa Basin, Sarasota Arch, and in the South Florida Basin adjacent to the Lower Cretaceous shelf-edge-reef-trend.

Stratigraphically between the Dantzler and Paluxy formations, the Andrew Formation is composed of an upper Washita and two Fredericksburg aged carbonate platforms separated by shelf mudstones. The James Limestone, comprising upper and lower members, dominate thin shale members of the Pearsall Formation. Six facies compose the Lower Cretaceous carbonates where grainstone detritus zones, adjacent to reef/patch reef boundstones, were redistributed by wave action over the interior platform. Shelf mudstones, nearest the paleoshoreline, occur in the central and eastern portions of the Mobile and northern Viosca Knoll Areas. Shelf-edge-reef boundstones interfinger with oolitic grainstones on the shelf and fore reef mudstones off the shelf. 

AAPG Search and Discovery Article #90924©1999 GCAGS Annual Meeting Lafayette, Louisiana