BARIA, LAWRENCE R., Jura-Search, Jackson, MS; KARL KAUFMANN and BRIAN J. SIMS, Valioso Petroleum Co., Jackson, MS

ABSTRACT: Facies, Seismic and Sequence Stratigraphic Aspects of the Frisco City Sand, Haynesville Formation, Southwest Alabama

The Frisco City (basal Haynesville sand) as well as middle and upper Haynesville sands have received a concerted exploration effort in recent months due to the prolific oil potential they provide at relatively shallow depths. These Haynesville targets are locate throughout Monroe and adjacent counties in southwest Alabama at depths from 9,000 to 12,000 feet (2730- 3650 meters). Completion rates above 3000 BOPD with sustained production between 250 to 1000 BOPD per well have made this currently one ofthe most active plays in the U.S. onshore.

Individual fields occur as discrete four-way structural closures where late Jurassic sands formed around or draped over Paleozoic basement highs (inselbergs). Examination of slabed core indicates that the reservoir sands are composed of gravelly alluvial fans, wadi style braided stream deposits, and to a lesser extent, eolian and playa sediments. Petrographic studies indicate little chemical alteration of feldspars or rock fragments; as a result, porosities and permeabilities in these sands are quite high; commonly averaging 20% and up to several darcies.

This desert style of deposition and diagenesis is further supported by stratigraphic cross-sections drawn from the Conecuh Arch westward and southward into adjacent basins. These sections demonstrate that the Frisco City Sand is facies related to thick deposits of lower Haynesville salt. Such an association would infer Frisco City deposition during a sea-level low stand in an arid setting high on the Conecuh platform.

Seismic, in combination with subsurface control, delineates several Haynesville sequence boundaries as well as assists in the presence/absence recognition of the Frisco City Sand.

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