JAMES, ALAN T., and LLOYD M. WENGER, Exxon Production Research Company, Houston, TX; MICHAEL B. MELIA and ARTHUR H. ROSS, Exxon Exploration Company, Houston, TX; and CARY P. KUMINECZ, Empire Exploration, Buffalo, NY

ABSTRACT: Recognition of a New Hydrocarbon Play in a Mature Exploration Area through Integration of Geochemical, Palynologic, Geologic, and Seismic interpretations (onshore Northern Rim of Gulf of Mexico)

Through the application of detailed geochemical oil correlation, palynostratigraphic and paleontologic source description, and integration within the geologic framework, a new hydrocarbon play has been recognized in an area that has been heavily drilled for fifty years along the northern rim of the Gulf of Mexico Basin. A new Triassic, lacustrine-sourced oil family has been recognized in several Norphlet/Werner and Smackover reservoirs in northeast Texas and northwestern Louisiana. They are most abundant along the Mexia-Talco fault zone in east Texas and along the northern bounding faults of the Gulf rim in Louisiana.

The Triassic lacustrine oils are distinct from other oil families within the area (Jurassic Smackover, Lower Cretaceous, and upper Cretaceous Woodbine/Tuscaloosa families) having a very unusual geochemical character (abundant isoprenoids to C40 and branched methyl components). This has been documented through the use of a new high resolution C4 - C19 analysis and more conventional geochemical approaches. Mixtures of Triassic oils with theother oil families have also been recognized in Smackover and Cretaceous reservoirs along the fault zones.

These oils have been correlated to organic-rich lacustrine shales of the Triassic Eagle Mills Formation. They represent a new hydrocarbon play in a previously poorly known portion of the geologic section.

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