Ernest A. Mancini1, William C. Parcell2
(1) The University of Alabama, Tuscaloosa, AL
(2) University of Alabama, Tuscaloosa, AL
ABSTRACT: Integrated Carbonate Exploration Approach for Upper Jurassic Smackover Reef and Shoal Reservoirs, Northeastern Gulf of Mexico
The Upper Jurassic Smackover Formation is a major petroleum reservoir in the northeastern Gulf of Mexico. Smackover petroleum traps are principally salt-related structures or basement-related features that are discernible utilizing 3-D seismic data. Therefore, the delineation of a structural anomaly is fundamental to a successful exploration strategy. However, defining a Smackover reservoir associated with these structural features has proven to be difficult using only 3-D seismic profiles. Smackover reservoirs are chiefly upper Smackover peloidal/ooid shoal packstones and grainstones and middle to upper Smackover microbial bindstones and bafflestones that have undergone porosity and permeability enhancement through dissolution and dolomitization. Knowledge of reservoir succession and development is critical to prospecting for Smackover hydrocarbons. The microbial reservoirs are formed under late transgressive to early highstand systems tracts depositional conditions and are generally associated with a hardground or rockground and maximum flooding event. The shoal reservoirs are formed under late highstand systems tract depositional conditions and are generally associated with a reduced rate in sea-level rise and an increased carbonate sediment accumulation rate. Diagenetic processes are greatly influenced by the development of the bounding-unconformity that overlies the latest highstand systems tract deposits, which are typically Buckner anhydrites. Sequence stratigraphic analysis, 3-D geologic modeling, and diagenesis studies are crucial in characterizing Smackover reservoirs. An integrated carbonate exploration approach which utilizes 3-D seismic imaging for petroleum trap identification and delineation and employs sequence stratigraphic analysis, 3-D geologic modeling and diagenetic studies for predicting reservoir quality and extent is the key to successful Smackover petroleum exploration.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado