Development of Microbial Reef Reservoirs at Little Cedar Creek Field, Conecuh County, Alabama
Ganaganath Koralegadara. Department of Geology, Wichita State University, 1845 Fairmount Ave., Box 27, Wichita, KS 67260 [email protected]
Little Cedar Creek field in Conecuh County, Alabama, provides an opportunity to examine microbial development in a shallow, tidal-flat setting without the apparent influence of a rockground substrate. Little Cedar Creek field is the largest Smackover field discovered in the northern U.S. Gulf Coast in the last three decades. It is now the most productive field in the state of Alabama with yearly production of 10.5 million barrels. Little Cedar Creek field sits atop a Smackover gas-driven reservoir located at approximately 11,500 and 11,880 feet. The field demonstrates an oil column of at least 850 feet and extends along strike over at least 8 miles. The bulk of the production has been produced in the last four years.
Previous studies of microbial reef reservoirs in the eastern Gulf Coast (e.g. Appleton and Vocation fields in Alabama) have indicated that development of microbial (thrombolite) reefs is associated with Paleozoic basement highs. In contrast, microbial buildups at Little Cedar Creek are associated with shallow subtidal lithologies without the apparent influence of a rockground substrate.
This study develops a conceptual model of Smackover microbial-reef development at Little Cedar Creek field from core, well logs, and thin sections. In addition, the project examines the influence of microbial fabric and associated nearshore lithologies on the variability of reservoir quality. The results from this study are compared to previous models of microbial development at Appleton field, Escambia County, Alabama, and Vocation field, Monroe County, Alabama. This new information about Jurassic microbial-reef development will create possible new strategies for exploration for other Jurassic carbonates in the Gulf of Mexico and throughout the world.
AAPG Search and Discover Article #90067©2007 AAPG Mid-Continent Section Meeting, Wichita, Kansas