Reservoir characterization of microbial reef reservoirs at Little Cedar Creek Field, Conecuh County, Alabama

Abstract

Little Cedar Creek Field (LCCF) in Conecuh County, Alabama 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. The LCCF gives an opportunity to identify the characteristics of microbial (thrombolite) developments in shallow water deposits and differentiate it from the nearby reef reservoirs which grow directly on Paleozoic basement paleohighs. Previous studies from this area have indicated that Jurassic microbial buildups are associated with Paleozoic basement paleohighs. In contrast, microbial buildups at LCCF apparently developed in shallow subtidal environment without the influence of basement rockgrounds. The objective of this project is to examine the microbial reef reservoirs at Little Cedar Creek in order to identify any relationship between depositional fabric type and reservoir quality distribution. Furthermore this study compares these nearshore thrombolite facies to microbial fabric types identified at Appleton and Vocation fields, Alabama and will focus on the types of Jurassic microbial developments in this field and the poor reservoir rock fabric types identified in other fields and characterized as lagoon, and subtidal facies. This study will improve the understanding of Upper Jurassic Smackover microbial development, its lithologic fabrics and controls on reservoir quality. The results will improve the exploration strategy to find other stratigraphic microbial carbonate reservoirs worldwide. Examining the controls on reservoir quality distribution at LCCF will provide new insights into this unique and prolific petroleum reservoir facies