Abstract: The Tallahala Creek Complex, Smith County, Mississippi: The Crest Is Not Always the Best

Edwin E. Sticker

The Tallahala Creek complex, comprising both Tallahala Creek and East Tallahala Creek fields, is a salt-induced anticline transected by two down-to-the-north fault systems. Since 1967, the upper portion of the Jurassic Smackover Formation has yielded almost 15 million bbl of oil and 20 billion ft³ of gas, or 75% and 64% of the total oil and gas, respectively, produced from the fields. Contemporaneous sediment accumulation and structural growth have created various lithofacies in the upper Smackover, thereby significantly affecting reservoir heterogeneity. These lithofacies can be delineated by their structural position on the anticline. On the most downdip and downthrown portions of the structure, the upper Smackover consists of a series of gray, fine- to medium-grained san stones separated by limestones. These sandstones generally exhibit both high porosity and permeability, and have thus contributed over 95% of the total Smackover production. Updip the upper Smackover becomes increasingly calcareous, finally grading into a sandy, occasionally dolomitic, limestone on the crest and southern upthrown flank of the anticline. This limestone lithofacies has been noncommercial as a reservoir rock, as evidenced by the less than 7000 bbl of oil cumulatively produced from the Smackover in two of the structurally highest wells, the Shell 2 E. M. Lane and the Shell 1 F. James. Structural and stratigraphic relationships discovered through field development of the Tallahala Creek complex have significantly altered the conventional idea that "the crest is always the bes ."

AAPG Search and Discovery Article #90983©1994 GCAGS and Gulf Coast SEPM 44th Annual Meeting, Austin, Texas, October 6-7, 1994