Deposition, Facies Patterns, and Hydrocarbon Potential of Bangor Limestone (Mississippian), Northern Black Warrior Basin, Alabama and Mississippi: ABSTRACT

Abstract

Abstract The Bangor Limestone was deposited as a carbonate shelf, ramp and basin sequence on the northeast flank of the Warrior Basin. Progradation to the southwest was episodic and resulted in several cyclic units which grade upward from deeper water muddy facies into grainy shoal facies. Shoal facies regression eventually expanded the shelf more than 14 miles basinward. The Bangor can be divided into three members which are mappable throughout the shelf and ramp. Each member contains a shelf-blanketing, grain-support facies rich in crinoids, bryozoans and oolites. Widely scattered patches of porous reservoir-quality lime occur in this shallow water suite; however, there are no indications of broad porosity pockets which might serve as large stratigraphic traps on the shelf. Known gas accumulations on the Bangor shelf, i.e., Whitehouse and Nauvoo Fields, appear to be low-relief closures having small reserves. Future discoveries are anticipated to be analogous to these. Small potential reserves and probable inability to seismically detect the low-relief structures make the shelf an unattractive objective. The Bangor ramp may offer better hydrocarbon potential. One speculative ramp model is presented which suggests the possibility of bryozoancrinoidal mounding. Suggested mound-trap closure could reach 100 to 150 feet. If such mounds were densely spaced or areally large, hydrocarbon reserves could be attractive.