SHALE GAS POTENTIAL OF THE FLOYD SHALE IN THE BLACK WARRIOR BASIN

The commercial success of Barnett Shale production in the Fort Worth basin has drawn abundant attention to unconventional shale gas formations. An unconventional shale gas play is considered a fully self-contained petroleum system, whereby critical petroleum system elements, source, reservoir, and seal coincide in the same formation. The Mississippian Floyd Shale in Northwestern Alabama represents a potential unconventional shale gas resource in the Black Warrior basin; and is the focus of this study. This gray to black fossiliferous shale is relatively thick (500ft; ~150 m), and bounded above and below by dense limestone units comparable to those necessary to contain induced fractures required to achieve Barnett Shale production. Although the Floyd has been previously identified as the possible source rock for conventional Mississippian oil production in the Black Warrior basin, investigation of its unconventional thermogenic gas potential has not been undertaken. Because of their importance to the understanding of the reservoir, the quantity, quality, distribution, and thermal maturity of organic matter within the Floyd Shale were investigated for comparison with similar data on the Barnett Shale. The most important factors for commercial gas production (geochemical characteristics, thermal maturity and physical properties) are expected to be analogous to the Barnett. Through analyzing digital data of one hundred well logs in four counties (Marion, Lamar, Fayette and Pickens), a log-derived indicator of shale thermal maturity will be established and correlated with measurement and production datasets. Lithological trends from core and well logs will provide insight into depositional environments. Mineralogy and petrography will focus on identification of clay-types and abundances using SEM and XRD. Rock-Eval pyrolysis will resolve the stratigraphic variation in organic matter. Using equations developed from gas desorption data, well logs, and geochemical measurements, organic content (TOC) and gas in place (GIP) of the Floyd Shale will be precisely mapped. This study, apart from delineating prime gas potential targets in the Black Warrior basin, will also provide a simplified scheme for analyzing other unconventional shale formations along the Ouachita Front, and other geologic provinces.