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The Black Warrior basin of northwestern Alabama is an excellent locality to prospect for combination petroleum traps; to date over 1,000 wells have been drilled in the region and 62 petroleum fields and pools have been discovered. Mississippian sandstone reservoirs presently have the greatest hydrocarbon potential, the Carter and Lewis sandstones being the most economic of these reservoirs. Cumulative production for the Carter includes more than 700,000 bbl of oil and 12 bcf of gas. The Lewis has produced over 5,000 bbl of oil and 12 bcf of gas. The Carter was deposited as part of a high-constructive, elongate to lobate delta which prograded from northwest to southeast into the basin. The Lewis accumulated as a series of elongate, northwest to southeast-trending sand bodi s on a shallow marine shelf. Carter distributary
mouth bar and distal bar lithofacies and Lewis marine central bar lithofacies constitute the primary Mississippian reservoirs in the basin. Primary interparticulate porosity has been reduced through the development of quartz overgrowths and/or calcite cementation. Secondary porosity involves leaching of carbonate allochems, calcite cement, and/or matrix. The Carter prodelta and interdistributary bay shales and Lewis marine shales make excellent petroleum source rocks. These shales contain amorphous and herbaceous kerogen. The state of alteration of the kerogen indicates that the thermal history of the basin has been favorable for the generation and preservation of hydrocarbons, principally gas. The petroleum-trapping capabilities of these strata have been enhanced because of their ass ciation with normal faults.
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