Oil production from Carboniferous reservoirs (fig.1) in the Black Warrior basin of Alabama (fig. 2) reached a peak in 1985 (Masingill, 1991) and has declined in recent years although much additional oil may be producible using improved recovery strategies, such as waterflooding, chemical injection, strategic well placement, and infill drilling. High-quality reservoir characterization and reliable criteria for recognition of the types and scale of reservoir heterogeneity are crucial to development of enhanced recovery strategies, because reservoirs typically contain numerous features at megascopic, macroscopic, mesoscopic, and microscopic levels that affect fluid flow (Weber, 1986; Haldorsen and Damsleth, 1993). Previous investigations concerning the Black Warrior basin have been regional in scope, addressing the large-scale depositional setting of reservoir units (for example, Cleaves and Broussard, 1980; Cleaves, 1983; Thomas, 1988). Bearden and Mancini (1985) and Epsman (1987) established salient features pertinent to hydrocarbon production at the field scale, such as trapping mechanism. Because oil production in the basin is declining, secondary recovery projects have been initiated in several oil fields, and improved recovery utilizing advanced technology is being considered, this report, which documents controls on the occurrence and producibility of oil from heterogeneous Carboniferous reservoirs in the Black Warrior basin, is timely.