ABSTRACT

Microfractures in sandstone samples were used as surrogates to infer macrofracture characteristics in two Pennsylvanian Pottsville Formation wells, Black Warrior Basin, Alabama. Sidewall cores from one well were oriented using image logs and drilling-and retrieval-related features visible on cores. Microfractures identified using SEM-based cathodoluminescence imaging of horizontal thin sections provided information on fracture orientation, crosscutting relations, intensity, and likelihood of preserved open fractures. Northwest-striking fractures formed before northeast-and east-striking fractures, matching patterns observed in outcrop. Porosity preservation in large fractures is predicted to be extensive except where postkinematic ferroan carbonate cements are prevalent. Gas flares were observed from some depth intervals predicted to have open fractures and moderate to high fracture intensity.