Natural fracture systems in the Woodford Shale, Arbuckle Mountains, Oklahoma

Scope and Method of Study. The focus of this study is the characterization of natural fracture systems in the Devonian/Lower Mississippian Woodford shale in the southern Oklahoma to understand nature of fracturing better. Geologic controls (such as; structural position, mechanical stratigraphy and petrography) that are affected on fractures and fracture behaviors under controlled stress by doing experiments are examined.;Findings and Conclusions. A decrease in average fracture density between organic rich shale and cherty/silica rich shale has been systematically observed. There is a systematic decrease in fracture density moving from cherty and silica rich shale to organic rich shale. Minimum values are observed on organic rich beds and fractures often terminate within the organic rich beds. The general systematic fracture developments on seven outcrops are directly related to local structures and regional stresses.