The consistent low porosity and permeability of reservoirs in the Bakken petroleum system, in the Williston Basin, have increased the need for fracture studies. Although situated in an intracratonic setting, the Williston Basin displays evidence of deformation enabling the presence of regional and local fracturing.

In this study, applicable fracture models are utilized to delineate regional and local fracture orientations within the Williston Region. Northwest and northeast regional fracture trends have been determined by integrating results from previous fracture studies, collecting field data at outcrop locations in the Williston Basin Region, and from subsurface three- dimensional (3-D) seismic data in the Williston Basin. A right-lateral wrench fault strain ellipse model is offered to explain these regional trends. Fracture orientations acquired from outcrop sites (Little Rocky Mountains, Big Snowy Mountains, and Beartooth Mountains) also reveal local, structurally controlled, conjugate fracture trends that are parallel or perpendicular to the structural axis. Using curvature analysis on the interpreted 3-D seismic data, local fracture patterns are also observed within the Williston Basin. When regional and local trends are compared, overlap occurs in fracture orientation showing preference to fractures produced from local structures.

Regional and local trends are also incorporated into a mechanical stratigraphy study using field observations of outcropping Bakken age equivalent and lithologically similar strata from the Bighorn Basin. Dense fracturing occurs within the middle Bakken equivalent member of the Cottonwood Canyon Formation. Extensive fractures that are perpendicular to bedding are also observed and cut through the lower bounding Three Forks Formation, Cottonwood Canyon Formation, and overlying Lodgepole Formation.