Fractures
Three principal types of fracture systems are present in the Williston Basin. The first is related to regional lineaments which developed in response to regional tectonic stresses and crustal flexure during the Phanerozoic. The second developed locally along drapes over basement structures. The third is related to over pressuring.
In the study area, natural fractures found in core are not abundant, but where present, are best preserved within dolomite beds. Most fractures in limestones were healed by calcite or anhydrite cements. Fractures in dolomites are usually short-segment, tension gashes within the burrow-mottled facies. However, swarms or closely spaced vertical fractures are also present within other dolomitized facies. Most of the fractures within the Red River D zone interval contain solution enhancement.