Sedimentologic Controls on the Fracture Distribution and Network Development in Mesaverde Group Sandstone Lithofacies, Uinta Basin, Utah

The Mesaverde Group, Uinta Basin, Utah is the source of current significant natural gas production and contains several trillion cubic feet of undiscovered natural gas resources. To evaluate and model the potential connectivity of hydraulically induced fractures to natural fractures in the subsurface, the natural fracture network was examined using scanline sampling, image and well logs, core and microstructural analyses. Regional fracture sets include subvertical fractures with dominant orientations of: north–south (006–015°), NE (045–059°), NNW (326–342°) and a WNW (271–286°). Sedimentologic and diagenetic characteristics of seven sandstone lithofacies control the fracture development and distribution in the group. Key sedimentologic and diagenetic influences on fracture distribution include bed thickness, stratigraphic architecture, the degree of cementation and the type of cement. From these sedimentologic controls on the character of natural fractures, lithofacies can potentially predict fracture distribution within the Mesaverde Group based on environments of deposition. The presence of NW-trending discontinuous sandstone reservoirs deposited in meandering fluvial environments that are highly fractured by a pervasive WNW-striking fracture set helps to explain fairways of prolific natural gas production within the basin