Pinedale Field: Geophysical Applications in a Major Tight Gas Field, Green River Basin, Wyoming, U.S.A

Sally G. Zinke, Ultra Petroleum Corp, 304 Inverness Way, Suite 295, Englewood, CO 80112, phone: 303-645-9837, [email protected] and Sarah E. Shearer, Ultra Petroleum Corporation, Englewood, CO.

The Pinedale Field, one of the largest gas fields in the Greater Green River Basin of southwest Wyoming, is being developed along with Jonah Field, as a significant over-pressured, tight-gas sandstone reservoir in the Upper Cretaceous Lance Pool. The Pinedale Anticline has a 5000 foot thick gross hydrocarbon bearing section comprised of fluvial and flood-plain facies rocks deposited in a broad alluvial valley nearly coincident with the anticline structure. Since the acquisition of the initial 3D seismic survey in the Mesa area in late 1999, Ultra has used 3D seismic data to guide drilling location selection, define drilling hazards, and extend Lance Pool production laterally and vertically on the anticline. Specialized seismic processing has facilitated ability to identify stratigraphic sweet spots in the field, over-pressure, and handle azimuthal anisotropy. Efforts to better understand the inter-well geometry of sand bodies and the behavior of the massive hydraulic frac'ing techniques used to enhance production has lead to the use of cross well tomography and micro-seismic frac monitoring to map the orientation and fabric between wells. The interpretation and understanding from these applications has enhanced the reservoir model and validated much of the geological and geophysical understanding of the Pinedale Field.