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Greater Green River Basin Production Improvement Project Beverly Blakeney DeJarnett (; 817-737-2435) BBD Consulting Fort Worth, Texas Frank H. Lim (; 817-877-7889) Union Pacific Resources Group P. O. Box 7 Fort Worth, Texas 76101 D. Calogero (; 817-498-9892) Engineering Consultant Fort Worth, Texas 1. Introduction The Greater Green River Basin (GGRB) of Wyoming has produced abundant oil and gas out of multiple reservoirs for over 60 years, and large quantities of gas remain untapped in tight gas sandstone reservoirs. Even though GGRB production has been established in formations from the Paleozoic to the Tertiary, recent activity has focused on several Cretaceous reservoirs. Two of these formations, the Almond and the Frontier Formations, have been classified as tight sands (permeabilities <0.1 millidarcy) and are prolific gas producers in the GGRB. The formations are typically naturally fractured and have been exploited using conventional vertical well technology. In most cases, hydraulic fracture treatments must be performed when completing these wells to increase gas production rates to economic levels. However, hydraulic fracture treatments may not be the most effective method for improving gas production from these tight reservoirs. With the maturation of horizontal drilling technology it has become apparent that horizontal drilling may be particularly well suited to reservoirs where hydraulic fracturing is inefficient either because hydraulic fractures are parallel to natural fracture strike and/or because encasing shales are poor stress barriers to limit excessive hydraulic fracture height growth.