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The Road Hollow field, discovered in November 1981 in Lincoln County, Wyoming, is the northernmost field on the Absaroka plate producing trend of the Utah-Wyoming Overthrust belt. The discovery well, the Road Hollow Unit 4, gauged an initial potential of 10 MCFGD and 440 BCPD from the Ordovician Bighorn Dolomite. Chemical analysis of the gas indicates greater than 98% hydrocarbon gases with only 0.3% hydrogen sulfide.
The Road Hollow field is an anticlinal culmination formed during emplacement of the Absaroka plate. The structure is well defined by seismic data. In the discovery well, the Ordovician Bighorn Dolomite contains approximately 150 ft (45 m) of greater than 2.5% porosity, whereas dolomite in the Devonian Darby Formation contains about 10 ft (3 m) of greater than 2.5% porosity. Gas was recovered during a drill-stem test of the Darby, but the formation is not presently considered to be economical. Shales and anhydrites within the Darby Formation appear to form the vertical seal for the Bighorn trap. The source of hydrocarbons for the Road Hollow field is believed to be subthrust Cretaceous shales. Geochemical analysis of these shales indicates a good, mature source for oil and gas.
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