Berlin gas field in Beckham County, Oklahoma, was discovered in 1977, and is the largest Atoka (Pennsylvanian) hydrocarbon accumulation in the Anadarko basin. It is an overpressured reservoir at a depth of 15,000 ft (4,572 m) and occupies a surface area of 41 mi² (106 km²). The reservoir rock consists of recycled, detrital Arbuckle dolomite (Cambrian-Ordovician), and contains ultimate recoverable reserves of 242 to 362 bcf.

Arbuckle dolomite and limited exposures of Precambrian granite rocks were eroded from the Amarillo-Wichita Mountains in the Atokan and were deposited as a terrigenous, sandy dolomite clastic wedge adjacent to the uplift. In the late Atokan, the Elk City structure was uplifted and subaerially exposed in the vicinity of the northern limit of the dolomite clastic wedge. The detrital dolomite on the structure was concurrently eroded and recycled northward as a shallow marine fan delta. Subsequent recrystallization destroyed the detrital depositional texture and created the present intercrystalline porosity.

The deep Elk City structure consists of an upthrust block bound by the late Atokan unconformity that is genetically associated with the Berlin fan delta. Present relief on the upthrust block and overlying anticlinal folds formed during post-Atokan growth of the structure.

Berlin field provides a model of a large, localized clastic deposit derived from uplift and erosion of a prominent structure, and it is an example of the potential for large detrital stratigraphic traps around the perimeters of prominent structures that contain crestal unconformities.

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