--> ABSTRACT: Recent Developments at Wilburton Field, Latimer County, Oklahoma, by Richard C. Hook; #91003 (1990).

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ABSTRACT: Recent Developments at Wilburton Field, Latimer County, Oklahoma

Richard C. Hook

Recent deeper drilling in Wilburton field has resulted in new production from the Spiro, Cromwell, and Arbuckle formations. The new field reservoirs occur on a large horst block that underlies the old field pay in the overthrust Spiro. ARCO Oil and Gas first discovered this production in Sec. 36, T5N, R17E from the in-situ Spiro, beneath a low-angle thrust fault. Nine wells now produce from this Spiro reservoir.

Structural data generated by drilling the in-situ Spiro reservoir revealed a southwest-dipping, upthrown fault block with nearly 2000 ft of vertical relief. ARCO Oil and Gas tested this feature to basement with their 2 Yourman well in Sec. 15, T5N, 18E, discovering prolific gas production from the Arbuckle. The Arbuckle porosity consists largely of vugs, solution channels, and open fractures in a clean dolostone. The trap is created by the fault juxtaposition of the Arbuckle reservoir against impermeable Mississippian and Pennsylvanian shales along the updip (north) edge of the field. Conventional neutron-density logs show low porosity, but cores and Formation Microscanner images reveal the vugs, some of which are several inches across. Permeability is created by the solution channels and a pervasive system of open fractures and microfaults. All current production is from the uppermost 700 ft of the Arbuckle, with a gas column of at least 1100 ft. To date, ten Arbuckle wells have been completed, one is in completion, and one is drilling. Exploration is currently focused along the southern edge of the Arkoma basin, in a similar structural setting to Wilburton field.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990