The Devonian Woodford Shale is a prolific, world-class source rock in the Permian Basin. Vast amounts of oil and gas have been generated by the Woodford Shale, effectively sourcing nearly every potential reservoir from early Ordovician through late Permian. Like so many other source rocks on the heels of Barnett Shale success, the Woodford underwent intense scrutiny as a viable unconventional target. By the mid-2000's, operators yielded some marginally economic gas production in the deep Delaware Basin, while only a few uneconomic vertical oil producers existed throughout the Permian Basin.

Fueled by momentum from Bakken results, Whiting Petroleum Corporation set out to delineate the resource potential of the Woodford. Integration of the previous experiences of some co-authors, the gathering and analysis of geochemical data, and a revised subsurface characterization of Woodford stratigraphy, warranted a test at Whiting's existing acreage at Keystone South Field.

Whiting acquired over 300 feet of conventional core in the upper and middle Woodford, along with an advanced log suite in the vertical pilot hole. To avoid potential water blockage and clay swelling, a synthetic oil-based mud was utilized during the drilling of the lateral. The 3,137' horizontal leg consisted of five frac stages using sliding sleeves and an uncemented liner with swell-packers. Reservoir modeling was performed, primarily to understand potential contribution from a complex fracture network observed in core. Ultimately, the test was uneconomic.

Several key learnings were made from the test at Keystone South Field. Present-day maturity of the Woodford, at this location, has resulted in insufficient oil-in-place and a moderately high viscosity product that cannot produce from a normally pressured reservoir. Synthetic oil-based mud is not necessary, nor did it add value or contribute to any success in this application. Lastly, insufficient lateral length and subsequently low number of stages, as well as poor execution of most frac stages, resulted in an insignificant stimulated rock volume and an uneconomic test.