The primary geological zone for drilling in the Woodford Interests is the Woodford Shale. The shale is mostly Late Devonian in age, although some is reported as being Earliest Carboniferous. The formation was deposited as part of a global Late Devonian marine transgression. It is an important source rock in the area for both oil and gas in the south-central basins of the USA, and the shale is considered an important oil and particularly gas reservoir.
Production from shale is reported as far back as 1934. The advent of improved horizontal drilling and hydraulic fracture techniques has increased the prospectivity of the shale to become a significant unconventional target for oil and gas. Publications have suggested that total gas-in-place for the Woodford Shale play is 830 Tcf, and oil-in place in the order of 250 Bbbls. However, these numbers are based on a number of assumptions covering a very large area. In May 2011 there were 173 drilling rigs active in the Anadarko and Arkoma Basins, all drilling horizontal wells.
In only four years of active drilling, the Woodford formation now contains 1,281 producing wells. Most of the wells are where the Woodford Shale is in the dry gas window, greater than 50 ft thick and at a relatively shallow depth (<12,000 ft). The Woodford Oil window play in Hughes and Coal Counties Oklahoma is experiencing increasing activity, with the most active companies being Continental Resources and Newfield.
Because the Woodford oil play is relatively new, there is little long term production data to establish statistical ultimate recovery projections for the trend. However, Newfield has reported that they have completed six wells and five of those wells had initial production of over 1,400 boepd. The 30 day production average on those wells was 950 boepd and the 90 day average was 760 boepd. While these are based on a limited sample of completions in the Woodford and may not reflect the averages, they indicate the attractiveness of the play. The early production figures provided by Newfield are comparable to the initial rates in the Bakken play and the well costs are on average less.