ABSTRACT

Porous dolomites in the Hunton Group contain the most prolific gas reservoirs, on a per-well or per-acre basis, in the Anadarko basin of western Oklahoma. Aledo field, in Dewey County, will ultimately yield ~92 Bcfg (billion cubic feet of gas) in each square mile of Hunton reservoir, making it the most prolific field in the basin. The Phillips No. 1 Callie "B" well, located in the Aledo field, has cumulatively produced ~77 Bcfg from Hunton dolomite perforations, making it the largest gas well in the basin. Across the State line, in Hemphill County, Texas, the Gulf No. 1 Helton well was completed for 2.75 Bcfgd initial potential, calculated absolute open flow (IP CAOF), from Hunton dolomite perforations, making it the largest initial potential test in the basin.

A Hunton dolomite porosity fairway is present as a northeast-trending band across the Anadarko basin; it extends from the Hunton's truncational limit in Garfield County, Oklahoma, southwestward to the basin's southern fault limit in Wheeler County, Texas. This fairway roughly encompasses any Hunton Group reservoir, regardless of formation, where the principal lithology is dolomite. It is estimated that >80% of Hunton oil and gas production within this fairway comes from the uppermost 100 ft of Hunton, regardless of the specific formation that is present in the subcrop at its truncated top.

The Hunton dolomite porosity fairway, when superimposed on regional maps of either the Hunton structure of thickness, shows only a slight association. The closest association, however, is with a regional isopach map of the Woodford Shale, which unconformably overlies the Hunton. This emphasizes the importance that diagenesis, rather than subcrop formation or primary deposition, has on the presence of reservoir-porosity development.