Geology and Development of Mills Ranch Complex--World's Deepest Field: GEOLOGIC NOTES

Abstract

The Mills Ranch complex is fast developing into one of the largest fields in the deep Anadarko basin. The complex is part of a deep buried granite uplift which extends northwest-southeast along a large thrust fault and is complicated by numerous faults and unconformities. The discovery well of the deep Mills Ranch Hunton play, the Freeport Oil Co. 1 Sidney Fabian, was drilled in 1972 to a depth of 21,640 ft (6,492 m) and completed at a calculated open flow rate of 93,050 Mcf per day. Since that time at least three separate productive reservoirs in the Silurian-Devonian Hunton have been delineated. The Hunton, averaging 930 ft (279 m) in thickness, has production from both the Chimneyhill and Henryhouse sections. Wells in the Hunton on the main structure are capable of pro ucing up to 20,000 Mcf per day. The deepest production in the world was found in the Arbuckle from 24,435 to 26,518 ft (7,330 to 7,955 m) in the Chevron et al 1 Ledbetter, completed in October 1977. Significant deep production on the Mills Ranch complex will cause increased deep-drilling activity in fields now producing only from the Hunton as well as on nonproducing structures in this part of the Anadarko basin.