Abstract: Statistical Summary of Wells Drilled Below 18,000 ft (5,486 m) in West Texas and Anadarko Basin
In West Texas and southeastern New Mexico, 402 wells have been drilled below 18,000 ft (5,486 m). Of this number, 230 (57%) are producing below 18,000 ft, nearly all of them from the Ellenburger, and 81 (20%) are producing above 18,000 ft. Of the total wells, 134 (33%) were wildcats, of which 72 (54%) were successful at any depth.
In the Texas Panhandle and Oklahoma, 141 wells have been drilled below 18,000 ft. Of this number, 41 (29%) are producing below 18,000 ft, most of them from the Hunton, and 44 (31%) are producing above 18,000 ft. Of the total wells, 73 (52%) were wildcats, of which 30 (41%) were successful at any depth.
In the entire United States a total of 39,097 wells was drilled in 1975. Of this number 23,988 (61%) found oil or gas. Of the total wells, 9,214 (24%) were wildcats, of which 2,143 (23%) were discoveries. Comparison of the percentages of success for deep wells versus all wells in the United States indicates that deep-well prospects are evaluated more thoroughly and scientifically than shallower wells.
Crossplots of initial potentials (MCFD) versus depths of completion intervals exhibit no trend or correlation in either region. This suggests that there is no significant change in porosity or permeability with increasing depth in either the Ellenburger or Hunton carbonate rocks.
Data from Petroleum Engineer show that an average 22,000-ft (6,706 m) Pecos County well cost $72.75 per foot ($240.08 per meter) in 1970. The cost increased to $106.80 (47%) in 1975. An average 20,000-ft (6,096 m) Anadarko basin well cost $82.50 per foot ($272.25 per meter) in 1970 and $122.50 per foot ($404.25 per meter) in 1975 for an increase of 48%. By comparison, the average cost for all wells drilled in the United States increased 112% between 1970 and 1975. It is obvious that carefully monitored drilling practices and experience successfully held down inflationary costs of deep wells in both regions.
AAPG Search and Discovery Article #90970©1977 AAPG Southwest Section Meeting, Abilene, Texas