Further drilling is planned to evaluate an apparent carbon dioxide and helium discovery in East Central Arizona.
A group led by Ridgeway Arizona Oil Corp., a subsidiary of Ridgeway Petroleum Corp., Calgary, will attempt to complete the apparent discovery from eight intervals between 1,450 ft and 1,710 ft in Permian Supai. The well is the Ridgeway/Canstar 1 Plateau Cattle Co., 15-12n-29e, Apache County (OGJ, July 4, p. 66).
Site is 50 miles southeast of inactive Pinta Dome and Navajo Springs helium fields. Helium at about $50/Mcf is a prize, and carbon dioxide at about $1/Mcf could also be quite valuable.
The Plateau Cattle Co. structure, which covers 20,000 acres, appears large enough for possible connection to supply CO2 enhanced oil recovery projects in the Permian basin and perhaps elsewhere, the operating group said.
Production would require about 220 miles of pipeline to connect near Bernalillo, N.M., with an existing C02 pipeline running from McElmo Dome field in Southwest Colorado to EOR projects in West Texas.
INDICATED DISCOVERY
The Ridgeway group drillstem tested Supai intervals at 1,410-79 ft and 1,680-1,720 ft in 1 Plateau Cattle Co.
The shallower dolomite zone, with 31% porosity based on logs, flowed 243 Mcfd of gas with 39 psi drawdown. The zone was slugging filtrate water from a sa based potassium chloride mud designed to keep from dissolving salts in upper Supai during drilling.
The lower zone, which had an estimated 16% porosity in dolomites, flowed about 162 Mcfd of gas.
Logs indicate that 180 ft of the 210 ft of dolomites in the well contain gas. The group expects a calculated absolute open flow of 3-4 MMcfd.
The gas is 90% C02, 0.5-0.8% helium, and 6% nitrogen.
Reservoir quality is termed excellent in every zone, including beach sand in Permian Glorieta (Coconino). Small components of ethane and methane indicate oil might be present in a deeper formation. Surface soil gas contained hydrocarbons up to C5 (pentane) that the group believes came from oil, said John Somers, a Denver engineer working with the group.
DELINEATION PLANS
Total depth of the apparent discovery well is 2,431 ft. Casing has been cemented for production tests.
Pennsylvanian was absent. Drilling progressed from Permian Abo into granite wash, then granite.
The well is on the St. Johns anticline, a 20,000 acre surface structure with 400 ft of surface structural closure on the southeast edge of the Holbrook basin.
The operator plans to follow up with a 4 mile south step-out in 3-11n-29e, near the structure's crest.
It also plans to drill a twin to the apparent discovery well to test a sandstone interval at 200-210 ft with 22-26% porosity that appears to contain gas. This zone, Triassic Chinle or Moenkopi, was too shallow to test in the first well.
The group wants to drill in 22-12n-28e on the Cedar Mesa anticline to determine whether Pennsylvanian zones may be present and whether pentane in soil samples may be coming from an oil source that is structurally lower than the initial test.
Several years ago a 1,676 ft Tenneco Oil Co. well in 22-11n-28e found oil shows in three Permian objectives, and a 3,296 ft Combined Drilling Ventures well in 28-12n-28e had oil shows in Coconino, Supai, and Pennsylvanian.
Lack of rigs in the busy Four Corners area may delay further drilling. Most nearby rigs have only a 2,000 ft depth capacity, and New Mexico weight limits on highways drive up the cost of moving in a large rig from the San Juan basin to $50,000.
The group also has leased the 6,700 acre Coyote Creek anticline southeast of the St. Johns anticline, bringing its holdings in the area to 36,700 acres. Working interests are Ridgeway and Canstar Ventures Corp., Calgary, 40% each, Frank L. Shogrin, Denver, 15%, Cobb Resources, West Columbia, Tex., 3%, and Keith Allen, Calgary, 2%.
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