Growth to continue at Wyoming's Jonah field

Several operators have reported successes in low permeability zones in the Jonah/Pinedale area in the Green River basin of Southwest Wyoming. At least several hundred more wells are to be drilled in the field, in Sublette County, with issuance in late April of a federal record of decision concerning an environmental impact statement. The decision results from nearly 22 months of study. The field was producing about 170 MMcfd of gas from 70 wells as of late April, said Snyder Oil Corp., Fort

May 18, 1998

4 min read

Several operators have reported successes in low permeability zones in the Jonah/Pinedale area in the Green River basin of Southwest Wyoming.

At least several hundred more wells are to be drilled in the field, in Sublette County, with issuance in late April of a federal record of decision concerning an environmental impact statement. The decision results from nearly 22 months of study.

The field was producing about 170 MMcfd of gas from 70 wells as of late April, said Snyder Oil Corp., Fort Worth.

Drilling to expand

Approval of the EIS resulted from nearly 2 years' study and cooperation between the industry, the public, environmental groups, the U.S. Bureau of Land Management, and other federal, state, and local agencies.

The decision lifts a seven month federal moratorium on approval of permits to drill, Snyder said. It allows for planned development of about 380 incremental wells on 80 acre spacing in the 60,000 acre Jonah Field II natural gas project area.

A joint venture of McMurry Oil Co., Casper, Wyo., and MCNIC Oil & Gas Co., Detroit, expects to drill another 200 wells on its acreage, including about 16 this year. The companies have drilled 46 Jonah wells, producing a combined 110 MMcfd of gas, without a dry hole.

Ultra Petroleum Corp., Vancouver, B.C., said it has assigned reserves to only 8,100 acres of its total inventory of more than 350,000 acres in the area as of early April.

Ultra has a well stimulation/completion agreement with Halliburton Energy Services Inc. and gathering and drilling agreements with Western Gas Resources Inc. that relate to various parts of its operations in the area.

Much more exploratory drilling remains, Ultra said. Its geoscientists were analyzing a detailed aeromagnetic survey. The company acquired a regional 2D seismic grid that is being scrutinized as the first step in optimizing 3D seismic surveys that might be scheduled.

Ultra also formed an industry group to acquire four shear wave vertical seismic profiles in its wells. That data would complement existing seismic and well log information.

Recent completions

Large frac jobs have resulted in several recent record initial flow rates for wells in the field.

McMurry and MCNIC gauged the 7-13 Yellow Point, in 13-28n-109w, at a record 16.1 MMcfd of gas on a 32/64 in. choke with 2,550 psi flowing tubing pressure. The Apr. 30 test involved six stimulated and commingled intervals from Cretaceous Wardell through Upper Lance. Condensate volumes and ultimate reserves were to be established. TD is 10,600 ft.

Typical Jonah field wells initially produce 4-7 MMcfd from three or four intervals, MCNIC noted.

The two companies completed the 11-35 Stud Horse Butte, in 35-29n-108w, in March at a record initial rate of 15.1 MMcfd of gas on a 26/64 in. choke at 3,500 psi with 230 b/d of condensate. EUR is 11 bcf. TD is 11,600 ft.

Then the Snyder operated 3-26 Stud Horse Butte, in 26-29n-108w, flowed a sustained 15.2 MMcfd of gas on a 20/64 in. choke at 2,000 psi with 212 b/d of condensate. EUR is 10 bcf, and TD is 11,900 ft.

Ultra, Colt Energy, and Western Gas said the 11-8 Lizard Head exploratory well, in 8-31n-108w, flowed 1.5 MMcfd of gas on a 16/64 in. choke with 1,025 psi FTP from 12,830-962 ft, the deepest completion attempt in the Jonah/Pinedale area through mid-April. This flow rate was measured shortly after a frac job with 220,000 lb of high strength proppant.

The zone contains 80 net ft of pay out of more than 500 ft of overpressured potential in the well bore, Ultra said. As many as five fracs are needed to fully complete the well.