Forget Cows & Tourists, Sublette is "Natural Gas Country"
In 1997, Sublette had the largest volume of natural gas production of any county in Wyoming and Jonah was the largest sweet gas producing field in the state.
by Rob Shaul

Sublette County has always been known for its ranching and tourism, but driven by the huge Jonah natural gas field in the southern part of the county, Sublette is rapidly becoming known as "Natural Gas Country."

Sublette County has always been known for its ranching and tourism, but driven by the huge Jonah natural gas field in the southern part of the county, Sublette is rapidly becoming known as "Natural Gas Country."

According to production figures released by the Wyoming Oil and Gas Conservation Commission and BLM geologist Phil Howland, in 1997, Sublette County had the largest volume of natural production of any county in the state. That year, the state produced 1,193 billion cubic feet of natural gas. Of that total, 349.6 billion cubic feet, or 29.3% came from Sublette County.

Approximately two-thirds of Sublette County's natural gas is produced from Exxon's sour gas fields west of LaBarge. Exxon's Riley Ridge and Lake Ridge fields produced a combined 220 billion cubic feet of gas in 1997. However, this "sour" gas is 60% carbon dioxide.

What has really put Sublette on the natural gas map is the phenomenal success of the Jonah Field in the southern part of the county. According to Mr. Howland, at the end of 1997, there were 58 producing wells out at Jonah. That year the field produced 37.3 billion cubic feet of natural gas and 357,000 barrels of oil for an approximate gross revenue of $68 million.

For 1998, Mr. Howland is estimating that the Jonah Field will have produced 58 billion cubic feet of gas - an increase of 42% - from 100 wells. Add to this 500,000 barrels of oil and he estimates the field grossed approximately $104 million. (He adds that it costs approximately $1.5 million to drill and complete a well at Jonah.)

In just four years, says Mr. Howland, Jonah has become one of the most significant natural gas fields in the state. He predicts that another 30-40 wells will be drilled in 1999. These wells combined with a new pipeline, which will be constructed this summer, will only increase the natural gas flow from the field.

That's not all. The operators drilling wells at Jonah have found the western and southern edges of the field, but not the eastern edge. Recently, Amoco completed a well probing this eastern edge. The well, Antelope 15-4, is located just west of HWY 191 and it flowed 14 million cubic feet of gas in a recent 24- hour flow test. The record for the Jonah field thus far is only 16 million cubic feet per day. "If the Jonah field is going anywhere, its going to the northeast," says Mr. Howland.

Given the success of Antelope 15-4, expect Amoco and other operators to drill wells on the eastern side of HWY 191 this summer. This area has already had 3D seismograph work done.

North of Jonah, Ultra Petroleum thinks it's found a major natural gas field on the Mesa and along the Pinedale Anticline. This month the company issued a press release stating that an independent reservoir engineering firm has increased the estimated amount of the "proved plus probable reserves" from Ultra's leases in Sublette County to 432 billion cubic feet of gas. This is a 43% increase since July 1998.

The BLM is currently completing the draft for the Pinedale Anticline Environmental Impact Statement and hopes to release it later this month. The agency is conducting the analysis for up to 700 natural gas wells on the Mesa and Pinedale Anticline.

In 1998, Mr. Howland estimates that the Anticline produced 4 billion cubic feet of gas from its current 20 producing wells.