From the pages of
Sublette Examiner
Volume 3, Number 4 - April 24, 2003
brought to you online by Pinedale Online

Industry has long history in county

by Cat Urbigkit

The Bureau of Land Management's Pinedale Resource Management Plan planning area has produced more than 201 million barrels of oil and 5.6 trillion cubic feet of gas since the 1920s. In fact, seven of Wyoming's top 25 gas fields are within this area: Jonah (2), Fogarty Creek (3), Lake Ridge (6), Tip Top (16), LaBarge (21), Hogsback (22), and Birch Creek (23). Jonah was also the state's second-largest oil producer in 2001.

Since 1990, for every four wells that were drilled, one was plugged and abandoned. Prior to 1950, 428 wells were drilled in the area, and since 1970, nearly 2,500 more wells were drilled.

The average total depth of wells in this area has increased from 6,500 feet in 1990 to 10,200 in 2001, reflecting greater drilling depths in the Jonah field and the Pinedale Anticline areas.

Within the RMP boundary, 3,722 wells are present, including 1,527 plugged and abandoned wells, 1,963 completed wells, 103 dormant wells, 22 abandoned wells and 107 in the process of drilling, according to the report.

Drilling activity has concentrated in three regions: the Greater Big Piney/LaBarge area, which has had the most activity; the Jonah Field; and the Pinedale Anticline.

While natural gas production was flat in the 1970s and early 1980s, production has steadily increased since 1985. The start up of Exxon's Shute Creek gas plant in 1986 was responsible for the six-fold increase in gas production. The plant processes gas from 21 deep wells (15,000 to 16,0000 feet) that produce high-volume, poor-quality gas from the Madison Limestone, according to the report.

Gas production from the Pinedale RMP area is now 27 percent of Wyoming's total gas production.

Oil production in this area is relatively minor compared to gas production, but recent increases are due to condensate produced in association with gas from the Jonah Field.

In 1907, oil seeps were discovered in the Big Piney/LaBarge region, eventually leading to the development of the LaBarge Field in 1924, which initially produced oil from shallow, lower tertiary reservoirs.

"The first significant gas was encountered in 1938 when a well drilling in tertiary rocks at a depth of about 1,700 feet 'blew out' (i.e., uncontrolled flow to the surface) at a rate of between 22 to 77 million cubic feet of gas per day," according to a BLM mineral report. Development continued in the area until after World War II, but it occurred in the deeper Frontier Formation. In later years, deeper production from different formations occurred.

"In 1962, Mobil drilled the deepest well on the platform up to that time (over 15,000 feet deep) to Cambrian Limestone," the report stated, discovering carbon dioxide in the area (especially in the Madison Limestone), which was eventually put into production in 1986 by Exxon Corporation.

The Madison Limestone reportedly produces gas from a thick, extensive section of carbonate sediments, averaging 850 feet thick on the crest of the LaBarge platform. The Madison Limestone Reservoir appears to be productive over an area of about 21 miles by 65 miles in a structural trap, the report noted, while the LaBarge Platform is essentially a large anticline.

There are a number of fields in the Big Piney/LaBarge vicinity that have coalesced into one large producing area, the report stated, adding that to date, these fields have produced most of the oil and gas in the RMP planning area.

The Pinedale Anticline is roughly 35 miles long by six miles wide. According to the mineral potential report, the California Company drilled the first structure in 1939. This wildcat well was drilled to about 10,000 feet, but no commercial production was established at that time.

But in the 1950s, El Paso Natural Gas Company drilled a number of wells on the anticline, including Wagon Wheel No. 1, which was drilled to a total depth of 19,000 feet in the Baxter Shale. Until 1989, only 20 wells were drilled on the anticline, with production hampered by the low-permeability reservoirs and hydraulic fracturing used to stimulate the wells that had not provided the expected results, the report stated.

"By the early 1990s, industry operators began to understand that previous well fracturing and treatment techniques were actually reducing productivity of the reservoirs," the report stated. "New treatments at the Jonah Field (adjacent to the anticline) spurred operators to redesign well treatment and stimulation at the anticline."

By this time a year ago, there were 21 active, producing wells and 12 shut-in wells on the anticline. The report stated that since the end of 2000, the cumulative production nearly doubled from just over 12 billion cubic feet of gas to 22.9 billion cubic feet of gas at the end of February 2002. Production is coming from several different formations.

The first well in the Jonah Field area was the Wardell Federal Unit No. 1 drilled by Davis Oil Company to a total depth of 11,324 feet in 1975, according to the mineral report. The well was shut-in because of low flow rates and the absence of a pipeline connection. The area was assigned the name Jonah Field in 1977 although the field had no production, according to the report.

Homes Petroleum Corporation drilled another two wells in the area in 1986, but there were problems with the wells and resulting marginal production. Eventually, McMurry Oil Company purchased lease rights in 1991. This company reportedly employed better drilling and completion techniques to increase productivity and was very successful. McMurry's initial Federal 1-5 well had a stabilized flow rate of 3.7 million cubic feet of gas per day and 40 barrels of oil per day after a week of production testing.

Although the Jonah Field was initially thought to be a basin-centered gas accumulation, step-out wells eventually helped determine that there was an element of fault trapping to the field.

"Jonah Field is essentially a fault-bounded pressure compartment in that over-pressuring occurs at depths that are 3,000 feet less than areas outside of the bounding faults," the mineral potential report stated. "In addition to the bounding faults, the producing sandstones in the field area may be of limited extent and there are fault compartments in the area inside of the bounding faults, further adding to the complexity and reservoir heterogeneity of the field."

The mineral potential report stated that by November 2002, 435 wells had been completed in the Jonah Field, with only five of these being plugged and abandoned. Cumulative production as of last November was 645 billion cubic feet of gas, 7.3 million barrels of oil and 2.2 million barrels of water. The report estimates that ultimate recovery from the field is expected to be 1.5 trillion cubic feet of gas based on 40-acre well spacing, but could be as high as 3 trillion cubic feet. In addition, according to the report, "Additional significant reserves of gas may be present in untested zones on the field."

The Pinedale RMP planning area has also been subject to 46 deep wells - that is, wells drilled to depths greater than 15,000 feet. The deepest well drilled was the Wagon Wheel No. 1, which is located just off Highway 351 and was drilled to 19,000 feet on the Pinedale Anticline Field.

Thirty-five of the 46 deep wells were originally completed as gas wells, and most produce from zones deeper than 15,000 feet. All production in these deep wells has been from the Madison Limestone, according to the report, and there has been no oil production from these wells.

The LaBarge Platform is home to most of this area's deep wells, with 33 concentrated in the Fogarty Creek, Lake Ridge, Riley Ridge, Tip Top, Graphite and Hogsback III fields that lie of the crest of the platform, according to the report.

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