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Evergreen: Coalbed methane development will differ from pilots Water injection facility will be finished this year, John Tanigawa, company’s Alaska project manager, tells the Alaska Support Industry Alliance; production equipment will be installed on eight to 12 wells to test producibility of coals Kristen Nelson PNA Editor-in-Chief
In 2002 Evergreen Resources Alaska Corp. drilled its first coalbed methane wells at its 72,000-acre Pioneer unit in the Matanuska-Susitna Borough north of Anchorage. In 2003, the company will fracture stimulate the wells, begin testing and do additional drilling.
John Tanigawa, Evergreen’s Alaska projects manager, told the Alaska Support Industry Alliance March 13 that the wells are in two pods, or pilot areas. The company, a wholly owned subsidiary of Denver-based Evergreen Resources Inc., a Lower 48 coalbed methane operator with more than 950 wells in the Raton basin in Colorado, drilled eight Alaska wells last year and set up offices and a yard in Wasilla. In addition to drilling the third pilot this year, the company will also finish its water injection facility, he said.
And the company is going to start testing the coals in the wells it has drilled.
The wells will be fracture stimulated, Tanigawa said, and the company is going to “install production equipment on anywhere from eight to 12 wells this year and we’re going to test the producibility of the wells.”
The company spent some $6.4 million in Alaska last year, he said, and will spent $7-$9 million this year. In addition to its work at Pioneer, the company will continue to evaluate shallow gas leases in the Nenana basin near Delta Junction. Methods the same, technology different Coalbed method development methods are the same as those used for convention oil and gas, Tanigawa said: “We still go out and drill wells. We cement it. We complete it and produce it.”
But the manner in which coalbed methane is developed is different than what Alaskans are used to seeing, because it is based on technology developed in the last decade.
“These are shallow water wells that produce gas,” he said.
Evergreen hopes that coalbed methane will be economic in Alaska, but Tanigawa said there are several challenges. Most are related to the Arctic environment and the remoteness of Alaska, he said, but there are also problems with Alaska oil and gas regulations, which were designed for deep gas wells or for oil wells.
“It’s been a process of trying to work with the regulators to show them how different this is,” he said.
For example, initially Evergreen had to hook up to large blow out preventers for coalbed methane drilling at Pioneer, but now, Tanigawa said, thanks to the Alaska Oil and Gas Conservation Commission, “we’re using more equipment that’s amenable to this kind of work and it’s manual BOPs, much less cumbersome.” Fracturing within the month Evergreen is a vertically integrated company with its own drilling, cementing, fracturing and completing equipment. Tanigawa said that fracturing, “pumping sand, water and nitrogen at pressures and rates high enough to crack the rock,” will begin at the Pioneer unit wells within the month.
Commercial production is another matter.
“Coalbed methane takes several years to evaluate,” Tanigawa said, and the wells will “have to produce a lot more than a few hundred Mcf (thousand cubic feet) a day per well just to cover costs.”
He said the company could start having production as early as this year. “It requires no processing other than just taking out water,” he said. Coalbed methane doesn’t require a gas processing plant.
It will, however, require pressurization. The coalbed methane is collected at about 30 pounds per square inch pressure, he said, and the Enstar pipeline it would go into runs about 700 psi.
“So we would need to compress it.” Testing denser than production The company has drilled two pods of pilot wells, with wells about 700 feet apart.
“Coalbed methane won’t be developed this densely,” Tanigawa said. Field development would probably be one or two wells every quarter section, he said.
Evergreen is targeting both Tyonek coals and Tyonek sandstones and found an average of 138 feet of coal, with the area prospective for coals from about 250 feet down to maybe 5,000 feet. Tanigawa said the technically feasible depth limit for production is probably about 4,500 feet. As you go deeper, he said, the permeability of the coal decreases because of the greater stress on the coals. Evaluation in Nenana basin Evergreen continues to evaluate gas potential in the Nenana basin near Delta Junction, Tanigawa said. The company is shooting seismic there now and plans to compete that program in March.
There is a lot of coal, he said, and “we’re trying to determine if the coals are of sufficient quality … if they have enough gas.” The other issue, he said is if the coals “have enough cleating so that there is sufficient permeability.”
Exploration in the Nenana basin would be done with a rig that can be moved by helicopter.
In addition to the seismic survey in the Nenana basin, a gravity survey is also planned and more field geology.
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