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Wainwright’s coalbed methane potential huge, could provide local energy Farther east coalbed methane underlies the proposed southern gas pipeline route, and could be shipped in gasline along with conventional gas Kristen Nelson PNA Editor-in-Chief
Natural gas is a known resource on the North Slope and is reinjected at Prudhoe Bay, shipped down the pipeline as natural gas liquids and used to for enhanced oil recovery across the slope.
But in addition to this conventional natural gas, associated with crude oil, three non-conventional gas sources — hydrates, shales and coal — are also being studied.
Shale gas is being evaluated for use at the Red Dog zinc mine near Kotzebue and gas hydrates are in the early stages of evaluation at existing oil fields.
A third non-conventional gas source, coalbed methane, is the target of a program of the U.S. Geological Survey, the Alaska Division of Geological and Geophysical Surveys and the federal Bureau of Land Management, USGS senior research geologist Charlie Barker said May 22 in Anchorage.
The agencies are evaluating Alaska’s coalbed methane potential for both rural and commercial use, Barker said at a joint American Association of Petroleum Geologists Pacific Section Convention and Society of Petroleum Engineers Western Regional Meeting. Commercial gas would move to market through a pipeline while rural use would be replace diesel for local heating and power generation. Both activities, he said, are fueled by industry as well as Native corporations and government. Wainwright seismic available The largest coalbed methane potential is in northwestern Alaska on the coast and in the National Petroleum Reserve-Alaska — some 3 trillion tons of coal, approximately one-third of the entire 50 states’ coal reserves, Barker said.
That coal underlies an area including Wainwright on the western side of the North Slope, “one of our objectives for our rural energy drilling program” Barker said.
Numerous seismic lines were shot when the U.S. Navy explored the NPR-A, and one of those seismic lines runs right through Wainwright just west of NPR-A, he said.
There are also coals exposed in the Kuk River Delta, coal has been encountered in test holes and there was coal mine development just north of Wainwright that encountered coal in a test hole at 140 feet. Between that test hole and the seismic, Barker said, the indication is that coal will be encountered below Wainwright from 140 feet down to about 2,000 feet. The Wainwright-area coal is in the Nanushuk formation and Barker said “most of this onshore portion of the Nanushuk is within a drillable range for coalbed methane at approximately above 6,500 feet, which is the limit of produceability in the Lower 48.”
Indications are the coal is gassy, and if coalbed methane can be developed economically, there is a population of around 500 people who could use the energy, he said. Coal along proposed gasline route Wainwright is a long ways from transportation, but “as you all know, they’re proposing to put a gas pipeline” from Prudhoe Bay south, Barker said.
The Sagavanirktok basin along the Sagavanirktok River straddles the proposed southern gas pipeline route. And the Sagavanirktok formation contains coal, Barker said, and “we have the chance to drill.”
Coal along the pipeline corridor would be too costly to transport. “But there’s a huge gas resource that’s available for both rural development and also for exploitation and input into the pipeline,” Barker said.
USGS has cored with a small rig at the Sagwon Bluffs, “but this was still at a time when coalbed methane was not on the scope and so there’s no desorbing data,” he said, referring to measurement of the amount of gas coming off a coal.
Based on estimates of coal in the area, 43 tcf of coalbed methane has been calculated to exist above 6,000 feet subsea around the proposed pipeline, with “8 tcf very close to the pipeline that could probably be drilled from existing pads and gravel pits…,” Barker said. Core drilling possible this year USGS has started the permitting process to drill along the haul road this year.
“We have mobilization money to get our rig out to the North Slope but we don’t have the money to actually drill when we get there, so we can cruise up and down the Dalton Highway.” Barker said July 22 that he didn’t know that drilling had been funded, but understood the money for the project — which has been requested for several years — could have been added to agency budgets. “It would be exciting if we actually attained funding to be the first to measure and publish CBM gas contents in Northern Alaska,” he said.
The LF-70 mineral rig used at Red Dog is what USGS would like to use to drill these core wells. With that rig, drilling could be done at about $100 a foot, Barker said.
Coalbed methane discovered near the pipeline corridor, he said, could be shipped in a gasline along with conventional gas, adding to gas reserves available to go from Alaska’s North Slope to market.
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