North Slope likely has 211 tcf undiscovered gas

USGS’s Houseknecht predicts big increase in northern Alaska’s undiscovered, recoverable gas resource estimate when agency submits final numbers late this year

Kay Cashman

Petroleum News Publisher & Managing Editor

When the U.S. Geophysical Survey releases its final numbers for northern Alaska’s undiscovered, technically recoverable, natural gas the average estimate is likely to reach 211 trillion cubic feet.

USGS has already released its estimates for undiscovered, technically recoverable gas on federal lands and offshore state lands – 150 tcf. At the end of this year the agency will publish its estimates for onshore state and Native lands.

David Houseknecht, one of USGS’s top research geologists, expects those numbers to be close to the average estimate for federal lands in the National Petroleum Reserve-Alaska, 61.4 tcf, bringing the average estimate of undiscovered, technically recoverable gas in northern Alaska to approximately 211 tcf. (USGS provides a range of undiscovered resources based on probability, the ‘mean’ or average number being the most likely.)

The 211 tcf estimate does not include the 33 to 35 tcf of known (proved) reserves in North Slope fields such as Point Thomson and Prudhoe Bay.

“The largest accumulations we expect in the National Petroleum Reserve-Alaska are approximately the same size as the known gas reserves in the Point Thomson field. They are pretty substantial accumulations,” Houseknecht said in his presentation at the legislative gas hearings in Anchorage on July 28.

“Every one of those four major gas plays in NPR-A extends across the Colville River into Native and state lands. They extend all the way eastward to the pipeline corridor.

“So even though we have not finalized our estimates for state and Native lands and I therefore cannot be specific, the geology on state and Native lands is essentially identical to that of the National Petroleum Reserve-Alaska and it would not surprise me if, in a few months from now, we are releasing numbers that are the same order of magnitude as our NPR-A estimates,” he said. USGS estimates in NPR-A were 40.4 tcf to 85.3 tcf, with an average undiscovered, technically recoverable, gas resource of 61.4 tcf.

“The upside potential could be much greater,” Houseknecht said.

According to a chart supplied by Mark Myers, director of the state Division of Oil and Gas, for his presentation at the gas hearings, with 150 tcf of gas reserves you could fill a gas pipeline delivering 5.6 billion cubic feet a day for 75 years.

Nonconventional gas not included

USGS is ignoring unconventional resources in their current estimates because their “recoverability potential has not been established,” Houseknecht said.

He cautioned that USGS’s gas resource estimates, although based on sound science, have not been confirmed by drilling. Proved gas reserves, however, are resources that have “been shown to exist in known reservoirs” and can be “expected to be produced.”

Although USGS assessments are done independent of state governments, there is cooperation between the two in terms of sharing available geological and geophysical data, Myers said.

“Resource assessments are always on-going. As you get more information, as you get more understanding. Traditionally, assessments on the North Slope focused on oil. Now we’re seeing a more dedicated effort to look at gas resource potential,” he said.

Does Myers think Houseknecht’s gas resource estimates for northern Alaska are accurate?

“I think … its’ highly probable the gas resources are there,” he said.

How do northern Alaska’s undiscovered gas reserves compare to the deepwater Gulf of Mexico, a major contender for oil and gas capex spending?

The U.S. Minerals Management Service estimates there is “as much as 55 tcf of undiscovered natural gas” in the deepwater frontier of the Gulf (water depths greater than 7,000 feet).

Editor’s note: See part two if this story in the Aug. 8 edition of Petroleum News.