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Questions over potential gas storage leaks
In a Regulatory Commission of Alaska hearing over certification of a new underground gas storage facility on the south side of the city of Kenai some testimony and much cross-examination time was devoted to discussions of whether the facility would securely store gas, or whether there would be a possibility of gas leaking, either to some undesired underground location or perhaps to the surface.
Cook Inlet Natural Gas Alaska, or CINGSA, plans to bring the new facility on line in 2012, using a depleted gas reservoir in the Sterling C sands of the Cannery Loop gas field. Regulatory oversight of the integrity of the Sterling C sands as a storage reservoir is primarily the responsibility of the Alaska Oil and Gas Conservation Commission and the question of potential leakage from CINGSA’s planned facility was extensively discussed during a recent AOGCC hearing.
However, the question of gas leakage is also of interest to RCA because any costs resulting from the loss of gas or from the impact of gas leakage on storage facility operations would likely be passed on to the consumers of Southcentral Alaska utility gas.
Vincent Goddard, president of Inlet Fish Producers of Kenai, whose business facilities sit over part of the proposed Sterling C storage reservoir, has been relentlessly raising questions over the physical integrity of the planned storage reservoir, saying that the possibility of the leakage of gas from the reservoir to the surface poses a significant safety risk to his businesses and to local residents.
In particular, several old gas wells in the area, most of them accessing gas sands in the Beluga formation below the Sterling C sands, penetrate the Sterling C reservoir. These wells were plugged and abandoned years ago and could act as conduits for gas to leak from the storage reservoir, Goddard and some technical experts he has called on as witnesses have claimed. CINGSA needs to remediate all of the wells that penetrate the reservoir before starting construction of the storage facility, said one of Goddard’s witnesses, John Robertson, a professional engineer with 25 years of experience in evaluating oil, gas and mining projects.
CINGSA, following its own research into the integrity of its planned storage reservoir, has committed to remediate one of the old wells but has said that an engineering evaluation of the other wells has indicated no potential for leakage.
Pressure history Tom Walsh, a managing partner of Petrotechnical Resources of Alaska, the company that is the primary subsurface consultant for CINGSA, said in testimony to RCA that the pressure history of gas in the Sterling C sands before and during gas production from the sands, as part of the Cannery Loop gas-field operations, had unequivocally indicated no migration of gas in or out of the sands, thus demonstrating the excellent integrity of the Sterling C reservoir. And CINGSA does not plan to raise the underground gas pressure above the natural gas pressure that existed in the reservoir for perhaps millions of years before the Sterling C sand was produced.
“There is no risk of gas escaping to the surface,” Walsh told the commissioners during cross examination on Nov. 12.
Richard Gentges, CINGSA project manager and a gas storage reservoir engineer with 29 years of experience, told the commission that the possibility of gas migration from the Sterling C reservoir was extremely remote and that CINGSA had conducted a detailed engineering evaluation of all wells that penetrate the reservoir.
—Alan Bailey
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