Cook Inlet: Oil Platforms Powered by Leaking Alaska Pipeline Forced to Shut Down

The owner of an underwater pipeline spewing natural gas into Cook Inlet is taking steps to reduce the leak three months after it started.

A natural gas pipeline has been leaking since at least late December into Alaska's Cook Inlet, home of endangered beluga whales, and the company says it can't safely stop the flow of gas. Credit: James Brooks, flickr

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The company responsible for a pipeline spewing almost pure methane into Alaska’s Cook Inlet for at least three months is taking significant steps toward stopping the leak. That includes shutting down the offshore oil platforms powered by the pipeline.

Hilcorp Alaska announced on Saturday it will also lower the pressure in the underwater line, from 145 psi to approximately 65 psi, until it can be fixed. The company said that is the minimum amount of pressure needed to keep the line running. Stopping the flow could trigger a more dangerous crude oil leak into the inlet, a protected habitat for endangered beluga whales and other species.

The decision came after discussions between Hilcorp, Alaska Gov. Bill Walker and the state Department of Environmental Conservation.

“I appreciate that the company officials are implementing a prudent plan of action,” Walker said in a press release. “Alaskans want peace of mind that our waters are protected.”

The natural gas leak was first reported on Feb. 7, but the company later discovered that it probably started in late December. Hilcorp can’t send divers to fix the leak because the inlet is clogged with ice, which is expected to remain for a few more weeks.

The company submitted its first environmental monitoring report last week, which showed that oxygen levels near the leak were lower than in other parts of the inlet and that methane levels were high enough to endanger fish. The first samples were not taken close to the leak site, however, so the leak could be causing a worse environmental impact, according to Alaska environmental officials.

Adding to concerns is that as April approaches, so does the beginning of spring migrations for birds and fish to the inlet.

The pipeline carries natural gas from shore to four oil platforms. The produced oil is then carried from the platform back to shore via an adjacent pipeline. Both are 8-inch lines that are 52 years old. The federal Pipeline and Hazardous Materials Administration gave Hilcorp until May 1 to either fix or shut down the gas pipeline. It issued a separate order requiring Hilcorp to inspect the safety of the oil pipeline, which the agency said could be vulnerable to a leak.

Just two of the oil platforms are actively producing oil. After Hilcorp lowers the pressure in the line, production on both will be stopped. (The other two drilling platforms are in “lighthouse mode,” meaning the wells have been decommissioned and are no longer producing.)

“Shutting in wells and idling lines and equipment in very cold temperatures create a known risk of freeze-up and potential rupture,” Hilcorp wrote in a press release. “Warmer ambient temperatures now permit a safer shut in process of the wells along with the associated lines and equipment.”

Hilcorp said the shut-in procedures will begin as soon as its plans are approved by regulators.

The company has become the primary oil and gas producer in Cook Inlet in recent years, and has a checkered safety record in Alaska and elsewhere in the United States. The Houston, Texas-based company is also active in gas development in the Utica Shale in Ohio and Marcellus Shale in Pennsylvania, and was a major player in the Eagle Ford Shale of Texas. It has operations on the Gulf Coast of Texas and Louisiana, and has recently started to expand into the North Shore of Alaska, as well as the Arctic.