State and federal agencies respond to spill of light oil on North Slope

State and federal regulators are investigating the cause of a leak of light oil at the Point Thomson field on Alaska’s North Slope that was discovered Saturday.

The leak, about 35 miles east of Prudhoe Bay, is estimated to be up to 275 barrels of liquid natural gas condensate, known as light oil.

The product spilled from the 22-mile export pipeline that helps carry the light oil to market, the Alaska Department of Environmental Conservation said in an initial report Monday. The spill stretched about 225 feet long and 20 feet wide.

Harvest Alaska, an affiliate of Hilcorp Energy that operates the pipeline, is the “potential responsible party,” the state report says.

“We had fortunate weather circumstances,” said Kimberly Maher, the state’s on-scene coordinator for the response. “At this time, there’s no known impact to any wildlife in the area.”

Preparations for the cleanup are being mobilized, she said.

Hilcorp took over operation of the Point Thomson field in 2022 from ExxonMobil.

Hilcorp also operates the giant Prudhoe Bay field on the North Slope after expanding quickly in Alaska in little more than a decade. Hilcorp has incurred a number of fines from state oil field regulators, who have multiple times called out the company for a track record of regulatory noncompliance.

The leak was discovered Saturday evening by a leak detection system, said Andrew Limmer, vice president of Harvest Alaska, in a prepared statement.

“We took immediate action by shutting down the pipeline and promptly notified the relevant federal and state agencies,” the statement said. “Currently, we are conducting a thorough assessment of the incident ... and response personnel have begun cleanup operations.”

Harvest reported the suspected leak to state regulators early Sunday morning, about four hours after receiving the leak alarm, according to details from the state.

Aircraft were used to confirm the leak on Sunday shortly before noon, the state report said. A ground survey crew provided more visual confirmation after that.

Harvest Alaska reported that the maximum amount released from the spill is 275 barrels of condensate, the statement said.

The maximum estimate is based on the full quantity of oil that the relevant segment of the pipeline can support, Maher said.

The exact size of the spill is impossible to know right now, she said early Tuesday.

The spill happened about a mile southeast of the Badami field, an area where the Point Thomson pipeline connects to the Badami pipeline.

The Point Thomson pipeline was built about a decade ago.

It’s a key part of the challenging Point Thomson field, which began production in 2016 after decades of regulatory and legal battles between the state and ExxonMobil over the lack of production. The $4 billion development of the field, located near the Arctic National Wildlife Refuge, was heavily subsidized with state tax subsidies.

The reservoir is highly pressurized, complicating the production of the condensate that is made from natural gas.

In recent months, the field has produced less than 3,500 barrels of light oil daily, state records show.

That’s a tiny fraction of overall North Slope daily production of roughly 470,000 barrels of oil.

Harvest has “stood up” an incident management with a unified command that includes the Alaska conservation department and the U.S. Coast Guard.