JUNEAU, Alaska (AP) — ConocoPhillips Alaska has attributed the release of natural gas at one of its North Slope drill sites earlier this year to a broken barrier during construction of a waste disposal well, when pressure limits were exceeded during freeze protection operations.

The company describes what occurred as “a unique event, with nothing similar ever occurring at a ConocoPhillips Alaska site.”

An investigation into the matter by the Alaska Oil and Gas Conservation Commission, which oversees oil and gas drilling in the state, continues, said Samantha Carlisle, a special assistant with the agency.

“Because the investigation will be thorough and comprehensive,” the commission does not have a projected timeline for when the probe will be completed, she said by email.

ConocoPhillips Alaska last month said a shallow gas reservoir that the disposal well had come in contact with was the source of the gas release. The disposal well was intended to be used for the regulated disposal of oil field waste, according to a video released by the company, which noted the company had started drilling operations on the well in late January.

The gas release was first detected on March 4. The company, in a statement this week, said that by March 8, it had “secured the location, determined the most probable gas source, and established a controlled flow path for the gas” into its central facility at the Alpine development. The flow of gas from the source was stopped as of March 29, it said.


The waste disposal well has been cemented to the surface, the company said.

ConocoPhillips Alaska said no gas had been detected beyond the CD1 pad, “no recordable injuries were reported, no damage to the tundra was observed and no wildlife impacts were reported.”

The company says it will incorporate findings from its investigation into future projects.