The state is reviewing the “mechanical integrity” of Prudhoe Bay wells operated by BP after a well in December “jacked up” and struck the roof of a well house, releasing gas and a small amount of oil in a incident that appears similar to an unusual 2017 leak at a nearby well, officials said.
That April 14, 2017, leak was blamed on permafrost that had melted from hot production fluids, causing the ground to subside and put dangerous pressure on pipes in the well.
The recent Dec. 6 release appears to be a “failure event” that is “similar” to the uncontrolled release of well fluids in the 2017 incident, said a mid-December letter from Hollis French, chair of the Alaska Oil and Gas Conservation Commission, to Janet Weiss, head of BP in Alaska.
Now, the AOGCC has a long list of questions for the oil company, including the “current state” of ground subsidence throughout the Prudhoe Bay oil field, and how many wells have failed integrity tests because of subsidence.
The agency has set a hearing on the matter for Feb. 7.
Given the breadth of the state’s request for information, BP is expected to request a later hearing date, according to documents provided by the agency on Friday.
Records indicate the leak began late Dec. 6. It was stopped after two full days, on Dec. 9, said Megan Baldino, a spokeswoman with BP in Alaska.
“BP immediately reported the incident in accordance with state and federal laws,” she said.
No one was injured, and the oil that leaked was confined to the “immediate well-house area” and did not impact tundra, she said.
BP is investigating the incident.
Tom DeRuyter, state on-scene coordinator for the Department of Environmental Conservation, said on Friday that the well -- Well 2 at Drill Site 2 -- apparently rose suddenly, or “jacked up.”
Equipment atop the wellhead struck the top of the well house, damaging a valve seal and causing the leak, he said.
It shares similarities with the 2017 incident at the nearby well, DeRuyter said. In that case, the wellhead and valve assembly jacked up 3 feet and struck the roof of the well house, causing that oil and gas release. A problem with the construction of that well, one of Prudhoe Bay’s original old wells, was that it was anchored to permafrost, rather than more stable rock, French said in late 2017.
The 2017 incident led to a review of North Slope wells and the shut-in of 14 of BP’s “highest risk” wells with similar designs. Shutting them in meant they were suspended from producing oil.
Well 2 at Drill Site 2, site of the recent leak, was one of those shut-in wells, Baldino said.
Following the leak there, that well has been plugged and abandoned, meaning it is permanently closed and sealed, said DeRuyter.
After BP stopped the release and sealed the well, DEC closed the file on its case, DeRuyter said.
The review is in the hands of AOGCC, which oversees issues that include well design, he said.
French, the AOGCC chair, ordered BP on Dec. 31 to plug and abandon all 14 of those highest-risk wells, according to documents in the case.
French would not provide comment on Friday, saying the case is “under adjudication” before the agency.