Slope well review reveals no issues beyond those flagged by BP

An emergency engineering review of all North Slope wells ordered last October by state regulators did not reveal any significant issues but a regulation change is still likely.

The Alaska Oil and Gas Conservation Commission issued the emergency directive to North Slope production and exploration companies Oct. 30 after it was determined a BP well at Prudhoe Bay Drill Site 2 that failed and sprayed about 100 gallons of oil last April did so largely due to its outer surface casing being set in the permafrost — and the permafrost thawing and subsiding.

The commission, which regulates all of the highly technical subsurface oil and gas activities in the state, ordered all wells found to have similar construction to be shut in by Dec. 31.

BP had previously plugged five producing wells at Prudhoe after its own review spurred by the April leak, according to a company spokeswoman.

The hot fluids produced from a well can melt the surrounding permafrost, causing the thawed water to drain away and leading the ground to sink. That gradually puts the outer well casing under a compression load, which combined with other pressure and temperature affects, can cause the casing to fail, according to BP’s report to the commission on the well failure.

AOGCC Commissioner Cathy Foerster said in a brief interview that every operator did the evaluation and reported back to the commission, which found there are no other wells with construction characteristics mirroring the failed well other than those previously reported and shut in by BP.

ConocoPhillips, operator of the large Kuparuk and Alpine oil fields, has a handful of wells with casings set in the permafrost, but other elements of construction necessary for the failure to occur aren’t present in those wells, according to Foerster.

According to AOGCC records, there are more than 3,700 wells on the Slope, of which, nearly 1,600 are active production wells. The rest are injection, disposal or idle production wells.

Despite the good news from the well review, the commission is proposing a regulation change that would require the surface casings of all future wells to be set below the bottom of the permafrost to prevent history from repeating itself.

“Just to make sure that after this set of commissioners and engineers are gone in the future it can’t happen again we’re going to prohibit setting that casing string in the permafrost,” Foerster said.

No one showed up to testify at a Jan. 4 public hearing to discuss the regulation change.

“Usually what we do is pretty boring and this is just another example of that,” Foerster added.

Elwood Brehmer can be reached at elwood.brehmer@alaskajournal.com.

Updated: 
01/25/2018 - 3:13pm

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