The Spanish oil company Repsol has decided to plug and abandon its Qugruk Number 2 well a month after it was damaged in a shallow gas blowout.
Repsol's decision to give up on the well and cap it with cement was the right choice, said Cathy Foerster and Dan Seamount, two commissioners on the Alaska Oil and Gas Conservation Commission.
"The best thing they could do is abandon that hole," said Seamount, a geologist.
In a situation report issued Tuesday afternoon, the Alaska Department of Environmental Conservation said attempts to control the well by pumping heavy mud into it were stymied by rock obstructions between the drill pipe and the formation it passes through.
To be effective at lubricating the drill, bringing cuttings to the surface and containing pressure in the well, the mud must circulate down and up the hole. The rock bridges prevented circulation, the DEC said.
The blowout occurred Feb. 15, when Repsol's exploratory drill rig, on the Colville River delta about 18 miles northeast of Nuiqsut, hit an unexpected pocket of pressurized gas while boring 2,523 feet below the surface. About 42,000 gallons of drilling mud shot out of the hole and through a diverter about 75 feet from the rig, contracted from Nabors Drilling. With the mud came natural gas.
To avoid the risk of fire, the rig was shut down and quickly froze in sub-zero temperatures. Gas flowed out of the hole until about 9 p.m. on Feb. 16, when it stopped on its own. Even though nothing more leaked, the well hasn't been considered under control.
Some of the spilled mud, a clay mixture, was cleaned up while workers struggled for days to thaw the rig, but full cleanup can't begin until the well is formally declared under control, the DEC said.
Repsol, a relatively new player on the North Slope, is seeking approval from the Alaska Oil and Gas Conservation Commission for the final capping plan. While the commission hasn't ruled yet, Foerster, an engineer, said in an email that "abandoning the well is the best next move."
Repsol is drilling another exploration well, the Kachemach 1, about 40 miles southwest of the Kuparuk base camp. The company suspended drilling after the Qugruk blowout, but resumed March 8.
The AOGCC suspended other permits previously issued for the company.
"We wanted to re-look at it and make sure there wasn't anything they were missing," said Seamount, of the AOGCC. "We wanted more detail in their plans."
Repsol spokeswoman Jan Sieving said in an email that the company was resubmitting permits for Qugruk 1 and Qugruk 4.
"If approved, we will look at drilling them this year," though the short drilling season may force a postponement till next winter, she said.
Reach Richard Mauer at email@example.com or 257-4345.