Repsol works to thaw rig after gas blowout
Repsol E&P USA was working Feb. 22 to get its drill rig operational and the company’s Qugruk 2 exploration well in the Colville River delta on the North Slope back under control after a shallow gas blowout, officials with the Alaska Oil and Gas Conservation Commission said.
The company Feb. 15 experienced a gas “kick” and gas release at the well, and the rig was evacuated. The flow of gas ceased late the following day, Thursday, and since then Repsol and its drilling contractor, Nabors Alaska Drilling Co., have worked to assess the rig condition and get equipment thawed and operational, according to Jim Regg, senior inspector with the Alaska Oil and Gas Conservation Commission.
Repsol and Nabors had not yet installed a blowout preventer on the well because the “surface casing,” the uppermost section of the well equipment, had not yet been set and cemented, Regg said. After the surface casing is installed the blowout preventer is installed.
Meanwhile, a gas “diverter” is put in place on the rig so that if gas is encountered at a shallow level, which happened in this case, the gas can be safely diverted.
Thawing operations started Feb. 20, Regg said.
“They started thawing equipment yesterday and it’s going to take them some time to get this done. They are being very meticulous about this, and very mindful of safety,” Regg said.
Some equipment on the rig may have to be repaired, he said.
No injuries or fire resulted from the incident. Drilling mud was blown from the well, however. Repsol reported that about 42,000 gallons of water-based drill fluid, or 1,000 barrels, were spilled from the well. The well cannot be considered under control until the rig is operational, however.
Houston-based Wild Well Control Inc. is working with Nabors and Repsol.
In a situation report released Feb. 20, the state Department of Environmental Conservation said, “Well control workers have set up boilers outside the rig and begun using steam to thaw frozen drilling mud and water from around the drill cellar access doors. Thawing operations will first focus on gaining access to hydraulic lines and other equipment in the drill cellar that are essential to operating the well.
“Frozen material in the drill cellar is several feet thick, and at this time crews are not able to estimate how long it will take to complete the necessary thawing operations,” the DEC said in the report.
Meanwhile, cleanup operations near the rig have begun.
“Nabors Drilling and Cruz Construction Inc. workers have removed approximately 200 cubic yards of drilling mud and contaminated snow from areas adjacent to the east, north, and west sides of the drilling rig. This will improve access for crews and equipment working to cleanup and repair the rig,” DEC said in its situation report. “Due to the potential danger posed by the gas diverter in the event the well resumes flow, no cleanup will take place on or off the pad to the south of the rig before well control work is complete.”
Regg said that currently, there is no gas being released form the well, but that the gas diverter is still in place.
Gas blowouts from shallow gas pockets have occurred previously on the North Slope. Methane hydrates are known to exist in the area and are believed to have contributed to previous shallow gas blowouts.
Cathy Foerster, a commissioner with the AOGCC, said the agency will investigate circumstances of the blowout after the situation has normalized. One area of inquiry will focus on why a shallow hazard survey, which is done prior to the start of drilling of an exploration well, did not show the presence of the gas pocket, Foerster said.