Apache Corp. has detected an underground flow of natural gas at the site of a shallow-water exploratory well in the U.S. Gulf of Mexico, the company and U.S. regulators said.
Apache evacuated 15 nonessential workers and shut in the well, located about 50 miles east of Venice, La., after the company prevented a blowout at the well. About 50 workers remained on board, and there were no injuries.
In a statement posted on its website Thursday, the Bureau of Safety and Environmental Enforcement, which oversees the safety of offshore energy operations, said Apache successfully activated the blowout preventer aboard the jack-up rig to stop natural gas from flowing to the surface. No gas or other pollution has been detected at the location, but additional testing found an underground flow of natural gas, the BSEE said.
A blowout preventer is a tall stack of valves that can supply thousands of pounds of pressure to seal off a well in case of an emergency. The 2010 Deepwater Horizon accident, which has been attributed to a combination of factors including a failed cement job at the bottom of the well and a blowout preventer that failed to close, prompted an increase in regulatory scrutiny in the Gulf. That has included stricter blowout-preventer inspection and maintenance requirements.
In a statement, Apache said natural gas began flowing from the well during drilling operations on Feb. 4. Tests revealed natural gas had migrated from the bottom of the well, about 8,261 feet below the seafloor, to a sand formation about 1,100 feet below the seafloor. The rig was drilling in 218 feet of water.
Michael Bromwich, the former director of the BSEE, said it appeared the company and the government acted properly, but the incident is a sobering reminder that offshore drilling is a risky business.
The incident "undermines the often-repeated but erroneous claim that drilling in shallow water has few risks, and reinforces the conclusion that heightened safety and environmental standards should be applied across the board," Mr. Bromwich said in an email.
Apache said it is now working with well-control experts to stop the flow of natural gas below the seafloor. At the BSEE's direction, Apache is readying another rig to bring to the site in case a relief well needs to be drilled.