A blowout preventer may have ignited the fire that caused a Gulf of Mexico rig to partially collapse Wednesday, after a natural gas well blew out, federal authorities reported.
A leak in the natural gas well, owned by Walter Oil & Gas, ignited a fire on a jack-up rig operated by Hercules Offshore late Tuesday night, hours after its 44 workers had been evacuated, according to the Bureau of Safety and Environmental Enforcement.
The ignition source may have been heat generated by the friction of formation sand shooting through the blowout preventer, according to an update to Congress from the Coast Guard. The sand may have traveled on the drill floor and up into the metal of the derrick.
The two Houston-based companies have been working together with Wild Well Control, the Coast Guard and the Bureau of Environmental Enforcement to curb the uncontrolled flow of natural gas from the well.
“We are making preparations to fight the fire at this point,” said Tim O’Leary, a spokesman for Walter Oil & Gas. “We are marshaling pumps and boats with firefighting apparatus.”
No one was injured in the evacuation, and no oil was spilled, O’Leary said.
Two firefighting vessels in the area have been moved to a safe distance from the fire and a third vessel with additional fire-fighting capability has been moved to the site, according to the Bureau of Safety and Environmental Enforcement.
O’Leary said that the cantilever, an appendage of the jack-up rig that moves the drilling equipment over the well platform, has caught fire, but that the fire has not spread to the rest of the rig.
The fire caused the beams supporting the derrick and rig floor of the cantilever to fold and collapse over the rig structure, the Bureau of Safety and Environmental Enforcement said. The offshore support vessels were unable to get close enough to safely put water on the rig, the Coast Guard said in an update.
Operators lost control of the natural gas well early Tuesday in the South Timbalier Block 220 in the Gulf of Mexico, while doing completion work on a sidetrack well to prepare for production. All 44 personnel from the Hercules 265 jack-up rig were safely evacuated, the company said.
“We are not focusing on the cause of the spark,” said Eileen Angelico, a spokeswoman for the Bureau of Safety and Environmental Enforcement. “All of that is going to be part of an investigation that has started into the loss of well control event. Right now, we are focusing on the fire and the securing of the well.”
Any incident that involves an uncontrolled flow of hydrocarbons is likely to ignite, according to Brian Kalinec, owner of Kalinec Enterprises, a geophysicist consulting firm.
“Any kind of a spark or friction, especially if the surrounding air is dry, could start a fire,” Kalinec said. “It is like lighting a match and throwing it towards gasoline. It is highly flammable, so a spark could have caused it, if there is no other explanation.”
The Bureau of Safety and Environmental Enforcement is directing Walter Oil & Gas to begin preparations to move a jack-up rig on location to potentially drill a relief well.
The relief operation’s challenge will be to establish the flow path of the natural gas and then figure out the best way to mitigate it, according to Bud Danenberger, a consultant and former chief of offshore regulatory programs at the Minerals Management Service, which has been reorganized into the Bureau of Safety and Environmental Enforcement.
“Their options are a surface operation – which would be hazardous under the circumstances – or a relief well,” Danenberger said. “In many ways it is much more dangerous to deal with a shallow water operation than a subsea well. In a deep-water operation, the emergency personnel are safely removed from the well and using operating equipment remotely. At 5,000 feet above, you are running a joy stick as opposed to being right there where the fire is and running the risk of a structure collapsing.”
While the source of the leak is still unknown, Danenberger explained that there are several possibilities. The flow path could be inside production casing or tubing.
Another flow path could be between the casing strings or the space between the two concentric casing strings. Alternatively, it could be outside the casing, back to the seafloor, either through cement channels or through fractures in the sediments.
“The fact that there is a fire would imply that that is flowing inside the casing or between the casing strings, because it is coming back up to the surface to the rig,” Danenberger said.
The next steps for the operation will hinge on how the well was constructed.
“I would hope that there is enough well bore and well integrity that they can apply a surface cap and then pump in mud and cement or make some connections to pump in heavy mud, but I have no idea what the well flow is,” Danenberger said. “They could either shut in one or more rams of the blow out preventer and pump in mud and cement or if there is some issue with it, perhaps install a surface cap with outlets that would allow them to pump in mud and cement. This is all contingent on the integrity of the well bore.”
The Bureau of Safety and Environmental Enforcement inspectors had initially reported a dissipating light sheen on the Gulf surface on Tuesday, 50 feet by one-half mile in size.
The well is 55 miles off the coast of Louisiana in 154 feet of water, Walter Oil & Gas said.
The rig was working on a sidetrack well — drilled adjacent to an existing one — in preparation for production, the safety bureau said.
The two companies have emphasized the focus on safety in efforts to control the well.
“Our first and foremost concern is for the safety of all personnel aboard our drilling rig and we have taken every necessary precaution to safely evacuate the rig,” said John T. Rynd, CEO and President of Hercules Offshore, in a written statement. “Furthermore, efforts are ongoing with our client, Walter Oil & Gas, to mobilize the necessary resources to regain control of the well and minimize any potential impact on the environment.”
The accident comes on the heels of a Talos Energy well leak earlier this month. Responders stopped the leak after four days, installing a metal plug and pumping cement into the site.
In 2010, BP’s Macondo well blew, releasing an estimated five million barrels of oil into the Gulf of Mexico before the well was successfully contained.