Company catches break: Sand and sediment chokes off flow of natural gas well in Gulf

Photo provided by On Wings Of Care -- The burned Hercules 365 rig 55 miles southwest of Grand Isle. Federal regulators said the leaking natural gas well had “bridged over,” meaning that small pieces of sediment and sand had flowed into the well path and restricted the flow of gas and the fire went out. Show caption
Photo provided by On Wings Of Care -- The burned Hercules 365 rig 55 miles southwest of Grand Isle. Federal regulators said the leaking natural gas well had “bridged over,” meaning that small pieces of sediment and sand had flowed into the well path and restricted the flow of gas and the fire went out.

A blaze aboard a drilling rig that ignited after a natural gas well blowout in the Gulf earlier this week appeared to have subsided Thursday, as sand and sediment choked off the flow of gas and stopped feeding the fire.

Meanwhile, response crews turned their attention to permanently plugging the shallow-water well and trying to understand what went wrong, officials said.

The U.S. Coast Guard and the Bureau of Safety and Environmental Enforcement, the federal agency responsible for reviewing offshore oil and gas proposals and enforcing safety rules, said Thursday that a mixture of sand and sediment had clogged the gas well, located about 55 miles off the coast of Grand Isle.

The well had “bridged over,” they said, which restricted, then stopped, the flow of gas.

At that point, the fire decreased in intensity until the well “essentially snuffed itself out,” Jim Noe, a vice president at Hercules Offshore, which owned the rig, told the Associated Press.

Since the gas well blew out early Tuesday, many industry and environmental experts have suggested the incident is unlikely to pose major environmental consequences because the well was in relatively shallow water and released natural gas rather than heavy crude oil, much of which was likely burned off as the rig was ablaze.

The shifting sand and sediment was probably welcome news to Walter Oil & Gas Corp., the Houston oil and production company drilling the well, said Adam “Ted” Bourgoyne, a former dean of the college of engineering at Louisiana State University.

Bourgoyne anticipates that the material may have been “lifted all the way to the surface by the flowing gas, and if you get enough solids in there, they can lump together and form a plug in the tubing or the casing.”

“I don’t know that they were waiting for it,” Bourgoyne said. “They were probably praying for it would be a better explanation, and of course they were probably planning a relief well and probably planning other ways of trying to cap the well.”

The Coast Guard said the fire broke out at about 10:45 p.m. Tuesday. During a fly-over to examine the damage Wednesday, federal regulators said beams supporting the derrick and the rig floor collapsed over the rig structure amid the blaze.

By Thursday, the hull of the rig appeared to still be intact, Hercules said in a securities filing. The company has also “contracted an outside environmental expert to monitor currents, wind direction and wave height for the potential trajectory of any conceivable environmental spill,” according to a regulatory filing.

On Wednesday, Walter was moving a jack-up rig to the site with the aim of drilling a relief well, a permanent means of shutting down the well, authorities said.

The well is in about 154 feet of water. Crews were drilling the well at about 8:45 a.m. Tuesday on a platform in the South Timbalier area of the Gulf — doing completion work to prepare for production — when the well blew out. All 44 workers aboard were safely evacuated, the company said.

Hercules, the Gulf’s largest operator of jackup rigs, owned the ill-fated Hercules 256 rig, which was built in 1982. The rig was being leased to Walter on a 60-day contract, at a cost of between $101,000 and $103,000 a day, Hercules said in a May securities filing. The company had a $50 million insurance policy on the rig, and up to $110 million in wreck removal coverage, according to filings.

“From a financial standpoint, it’s not that bad,” said Luke Lemoine about the likely prospect of Hercules losing the badly-damaged rig from its fleet. Lemoine is an oilfield service analyst who follows Hercules Offshore for Capital One Southcoast in New Orleans.

For company executives and others involved in the oil and gas industry, the bigger question may lie in whether the incident poses a regulatory risk, sparked by concerns of another blowout similar in scope to 2010’s BP oil leak, he said.

“There’s no way to handicap that,” Lemoine said. In this case, “the two most important things are: no lives were lost — that’s the most important thing — and the environmental impact. It being a gas well, obviously, the environmental impact is going to be way less than if it were an oil well.”

The U.S. Chemical Safety Board, which investigates serious chemical accidents and issues safety commendations, will gather and review evidence from the rig fire, but does not plan to launch a full-scale investigation, said Daniel Horowitz, a managing director of the independent federal agency. The board is still probing the deadly chemical accident at the Williams Olefins plant in Geismar last month.

“It’s clearly a very serious incident, and it warrants study, but we are not planning to commit people to (an on-site investigation),” Horowitz said about the rig fire. “We have a full plate.”

One of the questions already being asked by experts and industry observers: What happened to the rig’s blowout preventer control system, the device designed to slice through the drill pipe in a last-ditch effort to close the well during an emergency.

The system on the Hercules 265 was approved in November 2010, records show. But the apparatus, raised above the water’s surface, apparently failed to close off the well.

Even with the gas flow stopped and the fire out, Bourgoyne said response crews still have plenty of work ahead of them. He said the well was “still plenty dangerous.” But if the plug holds, shuttering the well could be easier, he said.

“They need to come up with a plan that they can do it safely and of course weather conditions will probably have something to do with how easy it is to do it,” he added.