Update: "Portions of the Hercules drilling rig that is on fire in the Gulf of Mexico started to collapse Wednesday.

The parts of the Hercules 265 rig that stick out over the Walter Oil & Gas platform and wellhead have been melting and falling, but the integrity of the massive post-like legs and the permanent platform itself appear to still be strong, Walter Oil & Gas spokesman Brian Kennedy said.

Walter is hiring a jack-up rig to start drilling a relief well at the site. The jack-up rig will be towed in next to the Hercules drilling rig, where it will start drilling a relief well into the Gulf of Mexico to intercept Hercules' well.

The federal offshore safety agency reported that beams supporting the derrick and rig floor on the Hercules have folded and collapsed."
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Federal officials say fire has broken out on an out-of-control natural gas well in the Gulf of Mexico well just hours after it was evacuated on Tuesday.

WSJ:

"Natural gas continued to leak from the well Tuesday afternoon, creating a cloud around the rig and film on the water, but it was dissipating quickly, according to the Bureau of Safety and Environmental Enforcement.

Walter Oil & Gas Corp., the owner of the well, cited a problem with safety gear known as a blowout preventer, but later said it is still investigating the incident and wouldn't know the cause of the blowout, or why the well continues to flow, for some time.

A blowout preventer is a set of valves that are meant to close down a well in an emergency to stop the flow of oil and gas; in this case, the equipment was located on board the rig.

The failure of a blowout preventer far below the sea was implicated in the 2010 Deepwater Horizon explosion, which killed 11 workers and led to the biggest offshore oil spill in U.S. history.

Tuesday's incident came after workers lost control of another well earlier this month in the shallow waters of the Gulf, where workers were in the process of plugging an aging well owned by Talos Energy LLC. That well leaked a small amount of gas and light condensate before it was plugged."

From the Associated Press:

"No injuries were reported as a result of the fire, Eileen Angelico, a spokeswoman for the Bureau of Safety and Environmental Enforcement, told The Associated Press.

She said it wasn't known what caused the gas to ignite. It also wasn't clear early Wednesday how and when crews would attempt to extinguish the blaze. BSEE said earlier Tuesday that a firefighting vessel with water and foam capabilities had been dispatched to the scene.

Wild Well Control Inc. was hired to try to bring the well under control. Angelico said Wild Well personnel approached the well earlier Tuesday night, before the fire, but they determined it was unsafe to get closer when they were about 200 feet away from it."

Officials have stressed that Tuesday's blowout wouldn't be nearly as damaging as the BP oil spill of 2010, although natural gas released into open water can have hazardous consequences.

Via:

"Especially dramatic situations developed in the Sea of Asov as a result of two large accidents on drilling rigs in the summer-autumn of 1982 and 1985. These accidents caused long-term releases of large amounts of natural gas into the water accompanied by self-inflaming of the gas. During these events, the levels of methane in surface waters exceeded the background concentrations up to 10-100 times. The air samples also showed very high concentrations of methane. These accidents drastically disturbed the composition and biomass of the water fauna and caused mass mortality of many organisms, including fish and benthic mollusks."

Another component of natural gas - hydrogen sulfide - is water soluble in contrast with methane. It can cause hazardous pollution situations in both the atmosphere and the water environment:

"Pollution by hydrogen sulfide can lead to disturbances in the chemical composition of surface waters. This gas belongs to the group of poisons with acute effects. Its appearance in the atmosphere and hydrosphere can cause serious economic damage and medical problems among local population."

Updates on this situation as information becomes available.