[Graeme]

‘Out-Of-Control’ Rig In The Gulf Gushing Methane Freely Into The Atmosphere

An “out-of-control” well that began blowing gas into the air on Thursday is still not under control as of Friday morning, according to a report from the Associated Press.

42-non essential workers from Rowan Companies PLC’s offshore rig in the Gulf of Mexico, named “Louisiana,” were evacuated, while 37 stayed on the rig to try and stop the flow of gas. Rig operator EnVen Energy Ventures said that while workers attempt to kill the well, gas was being “vented” off of the rig. Although gas, water and sand are still flowing from the well, EnVen said no pollution has occurred in the Gulf.

“All personnel currently aboard the rig are safe and non-essential personnel have been evacuated, all well control equipment is functioning as designed (and) there has been no environmental impact,” Rowan Companies spokesperson Deanna Castillo told the AP.

Unlike a spill, an out-of-control well blowing gas does not pollute in a traditional, visible sense. Instead, it releases methane — the potent, second-most prevalent greenhouse gas — into the air, contributing to climate change. Pure natural gas is mostly methane, a fuel that burns cleaner than coal or oil. However, when methane is released directly into the air, it traps heat in the atmosphere.

From an air quality perspective, it is better to burn flowing gas through a flare system, rather than venting it directly into the atmosphere, according to the Environmental Protection Agency.

It was not clear early Friday whether the companies would attempt to flare off the gas.

thinkprogress

[ROCKMAN]

Some more details:

"EnVen said in a statement that the well was put on a diverter system, as per operational protocol, to allow the formation fluids to vent overboard while work was carried out to kill the well. It added that the well continued to flow through the diverter system and efforts to kill the well were ongoing, while the BSEE noted that no visible sheen had been reported from the flowback water being sent overboard. EnVen confirmed this saying, so far, there had been no pollution from the incident as the flow was made up of natural gas, water and sand. EnVen chief operating officer Jonathan Garrett told Upstream that the well "took a kick" while drilling the well's surface hole. EnVen said the well had been drilled to a depth of 2217 feet and logging while drilling tools indicated the presence of two gas zones at 1340 and 1830 feet, as expected prior to drilling. Conductor casing had been set in the well at 1217 feet and the drill string was pulled back up to inside the casing, after which EnVen began carrying out a routine circulation when the well began to flow."

Actually blowouts from such shallow and normal pressure reservoirs is not uncommon. Very different than the much higher pressure they encountered on Macondo. I'm pretty sure I know what happened. The mud weight in the hole would have been sufficient to keep the NG from flowing up. But then they "swabbed the well in". By pulling the drill pipe out of the hole too fast they produced a partial vacuum that effectively lowered the mud weight and the gas flowed. At that shallow depth the well came blew out in seconds. They flowed the gas out of the diverter system. Usually they'll flare the gas...vented NG is one of the most dangerous situations of a rig...especially an offshore rig. Better for the environment to flare than vent. They should be able to kill the well quickly. I've been on several rigs that had to divert and flare a kick. A tad nerve racking but usually not life-threatening.

And someone may have screwed up long before the well began drilling. Early on the company had to run a sparker seismic survey designed to specifically detect "shallow drilling hazards"... like shallow gas sands like the ones that blew out. Not only does the company geophysicist look for hazards but it's required to provide the data to gov't analysts. Both safety nets appear to have failed. Not fool proof but the sparker should have seen those accumulations.