Methane-Trapping Ice May Have Triggered Gulf Spill

sciencehabit writes with an excerpt from Science that begins: "Methane-trapping ice of the kind that has frustrated the first attempt to contain oil gushing offshore of Louisiana may have been a root cause of the blowout that started the spill in the first place, according to [UC Berkeley] professor Robert Bea, who has extensive access to BP p.l.c. documents on the incident. If methane hydrates are eventually implicated, the US oil and gas industry would have to tread even more lightly as it pushes farther and farther offshore in search of energy."

Comments

Re:Arctic?

[LehiNephi]

Hydrates require both high pressure and low temperature to form, along with the proper composition of water and methane. Take away any of the three, and hydrates disappear. Typically the gas/water/oil is warm enough when it reaches the surface that hydrates do not form, and by the time it cools down enough, it has already been processed so that the water and methane are no longer mixed.

Re:Spill baby spill!

[Shakrai]

One liter of water ice that has trapped individual methane molecules in the "cages" of its crystal structure can release 168 liters of methane gas when the ice decomposes."

I wonder if that can be harnessed as an energy source?

Re:Spill baby spill!

[budgenator]

"This well had been giving some problems all the way down and was a big discovery. Big pressure, *16ppg+ mud weight*. They ran a long string of 7" production casing - not a liner, the confusion arising from the fact that all casing strings on a floating rig are run on drill pipe and hung off on the wellhead on the sea floor, like a "liner". They cemented this casing with lightweight cement containing nitrogen because they were having lost circulation in between the well kicking all the way down. The calculations and the execution of this kind of a cement job are complex, in order that you neither let the well flow from too little hydrostatic pressure nor break it down and lose the fluid and cement from too much hydrostatic. But you gotta believe BP had 8 or 10 of their best double and triple checking everything. On the outside of the top joint of casing is a seal assembly - "packoff" - that sets inside the subsea wellhead and seals. This was set and tested to 10,000 psi, OK. This was the end of the well until testing was to begin at a later time, so a temporary "bridge plug" was run in on drill pipe to set somewhere near the top of the well below 5,000 ft. This is the second barrier, you always have to have 2, and the casing was the first one. It is not know if this was actually set or not. At the same time they took the 16+ ppg mud out of the riser and replaced it with sea water so that they could pull the riser, lay it down, and move off. When they did this, they of course took away hydrostatic on the well. But this was OK, normal, since the well was plugged both on the inside with the casing and on the outside with the tested packoff. But something turned loose all of a
sudden, and the conventional wisdom would be the packoff on the outside of the casing. Gas and oil rushed up the riser; there was little wind, and a gas cloud got all over the rig. When the main inductions of the engines got a whiff, they ran away and exploded. Blew them right off the rig. This set everything on fire. A similar explosion in the mud pit / mud pump room blew the mud pumps overboard. Another in the mud sack storage room, sited most unfortunately right next to the living quarters, took out all the interior walls where everyone was hanging out having - I am not making this up - a party to celebrate 7 years of accident free work on this rig. 7 BP bigwigs were there visiting from town. In this sense they were lucky that the only ones lost were the 9 rig crew on the rig floor and 2 mud engineers down on the pits." TRANSOCEAN DEEPWATER HORIZON EXPLOSION-A DISCUSSION OF WHAT ACTUALLY HAPPENED? Reply by Garry Denke on May 4, 2010 at 6:06pm

The "kicks" he's talking about are pressure surges from gas in the well, so everybody knew what the well was doing because it was kicking all the way down, so no surprises there. The well was drilled, Halliburton was contracted to cement the casing which was done and tested and they were pumping out the mud from the riser pipe and filling it with seawater when the explosion occurred. The riser pipes is rated for 15,000 PSI and have a 3.5 million pound load-carrying capacity, between these riser pipes and the blowout preventer is a connector device rated for 7 million foot-pounds of bending load capacity. Right now this riser pipe comes out of the well head goes up 1500 feet and is bent over and the free end is now buried in the seabed. I don't see where they were cutting costs too much. Deepwater Horizon would probably have disconnected from the well and moved on in a day or two if there hadn't been an explosion.