Late yesterday, BP halted its effort to capture the torrent of oil flowing from the wrecked riser of its ocean floor blowout well due to hydrates that clogged the containment vessel. Hydrates (in this case) are crystals that are often formed when methane hits water under the right conditions. It is a common problem in offshore risers and pipelines. As oil and gas flow from the blowout well and hits the seawater, water molecules essentially trap methane molecules without chemically bonding. This trapping of methane forms crystals that can build very quickly, slowing flow, and sometimes completely blocking lines. In this case, the hydrates built so quickly that the containment vessel, a large concrete and steel box attached to a riser that was designed to capture the majority of oil escaping from the uncontrolled well, was indeed clogged.
BP threw in the towel, at least until they figure out what to do, and lifted the vessel from off of the leaking riser and set it aside. Hydrates are most often treated by injecting methanol or chemical inhibitors into the well stream, and sometimes by applying heat. At this depth and temperature, I would think that heat is pretty challenging, so it seems that inhibitors would be the best plan. I also believe that BP anticipated this, and have a method of injecting the inhibitor, but were surprised that it happened so fast. The critical factor here, I believe, is getting the system "closed" where only the oil, gas, and produced water is in the vessel and riser. They can then control hydrate formation with an inhibitor or other treatment.
The speed in which the vessel clogged is yet another indicator to me that the flow of the well could be much higher than the reported 5,000 barrels per day. The vessel, if my calcs are correct, holds about 2,400 barrels of liquid. Assuming that it settled into the sea floor down to the "mud flaps" welded to the sides, that would cut capacity to about 1,200 barrels. At 5,000 barrels per day flow, the vessel would fill in about 6 hours. At 25,000 barrels per day, it would fill in just over an hour. The velocity through the connection would be very high, setting up perfect conditions for rapid hydrate formation, which is exactly what happened.
As this environmental and technological disaster continues to unfold, it is becoming very clear that our technology to drill in these inhospitable locations has outstripped our ability to cope with the problems when something goes terribly wrong. I have convinced myself that it's time to step back from deepwater development with subsea facilities until we come up with a reliable way to keep these kinds of disasters from not only happening; but more importantly, knowing how to quickly cope with them when they do.