Freeze Oil

The Economist has a great article on the The Price of Staying in the Game for oil companies and their collective $1 billion effort to figure out what to do should a deepwater spill happen again.

The companies involved outlined their plan in a August 4th public meeting held by the Bureau of Ocean Energy Management. They outlined three proposals to eliminate the devastating impact of an oil spill.

Option A: Something to latch onto.
Similar to the Collar, Cap, and Collector technique used to successfully seal the Macondo well, the main component would be a containment assembly that could fit on top of a damaged blowout preventer. In the absence of a preventer, the assembly could fit on top of various other wellhead equipment or even a bare pipe through a set of adaptors and vice-like grips. This assembly would have powerful rams that could seal off the flow and could have outlets to divert that flow, if need be, into undersea piping. The outlets prevent pressure building up in a badly damaged from springing new leaks somewhere else. There were worries for some time that something like this would happen at Macondo.

Option B: Nothing to latch onto, Suction Caissons.
Sometimes there is nothing to latch on to or the oil is gushing from a hole in the seabed. For situations like this the relief response system will have a range of watertight structures called caissons. These are based on suction-pile technology use to emplace deep-sea moorings and foundations.

[MORE RESEARCH ON CAISSONS AND SUCTION-PILE TECHNOLOGY TO FOLLOW]

The suction pile is open at one end. That end is put into the sediment where the pile is to be stuck. The air is then pumped out and water pressure pushes the pile into the seabed. To make an oil-collecting caisson, such a pile would be used as a collar around a funnel-topped tube that would sit over the leak. Various sizes of caisson will be built including one 50 feet in diameter (large enough to go over the whole blowout preventer).

Once the caisson was in position with the pile pumped out and in the seabed, the caisson would fill with oil from the leak. A containment assemble attached to the top of the caisson would divert oil to a manifold (a sort of switching yard for pipe) attached to one or more floating risers to the surface. The caisson could not simply be capped because the oil pressure would blow its suction pile out of the seabed.

Option C: Capture Vessels.
The floating risers would be held vertical by buoys and direct oil from the manifold to capture vessels kitted out with special modules to flare and pump gas to adjacent tankers. The whole system could cope with a flow of 200,000 barrels a day — more than three times the 63,000 barrels a day the government estimates was the Macondo well’s peak flow rate. The capture vessels could take other jobs around the gulf, but on contracts that allowed them to break off immediately in case of emergency.

These three procedures could have capped the Macondo well within weeks. The Economist concludes with the questions: “why did such a technologically astute industry not see fit to develop such useful equipment before it was needed, rather than after? And how might that underlying and disastrous lack of foresight be corrected?”

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Interestingly, the article notes that, “Throughout the system there would be ways of warming things up and injecting antifreeze to prevent the formation of icelike methane hydrates.” I still believe the hydrates could be used as an effective solution to stopping future deepwater spills. Use of ice/hydrate forms in a caisson/suction pile could provide the expansion properties needed to block the flow and kill the spill.

National Incident Commander Thad Allen said a pressure test conducted yesterday failed to prove there is no further risk of oil leaking from the well.

As a result, BP Plc has been ordered by U.S. officials to finish the relief well it’s been drilling before the well will be declared dead.

Drilling of the relief well will resume on Sunday, with the final kill complete in about four days.

BP technicians are in final tests to determine whether to proceed with the plan to pump heavy drilling mud into the Macondo well. Tests today involved slow injections of mud into the well to make sure the pumped mud will reach the oil reservoir from the column of pipes and valves that sit on top of it. It that works out, BP will begin pumping the mud and possibly cement into the well, an operation known as static kill. Alternatively, engineers may decide to wait for a relief well to be completed before pumping cement in. There is also a chance that they will pump mud both ways, to ensure the well is fully sealed.

See the full NY Times article here.

And more here:

While the static kill may only plug the center well pipe, the relief well will penetrate both the central pipe and the portion of the well between the inner piping and the outer casing. That area — called the annulus, and akin to the space between a straw inserted in a tumbler of water and the glass itself — probably will not be reached by the mud and cement injected by the static kill.

Efforts to permanently plug the gusher hit a snag when crews found debris in the bottom of the relief well that need to be fished out before crews can pump mud into BP’s busted well in a procedure known as a static kill.

The sediment settled in the relief well last week when crews popped in a plug to keep it safe ahead of Tropical Storm Bonnie. They found it as they were preparing for the static kill and now they have to remove it. They had hoped to start the static kill as early as Sunday, but removing the debris will take 24 to 36 hours and like push the kill back to Tuesday.

“It’s not a huge problem, but it has to be removed before we can put the pipe casing down,” retired Coast Guard Adm. Thad Allen, the government’s point man for the spill, said Friday.

After the static kill comes the bottom kill, where the relief well will be used to pump in mud and cement from the bottom of the busted well and hopefully cut off the oil permanently.