The second of BP’s spill containment domes was deployed yesterday in another to attempt to cap off the main oil leak in the Gulf of Mexico. However, the action is not yet completed, and there will still be tense moments in the hook-up phase yet to come. The dome has reached the seafloor and is expected to be activated by Monday.
BP’s first cofferdam attempt encountered at setback as the 98 ton dome was lowered over the gushing oil on the seabed. Some 5,000 feet down, it was found that ice crystal hydrates formed from the gas and water mixing at high pressure and very low temperatures clogged up the top of the dome. Although it is possible to melt these large crystals, there is a problem in keeping the dome clear enough to put in a line to pump up the oil to a ship on the surface.
This second dome, the ‘Top Hat’, attempts to avoid the problem by keeping the pipe that is linking it to the drill ship warmer than the surrounding seas, by having a riser ‘overcoat’ that will be heated by hot water and methane. Also, it is much smaller than the original dome, with less volume of water inside to cause problems.
BP is also doing further work on options aimed at stopping the flow of oil from the well. This includes a possible ‘junk shot’ of rubber and other materials into the failed blowout preventer of the well to try to plug it. This option is actively being pursued in parallel with other devices to contain the spill over the next two weeks.
However, BP admits that all of the techniques involve significant uncertainties. One problem BP’s engineers are keen to avoid is the possibility that the junk shot could further rupture the leaking pipe, causing even more than the present 210,000 gallons a day being added to the spill.
A more distant long term solution is a relief well, which is presently underway, but which will take at least until mid-July to complete.