by Tenebris

Created on: May 18, 2010

To contain an offshore oil leak, its source must be known. If the leak is directly from the wellhead, it must be capped or otherwise closed off as soon as possible. If it is from the riser, as in the 2010 Deepwater Horizon drilling rig disaster, the riser must be repaired or sealed off below the leak. A new, slant-drilled well which taps into the same reservoir can be used to pump in seawater and concrete to plug the well. Only after the submarine leak is capped can the surface oil slick be properly dealt with. If, however, the blowout preventer cannot seal the leak, further technology for stopping offshore deepsea oil leaks at the source remains extremely experimental.

Emergency oil diversion

The blowout preventer

A fully functional blowout preventer should automatically seal off the wellhead. In case of sudden pressure change, blowout preventers are supposed to seal off or even shear right through the annulus, preventing methane bubbles and other formation fluid from rising any further. The 2010 Deepwater Horizon drilling rig disaster was caused in part by a blowout preventer failure. Had it functioned properly, the explosion should not have happened in the first place, since either the crew or a dead-man’s switch should have severed the drill string at the first sign of a methane bubble.

Where the leak is due solely to a malfunctioning blowout preventer, it could potentially be stopped by sending remotely controlled submarine robots to the sea floor to fix it. This approach is handicapped, however, by uncertainty over whether any readings are accurate to physical reality. Even if the robots do succeed in deploying BOP valves, subsequent damage from the explosion and rig collapse may render those valves useless.

Subsea oil recovery system

If a pollution dome can be successfully placed around the source of the leak, leaking oil can be restricted to a limited area. The oil-water mixture can then be pumped up to the surface through a new pipeline without contaminating the rest of the water. At the surface, the oil can be separated from the water and any natural gas; and then sent off to be refined more or less normally. The Deepwater Enterprise, the processing ship brought in to deal with the Deepwater disaster, is capable of processing up to 15,000 barrels of oil per day. This system could potentially divert as much as 85% of all leaking oil - but it has only previously been used in shallow water less than 100 metres deep. It has never been

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