What does the setback with the diamond saw mean for BP’s efforts to contain the oil flow in the Gulf of Mexico?
The saw was meant to make a clean cut across the top of the riser — a large pipe leading out of the blow-out preventer — that would enable a containment cap to be tightly fitted, capturing the oil and funneling it back up to the surface.
However it got stuck halfway through. The diamond saw has now been freed and BP CNN is reporting that Admiral Thad Allen, incident commander, says BP has ‘abandoned’ use of the diamond saw, and will instead use the giant shears (see image), which successfully severed the lower part of the riser, to make another cut above the blow-out preventer.
The shears are large and not especially precise, as the video below of the shears’ successful earlier cut demonstrates:
The implications of this are big: the shears cannot make as precise a cut as the diamond saw, which would make it more difficult to get a ‘seal’ on the leak and trap all the oil.
So the big question appears to be whether, without the precision of the diamond saw, a clean enough cut can be made to tightly fit the LMRP cap, without letting too much oil leak out. (Check out BP’s technical video to understand what they were trying to do, and a new Oil Drum post which looks at what actually happened).
The setback with the blade may lead to a looser fit and a higher rate of oil leakage between the blowout preventer and cap, Allen said today at a press conference in Houma, Louisiana. BP, based in London, will decide today whether a coarser blade is required, he said.
We should note that BP itself has not ruled out either the diamond saw or sealing it to the LMRP as planned, its GoM response page merely says preparations are under way to cut the riser — without specifying which device, or what comes next. CNN claims that the option of sealing up the cap is off the table, along with the diamond saw, and instead the company is planning to use the ‘top hat’ that it had considered a couple of weeks ago.