BP’s name may be mud in environmental circles, but that’s also its latest tactic in the plan to permanently end the biggest accidental oil spill in history.
The company is today beginning efforts to stem the flow of oil, which has so far released the equivalent of 4.9 million barrels of liquid, through a technique which, in concept at least, is remarkably simple.
To date BP has tried several measures to control the situation, all appearing somewhat primitive. Then again, it’s arguable that it’s the scale of the spill that’s causing the complexity rather than the task of plugging the leak itself.
One major tactic to stop the leak (rather than merely control what happened to the oil) was the “junk shot”. The company fired debris such as golf balls and shredded car tires into the well at high pressure in an attempt to clog up the exit. That was considered a longshot, and proved unsuccessful.
Another technique was the use of a cofferdam: a giant dome lowered over the leak to try to keep it under control. That failed to work because of a build up of crystallized gas.
Now the phrases being bandied about are the “top kill”, “static kill” and “bottom kill”. The top and bottom simply refer to where in the well the stemming is attempted.
Explained simply, the static top kill, which the company is attempting this week, is simply a variant on the junk shot, using mud and possible concrete to try to clog up the well.
Art Berman, a geological consultant, writes at the Oil Drum website that the technique isn’t quite as simple as has been described. Contrary to some reports, the mud won’t be continuously pumped into the well until the oil is pushed back. Instead it will be done in stages, with each set of mud sinking to the bottom of the well before some of the oil is allowed to go back up to the surface to reduce the pressure.
Bertman also notes that a bottom kill would be safer as there would be less pressure at the head of the well and thus less risk of rupturing the casing. But he explains that time constraints mean the top kill is the better option, as long as those involved realize they may have to put the kibosh on the scheme if the danger of a rupture begins to emerge.
If the static top kill doesn’t do the trick, there may be no option other than to fall back on the ongoing work to build two extra wells to ease the pressure on the ruptured well and remove the oil in a more controlled fashion.