BP's Oil Disaster: The Dangers and Difficulties of 'Bottom Kill'

(Image: Der Spiegel, " How 'bottom kill' works.")

Der Spiegel
By Philip Bethge

"BP has only one arrow left in its quiver, a method known as 'bottom kill.' The idea is for relief wells to stop the gushing oil from below, but the technical challenges are formidable. Past experiences show that the oil may continue flowing into late autumn."...

..."BP's most recent efforts to stop the flow of oil have only made the situation worse, says Leifer. The engineers' attempt to seal off the well from above, using a method known as "top kill," failed and only enlarged the borehole, according to Leifer. Now, he adds, there is almost nothing stopping the oil from flowing out of the well.

Most experts now believe that the relief wells, despite the risks, are the only option left. The principle of the method sounds simple enough. The engineers start by drilling vertically, and then diagonally toward the out-of-control well. Once they've reached the well, they drill into it from the side and pump large amounts of mud into it. The material fills up the well from below and eventually acts as a plug. In the end the well, like a decayed tooth, is capped with cement.

As straightforward as it sounds, this approach has not always been easy to implement in the past. The disaster in the Timor Sea, for example, ended in a debacle. It took engineer five tries to even find the borehole under the sea floor. Shortly before the end, the West Atlas oilrig went up in flames, after all." More>>>>