Oobleck Top Kill

Last May, when BP was trying to stop the flow of oil out of the Macondo well in the Gulf of Mexico, they used top kill, a heavy mud pumped into the well to suppress the upward gushing. The procedure failed and the oil continued to flow until July when the well was finally capped.

If only BP had consulted a few preschoolers first, they may have been more successful.

Last week, physicists published a paper in Physical Review Letters on the power of oobleck, that magic mixture of two-parts cornstarch and one-part water often found surrounding the grubby hands of toddlers.

Scientists were skeptical of the top kill method to begin with, even though BP thought it would be 60-70% successful. At the time, Jonathan Katz, PhD, of Washington University, suggested a simple fix, changing the mud recipe to the cornstarch and water oobleck mixture. His reasoning:

It can flow slowly as a liquid, but turns stiff and elastic when flow is rapid. If an instability were to occur, this stiffness would suppress it, and it would sink in the well, accumulating at the bottom until its pressure became sufficient to stop the leak.

But the top kill mud had worked previously, during the first Gulf War, and Katz’s suggestion was ignored.

Despite the brush-off, and perhaps because of the top kill failure, Katz worked with Lawrence Livermore National Laboratory researchers in testing his theory in the lab:

We poured cornstarch ‘mud’ into the top of the oil column and observed that, as predicted, the instability was suppressed. The surrogate ’mud’ sank rapidly through the oil to the bottom of the tube.

Based on this experiment, the addition of a shear-thickening polymer like cornstarch to a dense top-kill mud might have allowed slugs of mud to descend against the upwelling oil instead of being ripped up and spat out of the well. Eventually, the column of mud would have prevented any further infiltration from the oil reservoir, killing the well.

Katz hopes there will never be an opportunity to repeat the experiment at full scale and under field conditions, but if there is, perhaps his advice will reach beyond the ears of preschoolers.

Image by eyspahn/flickr