The goverment’s official estimates of how much oil is gushing out of the BP well rose dramatically Tuesday, to between 35,000 and 60,000 barrels/day. The official explanation for that dramatic rise implies the change was primarily a result of better measurements.
But oil drilling experts are saying it’s plausible the flows rushing up the well are in fact increasing because the opening is eroding and thus expanding. That suggests to me that the Administration’s directives to BP that it substantially increase its capture and recovery capabilities may eventually be overtaken as the flows increase.
First, via Huffington Post’s Sam Stein, a quote from the White House experts’ report on their new measurements:
Working together, U.S. government and independent scientists estimate that the most likely flow rate of oil today is between 35,000 and 60,000 barrels per day. The improved estimate is based on more and better data that is now available and that helps increase the scientific confidence in the accuracy of the estimate. . . .
The Lower Marine Riser Package (LMRP) cap that is currently in place can capture up to 18,000 barrels of oil per day. At the direction of the federal government, BP is deploying today a second containment option, called the Q4000, which could expand total leak containment capacity to 20,000-28,000 barrels per day. Overall, the leak containment strategy that BP was required to develop projects containment capacity expanding to 40,000-53,000 barrels per day by the end of June and 60,000-80,000 barrels per day by mid-July.
"This estimate brings together several scientific methodologies and the latest information from the sea floor, and represents a significant step forward in our effort to put a number on the oil that is escaping from BP’s well," said Energy Secretary Steven Chu. "As we continue to collect additional data and refine these estimates, it is important to realize that the numbers can change. In particular, the upper number is less certain – which is exactly why we have been planning for the worst case scenario at every stage and why we are continuing to focus on responding to the upper end of the estimate, plus additional contingencies."
You get the sense the reason this lastest estimate is dramatically higher is only because we’re now making better measurements than before. The argument that cutting the riser increased the flows much more than expected is not used. But there’s no suggestion the underlying potential has worsened because of deteriorating conditions.
Over at The Oil Drum, however, they’ve been discussing the natural processes by which oil and gas under high pressure, plus sand, gradually erode the integrity of the protective restrictions from the bottom of the well and the damaged openings in the blowout preventer. The cutting effects of sand blasting into and up the well gradually enlarges the openings, including through the BOP where BP is trying to capture the gushing oil and gas. From The Oil Drum (my bold):
The pressures across the BOP don’t show the pressure drops that they did earlier in this disaster. At one time it was reported that the pressure below the BOP was in the 8-9,000 psi range and that above it 2,800 psi with the 2,250 psi pressure being that of the seawater outside the riser. At that time I calculated that a flow of 500 gallons per minute (17,000 bd) would only require a gap in the range of 0.5 to 0.7 inches in effective diameter to allow that flow, at that pressure drop.
The pressure below the BOP is now at 4,400 psi with a pressure drop of around 2,150 psi which will slow the erosion significantly – but not totally. For that pressure drop to have occurred, for the same flow rate, the effective equivalent diameter through the BOP need only increase by 0.1 inches to 0.8 inches, which is not a lot. Were the effective diameter to increase by only another 0.15 inches the flow would increase to 25,000 bd, and if the effective diameter were to double to about 1.7 inches, then the flow would reach the maximum capacity that BP will be able to handle of 80,000 bd. Given the steady erosion that the BOP is seeing, and the fact that a slow erosion rate over time still gets to a large enough diameter, perhaps it is not foolish of BP to bring in that additional capture and storage capacity.
The experienced folks there have been invaluable, and they’re not prone to hyperbole. But I don’t see any reason to assume that the blasting erosion that could lead to 80,000 bbls/day is the end of the story. Why not beyond that?
So what we may be witnessing is a terrifying race against time, in which BP will continually be unable to keep up with a gusher expanding faster than they can assemble capture and recovery techniques. Instead of making progress by capturing more, matters could be getting worse and will keep getting worse unless/until they seal this from the bottom, it that’s still plausible.