No one seems to know how much oil is spewing into the Gulf of Mexico from the Deep Sea Horizon disaster. BP, for whom the well was being drilled 5000 feet below sea level in the Mississippi canyon of the Gulf of Mexico, initially estimated the leak rate to be 1,000 barrels a day (42,000 gallons). They later raised the estimate to 5,000 barrels (210,000 gallons). More recently BP has accepted U.S. government estimates of a rate between 12,000 and 19,000 barrels a day. The latest estimate, 800,000 gallons using the 19,000 barrel upper limit, is apparently based on measurements of surface area of visible oil slicks.
Other estimates are higher. In the following section, a scientific estimate of 3.4 million gallons a day, more than four times the government estimate, is quoted. Yesterday, Toby Harnden and Richard Alleyne, in The Telegraph reported the largest estimate as 4 million gallons a day.
You Can't Tell a Book by its Cover
There is apparently a big problem with the official estimates. Scientists are finding that there is a lot of oil in addition to that visible on the surface. Justin Gillis, in the May 15 issue of The New York Times, wrote:
Scientists are finding enormous oil plumes in the deep waters of the Gulf of Mexico, including one as large as 10 miles long, 3 miles wide and 300 feet thick in spots. The discovery is fresh evidence that the leak from the broken undersea well could be substantially worse than estimates that the government and BP have given.
The plumes could contain much more oil than seen on the surface. Plumes have been measured as deep as 4,200 feet. The exact composition is not known but they are most likely suspended droplets of oil in water, possibly the consistency of salad dressing. The volume of the large plume described in the quote above (10 miles x 3 miles x 300 feet thick) would be nearly 7 trillion gallons. Obviously, the amount of oil suspended in such a volume would be much less than the amount of oil released to date, which would be no more than 136 million gallons based on the estimate quoted below. If this one plume contained 1% of the amount released to date (it probably contains much less), then the fraction of the plume which is actually oil would be about 0.00002%. According to the May 15 NYT article:
Scientists studying video of the gushing oil well have tentatively calculated that it could be flowing at a rate of 25,000 to 80,000 barrels of oil a day. The latter figure would be 3.4 million gallons a day. But the government, working from satellite images of the ocean surface, has calculated a flow rate of only 5,000 barrels a day.
Scientists from the University of Georgia, University of South Florida, University of Mississippi and Southern Mississippi have been involved in the effort. BP has denied scientists’ requests to put additional equipment on the ocean floor at the well head to get more accurate measurements.
Scientists have measured oxygen depletion in the vicinity of plumes. This is a worry because oxygen depletion could damage marine life. Dispersed oil can be attacked by bacteria that decompose the oil into carbon dioxide and water. This solution can also cause a problem because the bacteria use dissolved oxygen in the surrounding water in the decomposition process. Lack of oxygen can produce dead zones in the sea and the rate of reintroduction of oxygen at ocean depths can be very slow.
How Could the Plumes be Created?
The violent eruption of oil into the deep ocean could produce dispersion, much like the shaking of oil and vinegar makes a salad dressing. However, it is likely that some the dispersed oil results from the chemical dispersants that BP has been using near the discharge point to prevent the build up of large “flotillas” of oil. This effort is aimed at reducing the impact of oil on the shores of the gulf. But what are the consequences to the larger marine environment? I don’t think we know yet. Could the unintended consequence of diminishing the impact on the shore be the killing of the sea?
The Plumes are Moving
Another Justin Gillis article in The New York Times last Friday, May 28, reported that locations where plumes were found in early May had none now, but plumes were discovered in other places. The original plumes were found southwest of the blown out well. The most recent samplings have found plumes northeast of the site, in the direction of the fertile fishing grounds near Mobile, Alabama. Oxygen depletion in those fishing grounds could be catastrophic.
The testing is far from exhaustive, with vast areas of the gulf not sampled. The fact that the limited sampling has found so many plumes implies that many more remain to be discovered.
BP Says It’s All Hokum
BP CEO Tony Haywardsaid Sunday night that there are no oil plumes. From an Associated Press release by Matthew Brown:
Disputing scientists' claims of large oil plumes suspended underwater in the Gulf of Mexico, BP PLC's chief executive on Sunday said the company has largely narrowed the focus of its cleanup to surface slicks rolling into Louisiana's coastal marshes.
During a tour of a BP PLC staging area for cleanup workers, CEO Tony Hayward said the company's sampling showed "no evidence" that oil was suspended in large masses beneath the surface. He didn't elaborate on how the testing was done.
Hayward said that oil's natural tendency is to rise to the surface, and any oil found underwater was in the process of working its way up.
"The oil is on the surface," Hayward said. "There aren't any plumes."
Historical Comparisons
Toby Harnden and Richard Alleyne (The Telegraph) compare the extent of the Deep Sea Horizon disaster to other historical spill events. Using the 4 million gallon a day figure, they say that, if the leak continues for an additional 90 days the disaster would lead to 378 million gallons polluting the Gulf of Mexico.
I can’t duplicate the calculation. If the 40 days already passed are increased by another 90 days, 130 days in total, I get 520 million gallons total. The total for 90 additional days alone would be 360 million gallons, close to the 378 million gallons Harnden and Alleyne specify.
Since the next attempt to stop or reduce the flow will involve a risk of increasing the oil flow by 20% or 30% if unsuccessful, the current flow rate estimates could be increased in the future. However, we don’t know that we aren’t too high with the most aggressive flow estimates, so anticipating a higher flow is not considered productive at this point.
The largest oil spill comparisons given by Harndem and Alleyne are:
· 520 million gallons in the Persian Gulf in 1991.
· 140 million gallons in the Gulf of Mexico (Ixtoc oil well) on 1979-80.
· 11 million gallons from the Exxon (XOM) Valdez spill in Alaska in 1989.
Using the government daily volume estimate (800,000 gallons a day) for 110 days would give an 88 million gallon spill. The term of 110 days is selected because that takes us to the end of the first week in August, the earliest anticipated date for completion of the first relief well.
The same end date and using the 4 million gallon a day estimate produces a spill total of 440 million gallons.
Comparisons are Premature, but Costs can be Estimated
There is no basis at this point for making comparisons. If we use the latest government accepted estimates, 800,000 gallons per day for 40 days puts the total to date at 32 million gallons, almost 3x the Exxon Valdez spill. Other research estimates are much higher. Exxon Mobil has spent in excess of $3 billion to settle litigation and conduct clean up activities. I understand one can still turn over shoreline rocks and find residual oil today, so the clean up can not be considered exhaustive.
It may be that the clean up in marsh lands and dispersions in open water may be more expense. It is certainly true that the much larger affected population could expose BP to much greater litigation liability. The cost to BP for this event is likely to be more per gallon. For the XOM, the cost was of the order of $270 + per gallon. Using that figure, the prospects for BP are close to $9 billion if the oil stops today and the government volume estimates are valid. With the same miraculous end of flow today, the higher scientists estimated rate would result in a liability greater than $40 billion.
If the well continues to flow until August, the costs to BP could exceed $25 billion (government flow estimates) and over $100 billion (scientists’ flow estimates).
For reference, BP recorded net earnings of $21 billion per year for 2006, 2007 and 2008.
Disclosure: No positions.
