A decade-old environmental assessment by offshore drilling regulators called for more research on Corexit dispersant, warned that deepwater spills were difficult to stop, and cautioned that such spills could "permanently cover water bottoms and wetlands."
At the same time, it cited industry speculation that a deepwater blowout could stop itself in a matter of days and concluded that deepwater spills were "a very low-probability event."
The document, written in 2000, was mentioned in Sunday's New York Times story about the Minerals Management Service and its record of drilling oversight. The Times called the environmental assessment a "document at war with itself" that reflects the regulatory agency’s conflicting mandates: facilitating energy production and royalty collection while ensuring that offshore drilling is done safely, with proper environmental consideration and review.
From one part of the document, highlighting the risks:
Although the loss of well control (blowout) is not a new source of spills, the likelihood and magnitude of spills from them or from a large pipeline rupture in deep water may be very different from the likelihood and magnitude of such spills in shallow water. Of particular concern is the ability to stop a deepwater subsea spill once it begins, thus limiting its size. For a subsea blowout, the lack of a surface structure and the possible high-flow rate that may be encountered may make intervention to regain control of a subsea well difficult.
From another part of the document, downplaying the risks:
The oil and gas industry has speculated that because the deepwater sediments are relatively unconsolidated, a deepwater blowout may stop flowing in several days to a few weeks as failure of a portion of the bore hole, called bridging over, blocks the flow.
The document also probed some of the questions that—10 years and 200 million gallons of spilled crude later—we still don’t know have answers to. "Virtually nothing is known" and studies are "completely lacking" about the effect of dispersants on marine mammals and sea turtles, the document says. In a section called "suggested research," the document also raised questions about whether Corexit was the best dispersant choice:
In addition, development of a better understanding of the dispersability of deepwater crudes would support the determination of whether or not the dispersant (Corexit 9527) at present stockpiled in the Gulf of Mexico is the best choice for dispersing these oils.
And though the government has already announced that most of BP’s spilled oil is already gone from the Gulf, the document also addresses potential long-term effects, pointing out that some elements of the oil could linger permanently:
Deepwater-produced oils may contain high asphaltene concentrations. Spills of such oils may permanently cover water bottoms and wetlands, increasing the occurrence and volume of tar in the marine and coastal environments.
Asphalt is the heaviest part of an oil molecule, according to National Geographic, which pointed out in a piece over the weekend that despite all the hype—or in the words of one researcher, "total bull"—about oil-eating microbes getting rid of the oil, the microbes "can’t stomach asphalt."