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Why Is It So Hard to Stop the Oil Gusher, and Why Was Such Extreme Deepwater Drilling Allowed in the First Place?
The government failed to properly ensure that BP used adequate safety measures, BP and their contractors were criminally negligent for the oil spill, and BP has tried to cover up the problem.
But why hasn’t BP stopped the leak?
Some people assume that BP hasn’t stopped the oil leak because it’s people are wholly incompetent.
Others have asked whether BP’s $75 million liability capis motivating it to stall by taking half-hearted measures until it’s relief well drilling is complete.But there is another possible explanation: the geology – as well the deepwater pressures – at the drilling site makes stopping the leak more difficult than we realize.
Does the Geology of the Spill Zone Make It Harder to Stop the Oil Spill?
We can’t understand the big picture behind the Gulf oil spill unless we know the underwater geology of the seabed and the underlying rocks.
For example, if there is solid rock beneath the leaking pipes, with channels leading to various underground chambers, then it might be possible to seal the leaking risers and blowout preventer, with the oil flowing somewhere harmless under the floor of the ocean.
On the other hand, if there are hundreds of feet of sand or mud beneath the leaking pipes, then sealing the spill zone might not work, as the high-pressure oil flow (more than 2,000 pounds per square inch) might just shoot out into the water somewhere else.
We don’t know the geology under the spill site. BP has never publicly released geological cross-sections of the seabed and underlying rock. BP’s Initial Exploration Plan refers to "structure contour maps" and "geological cross sections", but all detailed geological information, maps and drawings have been designated "proprietary information" by BP, and have been kept under wraps.
However, Roger Anderson and Albert Boulanger of Columbia University’s Lamont-Doherty Earth Observatory describe the basic geology of the oil-rich region of the Gulf:
Production in the deepwater province is centered in turbidite sands recently deposited from the Mississippi delta. Even more prolific rates have been recorded in the carbonates of Mexico, with the Golden Lane and Campeche reporting 100,000 barrel per day production from single wells. However, most of the deep and ultra-deepwater Gulf of Mexico is covered by the Sigsbee salt sheet that forms a large, near-surface “moonscape” culminating at the edge of the continental slope in an 800 meter high escarpment.
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Salt is the dominant structural element of the ultra-deepwater Gulf of Mexico petroleum system. Large horizontal salt sheets, driven by the huge Plio-Pleistocene to Oligocene sediment dump of the Mississippi, Rio Grande and other Gulf Coast Rivers, dominate the slope to the Sigsbee escarpment. Salt movement is recorded by large, stepped, counter-regional growth faults and down-to-the-basin fault systems soling into evacuated salt surfaces. Horizontal velocities of salt movement to the south are in the several cm/year range, making this supposedly passive margin as tectonically active as most plate boundaries.
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Porosities over 30 percent and permeabilities greater than one darcy in deepwater turbidite reservoirs have been commonly cited. Compaction and diagenesis of deepwater reservoir sands are minimal because of relatively recent and rapid sedimentation. Sands at almost 20,000 feet in the auger field (Garden Banks 426) still retain a porosity of 26% and a permeability of almost 350mdarcies. Pliocene and Pleistocene turbidite sands in the Green Canyon 205 field have reported porosities ranging from 28 to 32% with permeabilities between 400 mdarcies and 3 darcies. Connectivity in sheet sands and amalgamated sheet and channel sands is high for deepwater turbidite reservoirs and recovery efficiencies are in the 40-60% range.
The BP oil spill leak is occurring in Block 252 of the "Macondo" Prospect in the Mississippi Canyon Area of the Gulf. The Mississippi Canyon Area is very typical of the Gulf oil region.
If the geology at Block 252 is like that described by Anderson and Boulanger for the Gulf oil region as a whole, then it might be difficult to stop the oil gusher without completing relief wells (which will take a couple of months). Again, if there are salt layers right under the sea floor, high porosity near the surface or salt movement, then sealing the leak by plugging the risers and blowout preventer might not work. The oil pressure is coming up at such high pressures that sealing the leaking equipment at the level of the seabed might just mean the oil will flow out somewhere else nearby.
The government must publicly release details of the geology under the spill site. The American people – and people in Mexico, Cuba and other countries which might be affected by the spill – have a right to know what we’re dealing with.
Until it does so, people will not have be understand what is going on. And failing to release such information may prevent creative scientists from around the world from coming up with a workable solution.
Moreover, as the first draft of Anderson and Boulanger’s paper – released in 2001 – noted:
No means currently exists to produce oil and gas to market from such water depths!
(exclamation point is Anderson and Boulanger’s). In other words, the technology to drill in such deepwater conditions in the Gulf has only been developed after 2001.
While BP, its subcontractors, and the government were all negligent with regard to the Deepwater Horizon operation, it must be remembered that drilling at such depths is new technology, operating in largely uncharted conditions. As such, the dangers of deepwater drilling in general should not be underestimated. The geology of the oil-rich region in the Gulf – as well as the deep, high-pressure conditions – makes drilling difficult, and containing oil spills challenging.
Oil Is Considered A National Security Issue
So why are oil companies being allowed to drill so deeply under the Gulf in the first place? In other words, why has the government been so supportive of deepwater drilling in the Gulf?
The answer – as Anderson and Boulanger note – is that there is a tremendous amount of more oil deep under the Gulf, and that the United States government considers oil drilling in the deep waters of the Gulf as a national security priority:
The oil and gas industry and the United States government both face tremendous challenges to explore discover, appraise, develop, and exploit vast new hydrocarbon reserves in waters deeper than 6000 feet in the ultra-deepwater of the Gulf of Mexico. Yet these new reserves of hydrocarbons are needed to offset the economically detrimental, long-term decline in production from within the borders of the United States
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