Apocalypse in the Gulf: Could a Sinkhole Swallow the Deepwater Horizon Well — And BP?
By David Phillips
BP has confirmed that the failed blowout preventer (BOP) on its Deepwater Horizon well in the Gulf of Mexico is tilting sideways at an acute angle 12 to 15 degrees from perpendicular. Geologists and petroleum engineers are now debating the worst case scenario: growing evidence that the Macondo discovery well’s casings beneath the ocean floor have been irreversibly damaged, possibly to such an extent that it may be impossible to cap the well.
The Deepwater Horizon had recently completed promising exploratory drilling — to a vertical depth of about 18,000 feet (3.4 miles as measured from the rig floor), not including vertical depth to canyon floor (about 5,000 feet) — when it exploded as the rig crew prepped a temporary seal for the well on April 20.
BP spokesperson Toby Odone acknowledged to reporters last week that the 45-ton BOP was tilting, which the company attributed to a shift in the collapsed riser piping (from the rig accident).
Since the failure of last month’s “top-kill” effort to stem the flow, knowledgeable scientists have argued about the potential significance of BP’s inability to maintain enough topside pressure — to “squash” the column of superheated fluids erupting upward — during the plugging efforts. One popular hypothesis making the rounds online is that the underground well casing is fractured beyond repair. Some geologists and petroleum engineers argue that the top-kill failure could have resulted from too much “kill mud” leaking out of cracked pipe casings into the surrounding rock formation instead of flowing deeper into the well. (Click image for a larger version.)
BP cites a broken disk inside the well as the cause of the top-kill failure. Admiral Thad Allen, the incident commander for the BP oil spill response, has confirmed on recent conference call updates that structural problems in the well casing of the sunken Deepwater Horizon rig cannot be ruled out. Commenting on BP’s decision to halt the top-kill contingency, Allen — President Obama’s point person — said:
There was some discussion at that point about the uncertainty of the — of the condition of the casings in the wellbore which you would want to do is drive so much mud down there and such a pressure that you might cause a problem and the problem was they (scientific summit that included Interior Secretary Ken Salazar and Energy Secretary Steven Chu) didn’t know and they still don’t know the condition of the wellbore. For that reason, they erred on the side of safety on how much pressure they would exert, and when they got near those pressures without having success in killing the well — killing the well, that’s when they backed off.