Tuesday, June 29, 2010

Oil Spill: The Worstest Worst Case Scenario- A Sinkhole Swallows Everything (BP)

Yesterday we had the WaPo's Joel Achenbach:

Oil spill: Even worse worst-case scenarios! (BP)
My geology professor from way back sent me his worst-case scenario for the gulf disaster:

Somewhere, you might want to bring in the Lusi mudflow in Indonesia. The Wikipedia entry has the basic story. (There are 6.8 oil barrels in a cubic meter.) Lusi is a blowout that's been going for several years. There is no present hope of containing it....
From bnet:
Apocalypse in the Gulf: Could a Sinkhole Swallow the Deepwater Horizon Well -- And BP?
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.
We know little about the underlying geology of the spill site since BP has held that information close, claiming that it’s “proprietary” data. Scientists are clamoring for BP to publicly release geological survey data on the underlying “Lower Teriary” formations (rock layer formed 65 million to 250 million years ago). Remotely operated vehicles (ROVs) are streaming video feeds of high pressure columns of oil and gas bubbling up from fissures in the sea floor — flowing from likely stress fractures in the underground piping.
A much talk-about anonymous posting at The Oil Drum, a blog often frequented by petroleum engineers and other oil-industry specialists, captures the fears of many scientists and environmentalists alike:
That the system below the sea floor has serious failures of varying magnitude in the complicated chain, and it is breaking down and it will continue to.
What does this mean? It means they will never cap the gusher after the wellhead. They cannot…the more they try and restrict the oil gushing out the bop [blowout preventer]?…the more it will transfer to the leaks below. Just like a leaky garden hose with a nozzle on it.
Don Van Nieuwenhuise, director of geoscience programs at University of Houston, told New Orleans Times-Picayune reporter Rebecca Mowbray that BP ran out of casing sections before it hit the reservoir of oil, so it switched to an inferior material — something called liner — for the remainder of the well. Consequently, the BP well has several weak spots that the highly pressurized oil could exploit. Specifically, the joints between two sections of liner pipe and the joint where the liner pipe meets the casing could be weak, said Van Nieuwenhuise.

Nieuwenhuise added that efforts by BP to try to stop the oil or gain control of it have been tantamount to repeatedly hitting the well with a hammer and sending shock waves down the pipe. “I don’t think people realize how delicate it is,” he told the paper. Nonetheless, Van Nieuwenhuise believes oil from a blown out well rupturing the casing and bubbling up through the ocean floor is unlikely — a worst-case scenario — as he ’s never actually heard of such an occurrence.

Weak joints, shock waves down the pipe, cracks and fissures in the sea bed – does a down-hole blowout seem such a remote “worst-case scenario?” Oh, and let’s not forget the incessant, abrasive-mixed plume of oil, natural gas, and “itty-bitty” grains of sediment surging through the drill piping at incredible pressures. Anyone care to wager the integrity of the pipe liner ain’t what it used to be after having been effectively sandblasted for the last 70 days?

The late Larry Flak, an engineer recognized the world over for his acumen in containing deepwater well blowouts, presciently warned back in 1997 (before drilling at depths of 30,000+ feet was feasible) of the dangers ultra-deepwater blowouts might pose:...MUCH MORE