flickr imagebyGreenpeace USA 2010
Right from the beginning, it was reported right away-- that Halliburton's job was to cement and seal the well casing. But I misunderstood what that meant. I took it to mean that Halliburton's job was to seal the connection between the well-head and the top of the pipe that was drilled 18,000 feet into the ground. Wrong.
Halliburton's job was to seal the well casing. When a well like the Gulf disaster well on BP's Macondo prospect oil field is drilled, they start with a big hole-- about 22 inches in diameter. Then, after a few or five thousand feet, they go to a smaller diameter, say 16 inches, then 12 inches, 11 inches, 9 inches. That initial drilling hole is the well casing. It's like a several mile long inverted cone. When the well is completed, they put a heavier duty four inch pipe all the way down the well. That's what the oil is supposed to flow through.
Halliburton's job was to seal the well casing with concrete-- all three plus miles of casing, so the four inch pipe was surrounded with concrete.
New disclosures make it clear that BP made decisions to cut costs which reduced the safety of the job Haliburton did. A huffingtonpost.com article reports that, as part of an investigation, congressmen Henry Waxman and Bar Stupak wrote:
Despite warnings from its own engineers, "BP chose the more risky casing option, apparently because the liner option would have cost $7 to $10 million more and taken longer," Waxman and Stupak said.Now, there is speculation from multiple sources that there were problems with the seal job. Washingtonblog.com reports, using multiple sources and videos, that there is concern that the casing may have been compromised, causing leaks far below the surface of the sea floor. They report that Cameron international, the manufacturer of the BOP at the top of the wellhead, that was supposed to shut the well, may have broken parts from the casing blocking the BOP from closing. Washingtonblog also reports,In the brief e-mail, Morel said the company is likely to make last-minute changes in the well.
"We could be running it in 2-3 days, so need a relative quick response. Sorry for the late notice, this has been nightmare well which has everyone all over the place," Morel wrote.
BP apparently rejected advice of a subcontractor, Halliburton Inc., in preparing for a cementing job to close up the well. BP rejected Halliburton's recommendation to use 21 "centralizers" to make sure the casing ran down the center of the well bore. Instead, BP used six centralizers.
In an e-mail on April 16, a BP official involved in the decision explained: "It will take 10 hours to install them. I do not like this." Later that day, another official recognized the risks of proceeding with insufficient centralizers but commented: "who cares, it's done, end of story, will probably be fine."
Indeed, loss of integrity in the well itself may explain why BP is drilling its relief wells more than ten thousand feet beneath the leaking pipes on the seafloor (and see this).
Yesterday, recently-retired Shell Oil President John Hofmeister said that the well casing below the sea floor may have been compromised:
[Question] What are the chances that the well casing below the sea floor has been compromised, and that gas and oil are coming up the outside of the well casing, eroding the surrounding soft rock. Could this lead to a catastrophic geological failure, unstoppable even by the relief wells?
John Hofmeister: This is what some people fear has occurred. It is also why the "top kill" process was halted. If the casing is compromised the well is that much more difficult to shut down, including the risk that the relief wells may not be enough. If the relief wells do not result in stopping the flow, the next and drastic step is to implode the well on top of itself, which carries other risks as well.
As noted yesterday in The Engineer magazine, an official from Cameron International - the manufacturer of the blowout preventer for BP's leaking oil drilling operation - noted that one cause of the failure of the BOP could have been damage to the well bore:
Steel casing or casing hanger could have been ejected from the well and blocked the operation of the rams.
Oil industry expert Rob Cavner believes that the casing might be damaged beneath the sea floor, noting:
The real doomsday scenario here" is if that casing gives up, and it does come through the other strings of pipe. Remember, it is concentric pipe that holds this well together. If it comes into the formation, basically, you"ve got uncontrolled [oil] flow to the sea floor. And that is the doomsday scenario.
Cavner also said BP must "keep the well flowing to minimize oil and gas going out into the formation on the side"
And prominent oil industry insider Matt Simmons believes that the well casing may have been destroyed when the oil rig exploded. Simmons was an energy adviser to President George W. Bush, is an adviser to the Oil Depletion Analysis Centre, and is a member of the National Petroleum Council and the Council on Foreign Relations.
Business week reports on details from the Waxman-Stupak congressional investigative committee letter,
Well Design Five days before the blast, BP concluded the method to secure the final 1,200 feet of well, called a liner/tieback, was too time-consuming and expensive, the lawmakers said. Using an alternative called a long-string casing would save at least three days and about $7 million to $10 million.A liner/tieback approach provided multiple barriers to block the flow of gas that could trigger an explosion. The single steel liner had two places to seal the well: at the cement on the bottom of the sea and at the wellhead.
"BP was aware of the risks of the single casing approach," the lawmakers said.
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