Experts: “Very high level of concern for the integrity of the well”; “That’s all people are talking about”
June 20th, 2010
Oil spill containment efforts could be putting strain on damaged well, New Orleans Times-Picayune, June 18, 2010:
As BP and the government have plotted ways to shut down the renegade oil well in the Gulf of Mexico or contain its spewing oil over the past two months, their options have been limited by concerns about the potential for blowout in the underground portion of the well.
In a well of questionable design with a questionable cement job that’s gone through a major explosion, too much pressure on the well, could trigger a rupture, sending oil pushing through fissures in the rock of the ocean floor and bubbling up through the seabed, where it can’t be contained.
That’s why BP abruptly stopped the “top kill” efforts to seal the well May 28 after the company previously had said the procedure would continue for a few more days. It’s also why the company is continuing with efforts to contain the oil flowing out of the well rather than seal the well outright by adding another blowout preventer on top of the malfunctioning one. …
U.S. Coast Guard Admiral Thad Allen acknowledged as much at a briefing Thursday.
“One thing that nobody knows is the condition of the well bore … We don’t know if the well bore has been compromised or not. One of the reasons we did not continue with top kill at higher pressures, there was a concern that if we increased the pressure too hard it might do damage to the casings and the well bore. What we didn’t want was open communication of any oil from the reservoir outside the well bore that might get into the formation and work its way to the sub sea floor and then result in uncontrolled discharge at that point. …
“We don’t know exactly the condition of the well bore …That’s the reason we didn’t go … to excessive pressures on the top kill and decided that we’d deal with containment and then go for the final relief well.” …
The integrity of the well has become a major topic of discussion among engineers and geologists.
“Everybody’s worried about all of this. That’s all people are talking about,” said Don Van Nieuwenhuise, director of geoscience programs at University of Houston. He said the things that BP has being doing 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.”
“There is a very high level of concern for the integrity of the well,” said Bob Bea, the University of California Berkeley engineering professor known to New Orleanians for investigating the levee failures after Katrina, who now has organized the Deepwater Horizon Study Group. Bea and other engineers say that BP hasn’t released enough information publicly for people outside the company to evaluate the situation.
Florida Senator Bill Nelson also expressed concern. The Democrat sent BP a letter asking for information and documents relating to any breaks in the well casing beneath the sea floor, any monitoring that BP is doing of the structural integrity of the well, any monitoring of the nearby sea floor for oil leaks, and whether any oil or gas has escaped beyond the boundaries of the casing.
BP spokesman Toby Odone said Friday his company can shed little light on the subject. “We don’t know” anything about the condition of the underground portion of the well, Odone said. “We don’t know whether the casing inside the well is damaged.”
When wells are drilled, engineers send links of telescoping pipe down the hole, and those links are encased in cement. The telescoping pipe, called casing, unfolds like a radio antenna, only upside down, so the width of pipe gets smaller as the well gets deeper.
The cement and layers of casing are normally quite strong, Van Nieuwenhuise said. But with the BP well, there are several weak spots that the highly pressurized oil could exploit. BP ran out of casing sections before it hit the reservoir of oil, so it switched to using something called liner for the remainder of the well, which isn’t as strong. The joints between two sections of liner pipe and the joint where the liner pipe meets the casing could be weak, Van Nieuwenhuise said.
Bill Gale, an engineer specializing in fires and explosions on oil rigs who is part of Bea’s Deepwater Horizon Study Group, said the 16-inch wide casing contains disks that are designed to relieve pressure if necessary. If any of those disks popped, it could create undesirable new avenues for the oil to flow.
Bea said there are also concerns about the casing at the seabed right under the blowout preventer. …
In an answer to a question, Bea said, “Yes,” there is reason to think that hydrocarbons are leaking from places in the well other than the containment cap.
“The likelihood of failure is extremely high,” Bea said. “We could have multiple losses of containment, and that’s going to provide much more difficult time of trying to capture this (oil).” …
Bea said BP isn’t sharing enough information for others to know. If there is oil and gas escaping from the sides of the well, it could erode the sediments around the well and eat away at the support for all the heavy equipment that sits above. Bea said reports that BP is using an inclinometer [to monitor the blowout preventer's tilt] is significant news. “It tells me that they are also concerned,” he said.