Chevron Corp. 's blowout preventer - "the last line of defence" against a massive oil spill off Newfoundland - has shortcomings that could hamper efforts to respond to an emergency, weaknesses that have prompted the company to develop a new, more efficient well killer.
Chevron is drilling an exploration well in 2,600 metres of water in the North Atlantic's stormy Orphan Basin area, and company executives sought to re-assure a Senate committee on Thursday that the project can be done safely with virtually no chance of a major spill. But Chevron officials acknowledged that the blowout preventer used on the drill ship Stena Carron can't cut through certain lengths of drill pipe, a fact that complicates its blowout failsafe procedures.
BP PLC's catastrophic blowout in the Gulf of Mexico has raised questions about the reliability of blowout preventers (BOPs) after the 450-tonne, valve-like device failed to activate and shut down BP's out-of-control well.
Investigators are not sure why the equipment failed. BP says the cause won't be known until it can retrieve the equipment from the sea floor, 1,500 metres beneath the surface, and examine it. But in the aftermath of the accident, questions are being raised about the reliability of the blowout preventers.
Several studies, including a 2004 report to U.S.'s Mineral Management Services, have suggested there may be problems with the BOP technology in ultra-deep water where international oil companies are increasingly focusing their exploration efforts.
The MMS report warned that BOPs do not function as efficiently in deep water as they do at shallow depths, and found that only three of 14 new offshore rigs tested were able to shear drilling pipe - a necessary step in halting a blowout - at their maximum-rated depths.
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Chevron itself has been working since 2007 to develop a safer blowout preventer - one that would further reduce the risk of blowout by simplifying the system. But that system is not ready for deployment.
Newfoundland and Labrador Premier Danny Williams has played down the impact of the major spill off the coast, saying the oil would not touch shore. But Chevron executives said Thursday that a blowout would be a "disaster" that would threaten seabird populations and, potentially, fisheries.
Current blowout preventers employ a three-stage process in which the equipment must first slice through the drill pipe with shear rams, lift the pipe out of place, then activate seal rams that close the BOP stack and seal the well. Chevron's "Alternative Well Kill System" would do the job in one step, reducing the potential for a malfunction.
At the Senate committee hearing in Ottawa, Chevron executives conceded there are some extra-thick sections of the drill pipe that current blowout preventers would not be able to cut. In the event of an emergency, drillers would check the positioning of those "collars" and, if one was in the way, raise or lower it before the BOP could be activated and the well shut down.
They rejected suggestions that the blowout preventers do not function as well in ultra-deep water due to the tremendous subsea pressure, arguing that the equipment is manufactured specifically to operate at such depths.
Chevron says it ensures the blowout preventer will work in an emergency through proper well design and extensive training for drilling crews. The company also says it expects to avoid those emergency situations by following proper well control methods using cement casing and heavy drilling fluids - areas where BP has been criticized.
"We are aware of the problems" with the BOPs. Chevron vice-president David MacInnis said in an interview. "We make sure we are designing the wells with those facts in mind."
Environmentalists say the MMS study - and similar ones that have come to light in the aftermath of the BP disaster - undermine assurances from Chevron and the federal-provincial regulatory board about the safety of the operation.
"Industry experts have proudly compared the technological feat of deep offshore drilling to walking a tightrope," said Craig Stewart of WWF-Canada.
"With this revelation about blowout preventers, it appears Chevron has holes in its safety net and knows it."
Retired Royal Dutch Shell PLC senior engineer Robert Bea said the blowout preventer can be an effective defence, but drill crews need to know the precise position of the drill pipe before the BOP preventer is activated.
"This is as much a software issue as a hardware issue," said Mr. Bea, a civil engineer who served on the Obama's administration's interim committee that did an initial review of the BP accident. "You've got to have your hardware and software carefully aligned. If they are not aligned, you crash."
Mr. Bea said there been ongoing concerns about the reliability of blowout preventers in the Gulf of Mexico, with failure rates as high as 50 per cent. But he added that proper equipment would minimize the risks, so long as companies are prepared to pay top dollar for it.
In the aftermath of the BP disaster, Chevron had its own in-house specialists and outside consultants review the blowout preventer. It has tested the operation of the system both on the surface and at 2,600 metres, and will do so every three weeks.
The drill ship, Stena Carron, is equipped with safety features that were not available on BP's Deepwater Horizon. They include a variety of automatic shutdown systems for the blowout preventers, should it experience loss of power or hydraulics, and an acoustic transponder that can send shutoff signals from other boats should the Stena Carron be lost or abandoned.
Mark MacLeod, Chevron's vice-president for East Coast operations, defended the company's safety procedures. He noted that Chevron has already drilled 300 deepwater wells without incident - though some senators noted that BP could have made a similar boast seven weeks ago.