Thomas Roth, vice president of cementing for Houston-based Halliburton, disputed BP’s contention that his company’s cement job let oil and gas flow up to the Deepwater Horizon drilling rig, contributing to the blowout in the Gulf of Mexico.
“BP’s well design and operational decisions compromised well integrity,” Roth said at a National Academies hearing in Washington investigating the cause of the April 20 spill. BP workers ignored “multiple red flags” indicating the well wasn’t sealed properly and hydrocarbons could escape, Roth said.
The National Academies, which provide research on science and technology, are studying the BP spill at the request of Interior Secretary Kenneth Salazar. The hearing today, led by a panel of scientists and engineers, brought more of the finger- pointing by London-based BP and its contractors on the Macondo well that has dominated congressional hearings and other inquiries.
BP officials told the panel that Halliburton’s faulty cement recipe let gas and oil escape to the surface.
BP tested the recipe used by Halliburton as part of its internal investigation of the spill and said it didn’t contain the correct levels of hydrogen. Investigators didn’t have access to the cement actually used in the Macondo well that failed, said Kent Corser, drilling engineering manager for BP North America Gas, who was among a group of BP employees and outside contractors who conducted the investigation.
Roth of Halliburton said BP’s test didn’t use the same materials Halliburton put in its cement and followed a different manufacturing technique.
BP said the company’s well design wasn’t an issue. “We think it was a robust design,” Corser said.
Errors Halliburton cited included a decision to use six devices to center the drill pipe within the well instead of 21, the number that Roth said his company recommended. Using fewer of these centralizers made it more difficult for the cement to seal the pipe, he said.
Corser said BP workers on the rig mistakenly believed that 15 additional centralizers flown to the drill site were the wrong type to be used in the well. They proceeded with six of them.
The decision didn’t contribute to the blowout because the hydrocarbons flowed up through the pipe and not around the sides, according to Corser.
Pulling ‘Red Cord’
Donald Winter, an engineering professor at the University of Michigan and chairman of the panel, asked Roth why Halliburton proceeded if it feared the cementing would fail because of a bad well design.
“Why didn’t you pull the red cord?” Winter, a former Navy secretary, said.
Halliburton officials “didn’t see it to be an unsafe operation as it was being executed,” Roth said. He described the drilling operation as “challenging,” and said BP had “ultimate decision responsibility.”
Mark Bly, BP’s head of safety and operations who led the company’s investigation, called the accident “a multi-barrier failure incident.”
Mark Zoback, a professor of geophysics at Stanford University in California, asked whether BP’s “single completion” well design was “doomed to fail” because of the different pressures of the three reservoirs it drilled into.
Corser said BP models verified the company’s plan.
Zoback said rock formations at the bottom of the well may have broken apart, making it more difficult to close the pipe.
Panel members also pressed BP officials to describe the chain of command at the company. Bly said the report the company released Sept. 9 didn’t examine whether organizational failings at the company may have contributed to the spill and wasn’t meant to be the final word on the disaster.
“This doesn’t represent complete penetration into potentially deeper issues,” Bly said of the BP report, which placed much of the blame for mistakes that contributed to the largest U.S. oil spill on rig owner Transocean Ltd. and on Halliburton.
Najmedin Meshkati, a civil engineering professor at the University of Southern California and panel member, asked BP for more information on the tasks rig workers were required to perform and communications between the rig and onshore facilities.
Winter said the group would issue an interim report in the next month.