A US judge has ordered urgent tests on the cement contractor Halliburton used to seal the BP oil well that blew out catastrophically in the Gulf of Mexico.
US district judge Carl Barbier said some of the components may be “deteriorating over time” and that tests should be done “as soon as reasonably practicable”.
The cement components had been subpoenaed by US government investigators looking into what caused the 20 April blow-out of the BP well being drilled by the Deepwater Horizon rig. Halliburton was hired to seal the well with cement.
The explosion aboard the Deepwater Horizon killed 11 workers and led to a spill of more than 170 million gallons of crude oil in the Gulf.
Halliburton’s cementing work on the well has jumped to the forefront of investigations into the explosion. On Thursday, President Barack Obama’s oil spill commission said tests performed before the blow-out should have raised doubts about the cement used to seal the well.
The cement mix’s failure to prevent oil and gas from entering the well has been identified by BP and others as one of the causes of the accident.
Judge Barbier, who is overseeing lawsuits filed after the explosion, ordered tests on the same batch of cement used by drillers in the hours before the explosion.
Halliburton expected government investigators to retrieve the batch of cement components next week, said company spokeswoman Cathy Mann.
But Kenneth Arnold, a member of the National Academy of Engineering who served as an adviser to the US department of interior during its probes into the Deepwater Horizon explosion, questioned the importance of doing the tests on the cement components.
“The samples are old now,” he said. “Whatever tests they do now are going to be open to interpretation.” And he added that it would be hard to simulate the cement foam’s properties in a laboratory and compare them with what happened inside the well.
Independent tests conducted for the commission by Chevron on a nearly identical mixture also concluded that the mix was unstable.
Halliburton has said it was unable to give the presidential commission the cement mix used on the Deepwater Horizon rig because that batch was being held as evidence for the continuing government investigation.
Judge Barbier’s order released Halliburton to hand over some of the mix to investigators.
The judge wants tests on 1l of ZoneSeal-2000 and 8.5l of SCR-100 in Halliburton’s possession.
On its website, Halliburton describes SCR-100 as a “cement retarder” that helps make a “uniform slurry consistency from batch to batch”. SCR-100 is “synthetically manufactured, which guarantees product uniformity”.
ZoneSeal is the product name for Halliburton’s foam cement, a slurry created by injecting nitrogen into cement to secure the bottom of the well. The decision to use foam cement has been criticised by outside experts.
Halliburton said there were “significant differences” between the Chevron tests and those it performed. It said Chevron “tested off-the-shelf cement and additives” while it tested “the unique blend of cement and additives that existed on the rig at the time”.
Halliburton says an April test, performed before the explosion, resulted in a stable foam and has also pointed blame at BP, saying the company failed to take steps to make sure the cement job worked.
For its part, BP has said a bad cementing job contributed to the blow-out. and a “more thorough review and testing by Halliburton” and “stronger quality assurance” by BP’s well team might have identified weaknesses in the plan for cementing.