In a lengthy prepared statement, Halliburton said it believed there are "significant differences" between Halliburton's own tests of its cementing practices used at the well, and those tests conducted by Chevron on behalf of the commission.
"The Commission tested off-the-shelf cement and additives, whereas Halliburton tested the unique blend of cement and additives that existed on the rig at the time Halliburton's tests were conducted," the Halliburton statement said. "Halliburton also noted that it has been unable to provide the
Commission with cement, additives and water from the rig because it is subject to a Federal Court preservation order but that these materials will soon be released to the Marine Board of Investigation."
The statement said any further comment on Chevron's activities would be "premature, and should await careful study and understanding of the tests by Halliburton and other industry experts."
Halliburton did defend its own tests on the cement used at Macondo. Two of four tests cited by the presidential commission on the spill, Halliburton said, were in February and were described as "preliminary." The statement criticizes a commission allegation that the cement slurry tests in February were similar to that used at Macondo.
Turning its attention to April tests, Halliburton says the first cement test that month is "irrelevant, because the laboratory did not use the correct amount of cement blend." Halliburton also says BP was made aware of that fact, and that a panel allegation to the contrary is not correct.
The statement then concedes that a foam stability test was not conducted on the final batch -- the "nine gallon formulation" that included nine gallons of retarder per 100 sacks of cement. Other tests were run on that batch, Halliburton said.
On Thursday, a four page letter to the commission by staff lawyers noted that just one of four tests that Halliburton "ran on the various slurry designs for the final cement job at the Macondo well indicated that the slurry design would be stable."
The letter from the lawyers added: "Halliburton may not have had -- and BP did not have -- the results of that test before the evening of April 19, meaning that the cement job may have been pumped without any lab results indicating that the foam cement slurry would be stable." The lawyers concluded that, "Halliburton [and perhaps BP] should have considered redesigning the foam slurry before pumping it at the Macondo well."
The lawyers emphasized in their letter to the commissioners that, "even if our concerns regarding the foam slurry design at Macondo are well founded, the story of the blowout does not turn solely on the quality of the Macondo cement job."
Halliburton's criticism of BP starts by saying BP should have conducted a cement bond log test, which it describes as "the only means available to evaluate the integrity of the cement bond. BP, as the well owner and operator, decided not to run a cement bond log test even though the appropriate
personnel and equipment were on the rig and available to run that test."
Following the cementing, Halliburton said in the statement that the well was not flowing. But following the "misinterpreted" negative flow tests, mud in the production casing was displaced with seawater, "allowing the well to flow." "Given these numerous intervening causes, Halliburton does not believe the foam cement design used on the Macondo well was the cause of the incident," it concludes.
Those "intervening causes" were a litany in the Halliburton statement, all of which have been cited before by observers of BP's actions.
For example, Halliburton cites a misinterpretation of a negative pressure test: "Had they accurately interpreted the negative tests, remedial action, if necessary, would have been possible." The use of a long string casing in the well "reduced the number of barriers to annular flow to only two, the cement and the seal assembly." A float collar test is cited by Halliburton, which says BP personnel on the rig "were concerned with the high amount of pressure needed to convert the float collar" which could have resulted in float collar or casing damage.
Halliburton claims in the statement that it told BP it was using an inadequate amount of centralizers on the casing string: six. "Whether the hydrocarbons escaped through the annulus [the area between the casing and the wall of the well] or the casing, the decision to use an inadequate number of centralizers remains relevant because cement channeling can provide a flow path of hydrocarbons into the wellbore," Halliburton said.
