NEW ORLEANS, La. — BP’s cement contractor on the Deepwater Horizon rig has discovered cement samples possibly tied to the ill-fated drilling project that weren’t turned over to the Justice Department after the 2010 oil spill, a lawyer for the contractor said Thursday.

Halliburton lawyer Donald Godwin told U.S. District Judge Carl Barbier that the company believes the material found Wednesday at its laboratory in Lafayette has no bearing on the ongoing trial to assign responsibility for the nation’s worst offshore oil spill.

A plaintiffs’ attorney, Jeffrey Breit, countered that the samples are cement a Halliburton employee used for testing of BP PLC’s Macondo well before the disaster.

The blowout and explosion on April 20, 2010, killed 11 workers and led to the enormous spill in the Gulf of Mexico. The failure of the cement job to seal the well was part of a complex web of mistakes that led to the April 20, 2010, blowout, according to a series of government probes.

In an email to the court late Wednesday, Godwin says Halliburton is investigating whether the cement samples should have been turned over in response to subpoenas.

“The lab was immediately instructed to photograph the materials and to continue to hold them,” Godwin wrote.

Godwin’s email said the newly discovered samples appear to be associated with the Kodiak well, which the London-based energy giant BP and its contractor Transocean were drilling in the Gulf.

The non-jury trial began Feb. 25 and could last months. Barring a settlement, Barbier could decide how much more money that BP and its contractors owe for their roles in the catastrophe. BP could be on the hook for nearly $18 billion in penalties under the Clean Water Act if the judge finds that it acted with “gross negligence.”

During the trial’s opening statements, plaintiffs’ attorney Jim Roy said Halliburton used a cement blend from the Kodiak well in designing the Macondo well. The Kodiak cement contained an additive, a defoamer that “destabilizes and is incompatible with foam cement,” Roy said.

“So why would Halliburton risk using this leftover Kodiak cement on the Macondo well and try to convert it to a foam cement when it had defoamer in it? The evidence will show Halliburton was able to save time and save money by doing so,” Roy said.

Godwin’s email said Halliburton lawyers didn’t have any idea that materials associated with the Kodiak well were still in the company’s possession before hearing testimony Monday from Timothy Probert, a Halliburton president who served as its chief safety officer at the time of the disaster.

Probert had testified he learned of some “irregularities” in tests that Halliburton employees performed in the spill’s aftermath.

Probert didn’t specify the nature of those irregularities, but Breit claimed Halliburton employees conducted “off-the-record” cement tests and didn’t write down some test results because they feared how they could affect spill-related litigation.  

While questioning Probert, Breit said Kodiak cement that Halliburton had stored by April 30, 2010, was no longer listed as being in its possession as of July 20, 2010.

“Do you have any explanation why someone from Halliburton would have violated a preservation order of this court and removed the very Kodiak cement that was being used on the Macondo well?” Breit asked.

Godwin objected, saying there was no evidence that a court order had been violated.

“It’s unfair for anybody to stand here in this courtroom and say that my client took any of that blend out of that locker, which it did not do,” he added.

Barbier also heard several hours of testimony Thursday from marine safety expert Geoff Webster, a plaintiffs’ expert who concluded Transocean failed to properly maintain the Deepwater Horizon or adequately train its crew members. Webster said Transocean shouldn’t have allowed the rig to drill for nine years without bringing it back to shore for shipyard repairs.

“Clearly,” he said, “Transocean was more interested in production than maintenance.”