Halliburton technical adviser Jesse Gagliano testifies during the Deepwater Horizon joint investigation hearings by the U.S. Coast Guard and the Interior Department's Bureau of Ocean Management Regulation and Enforcement on Tuesday in Houston. (Photo: Melissa Phillip, pool, The Associated Press)

Jesse Gagliano, a Halliburton employee who worked on cementing BP’s Macondo well, testified Tuesday in Houston that he verbally warned BP officials that their well plan increased the risk of gas leaks and questioned those plans by e-mail. But he wasn’t able to get the company to change the process before the well kicked gas, sparking the deadly explosion and ultimately leading to the largest oil spill in U.S. history.

One of the people he talked with was the well’s designer, BP engineer Brian Morel. Morel signed off on BP’s controversial well plan and referred to it as a “nightmare well” in an internal e-mail days before the explosions. On Tuesday, he became the second witness to refuse to testify before the joint Coast Guard and Bureau of Ocean Energy Management panel, invoking his Fifth Amendment right not to incriminate himself.

On April 15, five days before the explosions, Gagliano ran a computer model for BP’s engineers that assumed BP would use 21 devices called centralizers to prevent the cement Halliburton was providing from channeling in the hole, thus weakening the well seal.

But that same day, Morel sent an e-mail message to Gagliano saying BP was going to use only six centralizers, adding that it was “too late” to send any more of the safety devices.

Gagliano’s models showed a high risk of gas flow in a well with so few centralizers. He appealed to BP officials who worked in his office to use 21 centralizers.

It is this methane gas that flowed up the 3-mile-deep hole, up a mile-long riser through the Gulf waters and to the rig to ignite, killing 11 men. But it’s not clear whether the gas that burst out of the well leaked in through cement linings or whether it came up from the bottom and through the middle of the hole.

After expressing his concern, Gagliano said he stayed up late the night of April 15 with two BP officials and persuaded them to arrange for sending 15 more centralizers to the rig. The devices arrived the next morning, but later Gagliano found out BP decided not to use them. BP engineering team members Morel, Mark Hafle and Brett Cocales never responded to his e-mail asking why. (FULL STORY)