Unusual steps may have triggered oil-rig blast

WASHINGTON — Investigators homed in Tuesday on whether an uncommon sequence of events, including a decision to remove heavy drilling lubricants early from a pipeline, may have triggered the sudden surge of natural gas that led to last month's explosion and sinking of the Deepwater Horizon offshore oil rig.

The topic came up as Congress and a federal panel in Louisiana opened inquiries into the April 20 explosion, which killed 11 people and mangled a deep-water well that continues to spew 210,000 gallons of crude oil into the Gulf of Mexico daily.

As the inquiries opened, the Obama administration announced a major reorganization of the Mineral Management Service (MMS), the Interior Department agency that oversees offshore drilling.

Interior Secretary Ken Salazar said the MMS would be split in two, dividing its leasing-royalty collection function from its safety and environment enforcement responsibilities amid growing complaints that the relationship between MMS and the oil industry is too cozy.

The MMS oversees the nation's natural-gas, oil and other mineral resources and collects and distributes more than $13 billion per year in revenues from federal leases for offshore and onshore drilling.

It also enforces laws and regulations that apply to drilling operations.

Some critics have said the two roles are in conflict and are one reason the agency long has been accused of being too cozy with industry.

An internal investigation in 2008 described a "culture of substance abuse and promiscuity" by workers at the minerals agency.

The investigation by the Interior Department's inspector general found workers at the MMS royalty-collection office in Denver partied with, had sex with and used drugs with energy-company representatives.

Workers also accepted gifts, ski trips and golf outings, the report said.

Meanwhile, BP announced that the "top hat" it hopes to drop over one of the leaks 5,000 feet below the surface of the Gulf had left a Louisiana port where it was being readied. Mark Proegler, a spokesman for BP, the well's owner, said the top hat would be on the seafloor Tuesday night but would not be placed over the leak until later this week.

What triggered the explosion that sank the rig and let loose the flow of crude oil is critical to understanding not only whom to blame for what could become the worst crude spill in U.S. history, but also whether much tougher limitations should be placed on what oil companies can and cannot do when drilling in deep water.

Anthony Gervaso, the engineer aboard a supply ship parked near the rig when it exploded, told a Coast Guard inquiry in Kenner, La., that he'd learned from his captain that rig workers pulled from the water had said they had just start removing the drilling lubricant from the well when gas shot up the pipe and exploded.

Tim Probert, an executive with Halliburton, the subcontractor responsible for placing a cement plug in the well, told senators in Washington, D.C., that the dense drilling fluid had been pulled from the drilling tube and replaced with much lighter seawater before a cement plug was set to block gas and oil from coming up the pipeline.

Normally, the procedure would have been to place the plug, then switch out the drilling fluid for seawater. He said the decision to reverse the process came at the instigation of BP, the well's owner.

Asked whether the practice was an unusual sequence of events, Probert told Sen. Jeff Session, R-Ala., he couldn't answer the question, but that it had "been used on multiple occasions in the Gulf of Mexico."

As for who was responsible for determining whether it was a normal sequence of events, both Probert and Steven Newman, CEO of Transocean, which owned the rig, said it would have been up to BP as the well owner to have conversations with the MMS about that.

"As the lease operator and the well owner, that falls on BP," Newman said.

BP America President Lamar McKay told the Senate Energy and Natural Resources Committee and the Senate Environment and Public Works panel that BP had hired Transocean to drill the well, and questioned whether Transocean's blowout preventers — huge devices that sit atop the well under water and are intended to close the drilling pipe in the event of a disaster — had worked properly.

Transocean's Newman disputed BP's claim that the blowout preventers failed. Halliburton, the cement contractor responsible for sealing the well, blamed BP as the owner of the well, saying it simply was following BP's instructions.

Exasperated with the finger-pointing, Sen. Lisa Murkowski, R-Alaska, the top Republican on the Senate Energy Committee, warned the executives that their negligence could harm future offshore drilling in U.S. waters and have an impact on the country's energy policy.

"I would suggest to all three of you that we are all in this together," she said.

Information from The Associated Press is included in this report.