The gushing BP oil well is a mystery still unfolding, and late last month, a team of scientists from the Energy Department discovered a new twist: Their sophisticated imaging equipment detected not one but two drill pipes, side by side, inside the wreckage of the well’s blowout preventer on the bottom of the Gulf of Mexico.

BP officials said it was impossible. The Deepwater Horizon rig, which drilled the well, used a single pipe, connected in segments, to bore 13,000 feet below the ocean floor. But when workers cut into the wreckage to install a containment cap this month, sure enough, they found two pipes.

The discovery suggested that the force of the erupting petroleum from BP’s well on April 20 was so violent that it sent pipe segments hurtling into the blowout preventer, like derailing freight cars.

It also offered a tantalizing theory for the failure of the well’s last line of defense, the powerful pinchers called shear rams inside the blowout preventer that should have cut the pipe and stopped the rising oil and gas from reaching the Deepwater Horizon 5,000 feet above. Drilling experts say those rams, believed to be partially deployed, could have been thwarted by the presence of a second pipe.

The doubled-up drill pipe joins a list of clues that is helping scientists understand the complexities of the Deepwater Horizon accident, and from that, craft changes in how deep-water drilling is conducted.

“We still don’t really know what’s in” the well wreckage, said Energy Secretary Steven Chu, whose team discovered the second pipe using gamma-ray imaging. He added: “If there were two drill pipes down there when the shear rams closed, or two drill pipes below, is it possible that in the initial accident … there was an explosive release of force?…Did it buckle and snap?…The more we know about this, the better we can know what to do next.”

The challenge will be making enough changes to soothe policymakers’ and the public’s fears of a repeat accident, while keeping deep-water drilling economically feasible in an area that provides a third of the nation’s domestic oil.

Whether this requires halting deep-water drilling in the Gulf of Mexico is hotly debated. Last week, a federal judge overturned the Obama administration’s May decision to ban work on 33 deep-water rigs until January, when a presidential commission is expected to release its reform suggestions. The administration is appealing.

Officials are trying to plug the leak while looking for at least interim answers to fundamental questions about the oil spill. Chief among them: What part of the confluence of events that caused the disaster is unique to BP’s methods and practices, and what is common to the industry at large? What amount of government oversight can increase the safety of deep-water drilling, and at what cost?

Drilling experts and advocates, environmentalists and government officials agree so far on one point: No amount of regulation can absolutely preclude another drilling accident.

But some changes could not wait: Interior Secretary Ken Salazar has dismantled and begun to reassemble the agency charged with drilling oversight after finding it had too cozy a relationship with the oil industry and had ceded too much safety responsibility to the drillers.

Many drilling experts say there’s already ample evidence of errors designing and drilling the well beneath the Deepwater Horizon — and of officials on the rig “cutting corners” to finish a job that was expensively behind schedule. Those could be addressed, and could be penalized with civil and criminal charges, without shutting down part of the industry.

The accident “absolutely was preventable,” said Eric N. Smith, associate director of the Tulane Energy Institute. The rig, he added, lacked “a regulatory presence onboard that said, ‘I don’t care how late it is, you do it right or you go home.’ ”

The experts suggest that the most glaring mistake was a faulty cementing job in the well that was unable to handle the high-pressure oil and gas flow.

The government could prevent similar errors by hiring experienced engineers, stationing them on drilling rigs and empowering them to shut down any operation that failed to meet established safety standards, Smith said.

Administration officials acknowledge that the federal government has not provided nearly enough money or inspectors for that level of oversight.

Salazar called past and present funding levels for inspectors “woefully inadequate” and said that “you need to have the horsepower to be able to have the inspection” of deep-water drilling rigs.

He has also insisted that the drilling moratorium would give investigators crucial time to solve the mystery of why so many of the Deepwater Horizon’s “fail-safe” backups failed. That includes learning why the shear rams are partially deployed but resisting efforts to fully close.

“There clearly needs to be identified what, if anything, went wrong with the fail-safe system,” said Gene Beck, an assistant professor of petroleum engineering at Texas A&M University. “We need to understand, did something happen with the [blowout preventers] that we didn’t understand? Did they fail to function, in any way, shape or form, within their design parameters?”

Regulators could recommend additional backup systems, such as a second blowout preventer or a relief well drilled in conjunction with the initial well.

The other key to minimizing the risks of a similar blowout is economic. For example, Beck said requiring a concurrent relief well with every project could drain any profit from drilling. Smith, along with a chorus of public officials on the Gulf Coast, warns that Salazar’s six-month moratorium could drive the exploration industry out of the gulf permanently.

Environmentalists are pushing the administration to value ecological protection more highly as it updates its risk calculations.

“Safety costs a bit more,” said Chris Mann, a senior officer with the Pew Environment Group. “Our argument is that should be the cost of doing business.”

Chu said scientists won’t solve the mystery of the Deepwater Horizon — and absorb its lessons — until they exhume the blowout preventer from the seafloor and break it down.

Still, economists are beginning to tally the costs of possible reforms. A Washington-based think tank, Resources for the Future, released an analysis suggesting that if the United States brought deep-water safety regulations up to the stricter standards of nations such as Norway, the cost of a typical drilling project would rise about 10% to 20%.

That shakes out to less than half a cent per gallon at the pump.

jtankersley@latimes.com