Transocean Ltd., which owned the Deepwater Horizon rig that was destroyed when the Macondo well exploded last year in the Gulf of Mexico (GOM), on Wednesday directed the majority of the tragedy to BP plc, which operated the well and was leasing the rig.

The Swiss-based driller commissioned an “internal investigation team,” which included “experts from relevant technical fields and specialists” to analyze the information and determine the causes of the fatal accident, which killed 11 men who were working on the rig platform.

“The report concludes that the Macondo incident was the result of a succession of interrelated well design, construction and temporary abandonment decisions that compromised the integrity of the well and compounded the likelihood of its failure,” the report stated.

“The decisions, many made by the operator, BP, in the two weeks leading up to the incident were driven by BP’s knowledge that the geological window for safe drilling was becoming increasingly narrow.” Transocean’s investigation team traced the tragedy to four “overarching” issues:

BP was reviewing the report and had no comment.

Halliburton Co., which was faulted in Transocean’s report for not adequately testing cement barriers in the Macondo well, said in response that it remained “confident that all the work we performed with respect to the Macondo well was completed in accordance with BP’s specifications for its well construction plan and instructions,” and said the contract protected the company from liability.

“Deepwater operations are inherently complex and a number of contractors are involved, which routinely make recommendations to a single point of contact, the well owner,” Halliburton stated.

Transocean’s findings that faulted BP for most of the deepwater incident came as “no surprise” to analysts with Tudor, Pickering, Holt & Co. Inc. (TPH). The report, they noted, acknowledged that all the parties involved in the Macondo well drilling — including Transocean personnel — had misinterpreted the results of a negative pressure test, which ultimately led to the explosion. In any case, however, “liability is ultimately going to be decided by courts.”

Elsewhere, industry critic Rep. Ed Markey (D-Mass.) said the “circular finger-pointing contest” between the companies involved is proof that there needs to be tougher safety drilling regulations.

Transocean’s report “says little to shed new light on the details of the disaster, but the problems identified by the spill commission continue to cry out for congressional action to pass comprehensive safety standards for deepwater offshore drilling,” said Markey. “The oil industry should share responsibility for keeping their workers and American waters safe, instead of relying on their lawyers to stake out the best position for their company following a disaster.”

Transocean’s investigation began in the days immediately following the incident, but investigators didn’t have all of the evidence, the company acknowledged.

“The loss of evidence with the rig and the unavailability of certain witnesses limited the investigation and analysis in some areas. The team used its cumulative years of experience but did not speculate in the absence of evidence. The report of the team does not represent the legal position of Transocean, nor does it attempt to assign legal responsibility or fault.”

The report and supporting documents are available at www.deepwater.com.

In related news Weatherford International, which provided casing components for the Deepwater Horizon rig, agreed to pay BP $75 million in exchange for indemnity against compensatory claims in the multidistrict litigation (MDL). The $75 million is to be part of BP’s $20 billion Gulf Coast Claims Facility, which was set up to compensate Gulf Coast residents and businesses that suffered economic loss as a result of the spill.

The Weatherford settlement is the second BP has reached with a partner in the oil spill litigation. In May Japan’s Mitsui Ltd. agreed to a $1.1 billion settlement (see Daily GPI, May 23). Mitsui affiliate MOEX USA owned a 10% stake in the Macondo well. BP has MDL pending in U.S. District Court for the Eastern District of Louisiana against other related partners, which include Anadarko Petroleum Corp., a 25% stakeholder in the Macondo well, as well as Halliburton and Cameron International.

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