Sedco 706: leak nothing to do with Transocean

The leak, about 160 kilometers (100 miles) off the coast of Brazil's Rio de Janeiro state. was the result of an underestimate of pressure in the offshore oil reservoir that was the target of their drilling and an overestimate of the strength of undersea rock.

As a result, high pressure oil was able to leak into the well bore hole. While the well was immediately shut off, the pressure from the so-called "kick" caused the bore-hole wall to crack and oil to seep through crevices and porous rock to the seafloor and then up into the ocean.

Chevron owns 52 percent of Frade, which is producing about 79,000 barrels of oil and natural gas equivalent a day, and is the fields operator. Petrobras owns 30 percent and a Japanese Group known as Frade Japan owns 18 percent.

The well, which is being abandoned, was drilled by Transocean from their Sedco 706 rig. Buck said the problems at the well "had nothing to do with Transocean."

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Sedco 706: Transocean rig at Brazil leak site

Chevron Corp. (CVX), the second-largest U.S. energy company, said it has halted an oil leak at the Frade project off the coast of Brazil after plugging a well.

“Fluid flow from the well appears to have ceased. The well probably contributed to the seeps that have been the source of an oil sheen that appeared on the surface of the ocean.

Chevron said yesterday that it planned to use cement and mud to seal a fissure in the sea floor that was the suspected source of the oil leak. As much as 882 barrels of crude had reached the surface, Brazil’s oil regulator, known as ANP, said yesterday, citing Chevron.

The company contracted Transocean’s Liberian-flag Sedco 706 rig to drill an appraisal well in the Frade field 230 miles (370 kilometers) northeast of Rio de Janeiro, The SEDCO 706 is a dynamically-positioned Sedco 700 design semi-submersible drilling unit capable of operating in moderate environments and water depths up to 2,000 m (6,562 ft)* using 18¾” 10,000 psi BOP and 21” OD marine drilling riser. here

Chevron, which has 51.74% interest, started production at Frade field in 2009. Partners in the field are Petroleo Brasileiro SA 30%, and Frade Japao Petroleo Ltda., a joint venture of Inpex Corp., Sojitz Corp., and Japan Oil, Gas & Metals Corp. 18.26%.