Flawed Bolts Disrupt Drilling Offshore

Friday, February 8, 2013 @ 02:02 PM gHale


Faulty bolts used in safety equipment disrupted deepwater oil exploration from the Gulf of Mexico to Brazil.

Chevron Corp., Royal Dutch Shell Plc and Transocean Ltd. said U.S. regulators directed them to suspend work aboard rigs that use General Electric Co. devices connecting drilling tubes to safety gear and the seafloor.

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The companies will need to gather the equipment so they can replace defective bolts, the U.S. Bureau of Safety and Environmental Enforcement said in an alert issued Jan. 29.

Installing new bolts and resuming drilling may take as long as three weeks for each rig, Credit Suisse Group AG said. For oil companies paying upwards of $600,000 a day to rent the most- sophisticated deep-water vessels and another $500,000 a day to staff and supply each of them, the delays may be significant, said Craig Pirrong, director of the University of Houston’s Global Energy Management Institute.

The defect became apparent last month after a leak of drilling fluid linked to bolts that failed because of stress corrosion, according to the Jan. 29 alert. The regulator didn’t identify the owner of the rig or which oil company was leasing it. GE declined to identify the manufacturer of the bolts.

Nations with active offshore crude exploration are aware of the bolt defects, said Sean Gannon, a spokesman for Fairfield, Connecticut-based GE. In the Gulf of Mexico, 24 of the 83 rigs actively drilling wells at the time of the alert carried connectors that may have flawed bolts, the bureau said. Of those, six rigs got the green light to return to drilling operations.

About 30 to 40 GE customers potentially will feel the effects, Gannon said.

Anadarko Petroleum Corp., the second-largest U.S. independent oil and natural gas producer by market value, said it will be swapping out bolts at its Phobos well and a Caesar/Tonga development well.

Deep-water oil exploration involves extending steel tubes from floating rigs more than a mile to the seafloor and inserting a drill bit through the tube to carve a hole in the Earth. Five-story stacks of valves and pressure-control gear known as blowout preventers, or BOPs, go on top the well to snuff out unpredictable surges of gas and crude that pose a danger to rig crews on the surface.

The defective bolts are part of a GE product known as an H-4 Connector, an 18.75-inch (47.62 centimeters) clamp that attaches blowout preventers to the well below it and to the pipes that lead to the rig on the surface.

The Deepwater Horizon disaster prompted U.S. regulators to increase scrutiny and testing of subsea equipment and call for upgrades. BOPs cost about $45 million and weigh as much as 400 tons. Some rig operators have begun using multiple BOPs at a drilling site to speed the inspection process and bolster safety.

Statoil ASA delayed the plugging and abandonment of its Krakatoa well in the Gulf by one week to allow for workers to install new bolts, Ola Morten Aanestad, a company spokesman. Transocean owned the rig in use at the site.

Aanestad declined to say if there was any added cost to Statoil due to the delay. In general, downtime because of an issue that’s a rig owner’s responsibility, such as one related to a blowout preventer, would mean that an operator isn’t required to pay the day rate, he said.

Shell is assessing whether the bolt corrosion matter is applicable to two of its rigs in the Gulf and found it doesn’t apply to a third rig, said Kelly Op De Weegh, a spokeswoman for The Hague-based company.

Diamond Offshore Drilling Inc. is replacing bolts for connectors on about 30 of its blowout-preventer packages around the world, including two in the Gulf of Mexico, John Vecchio, executive vice president for the Houston-based company.



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