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Chevron shuts-in Cook Inlet platform Action comes after federal regulators deny special permit for continued use of corroded riser; company aims to resume production Wesley Loy For Petroleum News
Chevron has shut-in oil production on one of its offshore platforms in Alaska’s Cook Inlet after federal regulators rejected the company’s request for a repair waiver on a corroded pipeline riser.
The Anna platform, southwest of the village of Tyonek, produced an average of 858 barrels of oil per day during the first quarter of 2010, state records show.
Chevron’s subsidiary, Union Oil Company of California, in May 2009 asked the U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration for a special permit to waive compliance with pipeline safety regulations.
The issue was a corrosion “feature” on a 12-inch riser on the neighboring Bruce platform, to which Anna oil is piped on its way to the onshore Granite Point production facility. Bruce produced an average of 466 barrels a day during the first quarter.
Chevron says wall thickness sufficient A Chevron contractor pigged the riser on Feb. 10 of this year and found corrosion had eaten away 69 percent of the steel riser wall.
Chevron told regulators it was unable to repair the riser in the required timeframe, citing the inaccessible location of the corrosion feature. The riser is contained inside a leg of the Bruce platform, and the feature is toward the bottom – below the lowest tide level – at a J-curve where the riser joins with the seafloor oil line from Anna.
Chevron asserted the remaining wall thickness was more than sufficient to handle the low operating pressures, and the riser had an estimated “remaining service life” of seven years. Chevron further argued that leaving the feature unrepaired wouldn’t jeopardize public safety or the environment because the riser “is wholly contained inside” the platform leg.
Company pledges to use gas detectors In a March 5 letter to regulators, Chevron pledged to use gas detectors daily to monitor the leg’s inner atmosphere. “In the unlikely event a failure were to occur inside the leg,” the company said, the gas would signal a pipeline leak.
The riser was installed in 1967, and Chevron noted no leaks had been reported during its lifetime.
The pipeline safety administration, in an April 27 letter to Chevron, denied the special permit.
Immediate shut-in "While the agency shopped short of ordering Chevron to cease production from the Anna platform, it wrote that continuing to operate the riser meant the company was “potentially subject to enforcement action.”
Chevron didn’t take that chance.
Margaret Cooper, a spokeswoman for Chevron in Houston, issued this statement:
“Union Oil was informed of a denial of a special use permit for a line used to transport production from the Anna platform to shore. Once notified, Union Oil immediately stopped use of the line by ceasing production on the Anna platform. Union is actively working with DOT to find a solution which will allow production to restart as soon as possible. The shut-in production is approximately 900 barrels of oil per day. Agency critical of Chevron’s proposal The state Petroleum Systems Integrity Office opposed Chevron’s request for the repair waiver.
The PSIO said Chevron’s proposal to conduct weekly flyovers to look for oil sheens was “both impractical and dangerous.” The office also questioned the accuracy of the pigging, and recommended “a pro-active approach to this problem through engineered solutions or replacement of the riser.”
The PSIO added: “Alaska is under a national environmental microscope. Aside from the regulatory matters, the political and environmental ramifications of a spill in Cook Inlet are grave and if oil is released the consequences will impact our entire oil and gas industry.”
Significance of Anna platform The Anna platform shut-in adds to Chevron’s troubles in Cook Inlet, where the company in recent years has touted plans to try to boost the region’s tired oil output. Most notably, eruptions of Redoubt volcano idled oil production for months in 2009 on the west side of Cook Inlet.
Anna appeared to have been a significant part of Chevron’s strategy. In 2008 the company drilled two wells from the platform seeking new oil in the Granite Point field. The company later said, however, that the results were disappointing.
Petroleum News asked Cooper if Chevron might simply replace the corroded riser, and whether the shut-in would preclude future use of the Anna platform for drilling. Cooper hadn’t replied by press time.
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