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Conoco cleaning pipelines more often Kuparuk lines formerly cleaned every six months; those piggable now being cleaned every month; line that leaked out of service
The Associated Press
ConocoPhillips has stepped up its efforts to prevent corrosion-related leaks in its pipelines in the Kuparuk oil field on Alaska’s North Slope.
The move comes after leaks in pipelines earlier this year damaged the reputation of BP, operator of the Prudhoe Bay oil field, the nation’s largest.
Kuparuk is the nation’s third-largest oil field.
Until recently, Conoco ran cleaning pigs through a key network of large Kuparuk pipelines every six months. Beginning in June, the company switched to a monthly pigging schedule and went to a “more aggressive” type of pig to better scrape sediment or other solid material out of the pipes, according to the Anchorage Daily News.
Sediment buildup suspected Federal regulators suspect sediment buildup was a factor behind severe corrosion inside two transit pipelines in the Prudhoe Bay oil field, which lies just east of Kuparuk. The corrosion led to two leaks, one in March that was the worst oil spill ever on the North Slope tundra and the other that forced a partial shutdown of the field.
BP’s Prudhoe problems have drawn scrutiny from federal criminal investigators, members of Congress and the U.S. Pipeline and Hazardous Materials Safety Administration. Critics say BP was lax in maintaining its pipelines.
The federal pipeline administration hasn’t limited its inquiry to BP. The agency requested information from ConocoPhillips on how it was safeguarding its own pipelines against corrosion, said company spokeswoman Dawn Patience.
In two reports provided to federal pipeline regulators, Conoco indicated that it had stepped up pigging in the main pipeline network within the Kuparuk field. Inspection of other pipelines also increased.
The reports say no serious corrosion has been found in Conoco-run pipelines. But they also say that for technical or design reasons, some pipes can’t be cleaned with pigs or tested for corrosion with so-called smart pigs. Those are devices that assess the condition of the pipe, looking for areas where the pipeline wall is thin.
Using other technology, Conoco said it found 12 bad spots in Kuparuk’s oil system pipeline network. The worst involved a 43 percent wall thickness loss, which is not considered dangerous by industry standards.
One line out of service after leak However, at least one Kuparuk pipeline this year developed holes, according to the Alaska Department of Environmental Conservation. Workers on March 9 noticed an icicle hanging from a 24-inch diameter pipeline at a Kuparuk drill site. The icicle had formed at one of the holes.
Spill responders found that up to 500 gallons of oily water had leaked onto the tundra. They collected another 200 gallons in a catch basin.
An investigation determined that the holes were caused by internal corrosion eating away at the steel wall. Patience said the pipeline is no longer in service.
Conoco did not honor repeated requests for an interview with its corrosion managers.
Patience provided this statement Nov. 13:
“Conoco Phillips reviews and updates our North Slope corrosion, monitoring and mitigation program on a continuous basis. In 2005 we spent approximately $30 million on corrosion monitoring and mitigation in Alaska, and this year we will spend approximately $36 million.”
The DEC report says the amount of corrosion-blocking chemicals being pumped into the pipeline was significantly lower than it should have been for six months last year “due to pump problems” and a lag in fixing the equipment.
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