By Yereth Rosen
ANCHORAGE, Alaska (Reuters) - An estimated 630 gallons of oil has leaked from a buried pipeline in Alaska's oldest operating oil field, state environmental officials said Wednesday.
The leak was discovered at the Swanson River oil field in the Kenai National Wildlife Refuge south of Anchorage, the Alaska Department of Environmental Conservation (DEC) said. The field, which produces both oil and natural gas, is operated by Chevron Corp.
Chevron has shut in the two wells that feed the affected pipeline, said Steve Russell, an environmental program specialist with the DEC.
Chevron could not be immediately reached for comment.
The leaking line, which carries a combination of liquids from the wells to a tank for later transport to production facilities, lies under a grassy area, Russell said. So far it is unknown whether the line is corroded because Chevron has not been able to dig it up, he said.
Other than soiling the grassy area, there has been little environmental impact, Russell said.
"There's been no wildlife impact of any kind at this time that we've determined," he said.
The Swanson River field was discovered in 1957 by Richfield Oil Co. of California. The oil find, accomplished on Richfield's first well, is credited with helping Alaska achieve statehood and helping Richfield grow into a major company that became known as Atlantic Richfield, or ARCO.
After the oil field was developed, the area encompassing it became designated as the Kenai National Wildlife Refuge.
Oil production at Swanson River was down to about 400 barrels a day in 2009, according to the Alaska Division of Oil and Gas website.
(Reporting by Manash Goswami)