Post-spill repairs continue at Lisburne

Work continues in the wake of a 2011 spill in the Lisburne field on Alaska’s North Slope, according to a final “situation report” the state Department of Environmental Conservation issued Feb. 12.

An estimated 1,764 gallons of blended methanol and produced fluids spilled onto a gravel pad and wet tundra after an 8-inch line in a piping system known as a test header ruptured. Contractors for field operator BP Exploration (Alaska) Inc. discovered the spill on July 16, 2011.

The spill volume was somewhat lower than the original estimate.

The pipeline failure occurred during a pressurized leak test to check newly installed valves.

The line ruptured underground at a roadway crossing at the L-1 drill site, the DEC situation report said.

Substantial work has been done to clean up the site and rehabilitate tundra vegetation.

And some engineering work is ongoing.

“BPXA redesigned the pipeline at the road crossing, eliminating some of the 90-degree elbows and changing the pipe profile to elevate the pipeline above water level,” the report said. “Installation of the newly fabricated pipeline segment should be completed in spring 2013. The test header pipeline has remained out of service.”

The ruptured line was used to divert production from wells to a test separator required by regulation, not to transport production to the Lisburne processing facility, BP said at the time of the spill.

The Lisburne field is a reservoir located within the BP-operated Prudhoe Bay unit. Lisburne began production in 1986.

—Wesley Loy