Pipe breaks, spilling oil at Prudhoe drill site

At 10:30 a.m. on Dec. 21 a six-inch production line carrying oil, water and natural gas from a well head at drill site six in the Prudhoe Bay field broke apart, spraying out a mixture of oil and produced water, releasing natural gas, demolishing the back of the well house and blowing open the well house front doors.

BP spokesman Steve Rinehart told Petroleum News Dec. 22 that the pipe had ruptured at a weld and that an on-site BP operator had observed fluid spraying from the break.

“The (well) surface safety valve immediately shut the thing down, so it basically just sprayed and stopped,” Rinehart said.

A unified command was activated and a response team proceeded to delineate the extent of the spill. The response team has confirmed that the leak has stopped and that it is safe to work at the site, Rinehart said.

On Dec. 23 Alaska Department of Environmental Conservation environmental program specialist Paul Lhotka told Petroleum News that the response team had delineated the area of the spill, with 14,000 square feet of the gravel well pad, 158,000 square feet of adjacent snow-covered tundra and 50,000 square feet of the drill site’s reserve pit impacted.

The team had removed 72 cubic yards of contaminated snow, primarily from the gravel pad, he said.

The contamination appears to be in the form of oil misting, heaviest near the pipeline rupture and around the well house, with light misting further out.

“It was a wind-driven release, so as you get to the far end of the plume it thins out quite a bit,” Lhotka yet. No pooled spill products have been identified, he said.

The response team has not yet determined the amount of oil spilled and will use two approaches to assess a spill volume, Lhotka said. One approach is to estimate the spill volume from the extent of the surface contamination. The other approach is to use engineering calculations of fluid volumes, using the capacity of the ruptured pipe.

At this stage, the cause of the pipeline failure is unknown and is the subject of investigation.

—Alan Bailey