ANCHORAGE (AP) -- BP Exploration (Alaska) Inc. is dealing with a spill of drilling mud, sea water and rock cuttings at the Prudhoe Bay oil field.
BP officials believe 3,200- to 5,880 gallons of the mixture spewed from a small crack in a pipeline Tuesday.
Most of the material left a gravel pad and spilled onto the snow and tundra, BP spokesman Ronnie Chappell said.
Drilling muds are used to lubricate drill bits. After use, the muds and rock cuttings from the well bore are ground at a Prudhoe Bay facility and then sent through high pressure pipelines to be injected underground.
Tuesday's leak came from a 1-inch crack in a pipeline that carried the material from the grinding facility to an injection well on a nearby gravel pad, Chappell said.
The hole in the pipe was caused by the abrasive material running inside, he said.
State environmental officials said the spill size was about 750 feet wide and a thousand feet long. Traces of the spill extend up to a quarter-mile from the site, officials said.
BP has temporarily closed the Prudhoe drilling mud processing facility, Chappell said.
Oil production has not been affected by the spill, he said.
The mixture was about 85 percent sea water, Chappell said. State spill coordinator Ed Meggert said the mixture also had some toxic materials, including methanol.
The spill is the third significant operational problem for BP this winter.
On Jan. 16, about 18,000 gallons of drilling muds spilled at the Northstar oil development when the wall of a surface containment pen collapsed.
On Feb. 20, up to 9,000 gallons of crude oil spilled when a transportation pipeline ruptured.
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