Crews Try to Contain Five-Mile Slick : Spills: Wind and currents have kept oil from ruptured pipeline away from environmentally sensitive areas.

Cleanup crews attacked a five-mile oil slick off the Ventura County coast Saturday in the second day of efforts to contain 420 to 2,100 gallons of crude oil that spilled when a work boat ripped open an offshore oil pipeline.

Working in shifts around the clock, crews aboard 11 boats unfurled hundreds of feet of floating booms to contain the slick about six miles off ecologically sensitive wildlife habitats on Anacapa Island and Mugu Lagoon on the mainland.

Unocal officials said they still could not predict whether the oil that leaked from Unocal’s Platform Gina would reach land. They said they hoped to have most of the heavy oil skimmed from the surface in a few days.

“The slick appears to be moving parallel to the shore,” said Brian W.G. Marcotte, a Unocal vice president. “It all depends on where the wind and the currents take it.”

Unocal has taken responsibility for the relatively small spill that occurred about 2 p.m. Friday when a work boat severed a 10-inch pipeline that carries 1,250 barrels of oil a day from the platform to shore.

The boat was dragging a grappling hook to retrieve an anchor chain near the platform. The 197-foot boat snagged the pipeline about 200 yards from the platform and pulled on it until it snapped on one of the platform’s legs, Unocal officials said. Automatic sensors quickly shut off the pipeline’s pumps.

The U.S. Minerals Management Service, which oversees oil leasing in federal waters, is investigating the incident. An agency spokeswoman said she would have no comment on the investigation until it is completed.

“This is a minor spill, but we have a couple of very sensitive habitats in the Channel Islands and Mugu Lagoon,” said Lt. Reed Smith of the California Department of Fish and Game. “There is going to be some damage. It just depends on how long the oil stays on the surface.”

Thomas W. Keeney, a Navy ecologist, said he and his colleagues have walked most of the shore near Point Mugu Naval Air Station and found no oil-soaked birds. “We’re just praying that the wind stays in our favor.”