New Gas Studied in Deaths : Tests: Carbon monoxide is now focus of study in Rincon oil field accident.

Analysts studying tissue and blood samples from three men killed in a Rincon oil rig accident last week said Wednesday they are now focusing on carbon monoxide as the most probable cause of the deaths.

Lab tests on samples taken from the workers who died are due today, but if they do not confirm carbon monoxide as the cause of death, more tests will have to be conducted, Senior Deputy Coroner Jim Wingate said.

“We are not saying these deaths were caused by any specific gas,” he said. “Anything is a possibility at this point. We’re ruling out nothing.”

Early reports from rescue personnel who tried to resuscitate the three men and four others who breathed the deadly fumes indicated that they may have inhaled hydrogen sulfide, a colorless gas that often exists in oil fields.

Since the accident eight days ago, medical examiners have downplayed the probability that hydrogen sulfide killed the oil rig workers because no one at the scene remembers smelling the rotten-egg stench that usually accompanies that gas.

But company officials and state investigators said they have no idea how toxic carbon monoxide could have contaminated the Vintage Petroleum oil field about 10 miles north of Ventura.

“We’re getting a lot of theories from our people,” said John Duncan, who is heading up the investigation by the California Occupational Safety and Health Administration (Cal-OSHA).

Michael Furrow of Pride Petroleum, which employed the three men who died, said there was no visible source of carbon monoxide at the scene of last week’s accident.

“There were no big engines anywhere nearby there, and it would naturally dissipate into the atmosphere anyway,” Furrow said. Nonetheless, he said he does not believe hydrogen sulfide killed the workers.

“When the firemen got there, they recorded just trace amounts of (hydrogen sulfide), when there should have been some very high concentrations,” Furrow said.

“The fact that the other four guys were able to pull the three workers out of the pit (is questionable),” he added. “I’m not sure they would have left (the work pit) if they’d gotten a dose of hydrogen sulfide.”

Chief Medical Examiner Ronald L. O’Halloran said hydrogen sulfide gas is typically the first suspected in an oil field-related accident because it is a poisonous gas known to exist in and around underground crude oil deposits.

But interviews with the four men who survived the fumes and the emergency response crews who arrived on the scene have not yielded the usual evidence, he said.

Hydrogen sulfide and carbon monoxide “seem to be the only two reasonable gases” that could have killed the workers, O’Halloran said.

Tests for hydrogen sulfide already are being conducted at a laboratory out of state, the coroner said.