. >> eva rowe's parents were among the 15 who died that day in texas city.worst workplace accident in this country in 16 years. >> these things do not have to happen. they are preventable. they're predictable, and people do not have to die because they're earning a living. >> welcome to 60 minutes on cnbc. i'm leslie stahl. oil is the engine that drives our economy. and as oil becomes scarcer, the push to discover and develop new sources becomes increasingly dangerous. this edition examines two recent disasters in the oil industry with a great deal in common: the deepwater horizon rig in the gulf of mexico and the refinery at texas city, which suffered explosions five years apart. they were both operated by bp. and in both cases, 60 minutes looked at whether bp's cost saving measures may have had deadly consequences. first we'll look at the biggest off shore oil spill in history, the blowout of the deepwater horizon drilling rig in 2010. critical revelations in the disaster have come from one of the last crewmen to escape the rig, mike williams, who first to