Parker Waldridge had worked in the Oklahoma oilfields since he was 16 and acquired the traits that make a good driller: fortitude, intellect and a healthy respect for the power of a runaway gas well. And so, when Waldridge’s wife, Dianna, heard there had been an accident on a rig he was working near Quinton, in the southeastern corner of the state, last Jan. 22, she tried to stay calm. Parker, an independent contractor hired as a well site consultant, was obsessed with safety and had not once expressed fear about a job during their 34-year marriage, she told herself. Still, on the four-hour drive to Quinton from their home in Crescent, north of Oklahoma City, dread began to creep in. Dianna had learned before leaving that Parker was among five men missing after an explosion on Patterson Rig 219, operated by Houston-based Patterson-UTI. At a church in Quinton, she sat with her four grown daughters, a son-in-law and the other workers’ families, awaiting confirmation of what everyone there suspected: the men weren’t coming back. They would have to be identified through dental records. Drilling is an inherently dangerous undertaking, with a fatality rate nearly five times that of al...