Down is Up as Aging Oil Fields Defy Gravity to Pump More Crude

Bob Dudley, in his 38 years in the oil industry, has never seen anything like what happened with BP Plc’s old fields last year: They gushed more crude.

“I cannot remember ever in my career having seen a negative decline rate,” the British oil-giant’s chief executive officer said in an interview on the sidelines of the CERAWeek by IHS Markit energy conference in Houston.

The fact that Dudley isn’t alone in seeing mature fields dwindling less than expected—and in BP’s case surprisingly increasing—means the Organization of Petroleum Exporting Countries has one more thing to worry about. As if the ...