Drillers that unlocked the shale oil boom in the U.S. are finding it hard to shut off the nozzle. U.S. crude production rose even as prices slumped to the lowest in more than five years and the number of rigs targeting oil decreased. In North Dakota’s prolific Bakken shale formation, output rose in November as the number of new wells coming online fell by 73 percent. The increases illustrate how improvements in horizontal drilling and hydraulic fracturing technology may prop up U.S. crude production even as companies cut spending, idle rigs and lay off thousands of workers with oil prices down more than 50 percent since June. “We have an oversupply of crude,” Michael Hiley, head of energy OTC at LPS Partners Inc. in New York , said yesterday. “Production keeps going up. There is not a great correlation between the rig count and production because drilling has gotten […]