Oklahoma has 20 percent more rigs in active service than North Dakota as shale activity in the United States evolves, state data show. XTO Energy, a subsidiary of Exxon Mobil, is the largest operator of active wells in North Dakota, with 14 percent of the 86 active wells in the state at the heart of the nation’s oil boom. Overall, the number of rigs in service in North Dakota is down 7.5 percent since the start of April. Last year, XTO said it owned 531,000 net acres in North Dakota and gross production in February 2014 was 44,516 barrels of oil per day. Federal data show state oil production in February 2014 was 953,000 bpd, about 24 […]