Nigeria’s crude oil production rose by 200,000 barrels a day to 2.15 million in June, a Bloomberg survey of Organization of Petroleum Exporting Countries (OPEC) producers shows. The gain in Nigeria was the second-biggest in the survey and the highest output since September. Figures for Africa’s biggest producer are volatile because of unrest and theft in the Niger River Delta, the main oil-production region. Production by the 12-member OPEC rose by 278,000 barrels a day to 30,223 million, according to the survey of oil companies, producers and analysts.