Nigeria’s two oil unions began an indefinite strike that they say will curb exports from the West African nation responsible for pumping more than a quarter of the continent’s crude. “You will soon begin to see shutdowns of our oil flow,” Emmanuel Ojugbana, a spokesman of the Petroleum and Natural Gas Senior Staff Association of Nigeria, said by phone. Ohi Alegbe, an Abuja-based spokesman for the Nigerian National Petroleum Corp. and the Oil Ministry, declined to comment on exports. Any reduction in pumping would coincide with a collapse in the price of Nigeria’s biggest source of revenue. Brent crude oil plunged 44 percent this year. It rose as much as 2.3 percent to $63.25 a barrel in London today. Nigeria needs about twice that to balance its budget, according to estimates in October from Deutsche Bank AG. “We do not expect the strike to have a material impact on […]