First the U.S. shale-oil boom took away Nigeria ’s biggest crude-export market. Now Africa ’s biggest economy is depending on American fuel to power its vehicles and planes. The CHART OF THE DAY shows how U.S. imports of Nigerian crude have almost converged with American sales of refined-petroleum cargoes like gasoline and kerosene shipped in the opposite direction. The U.S. gets less than 2 percent of its oil from Nigeria, compared with 7 percent in 2011, Energy Department data show. Nigeria imported more than half of its fuels from America at times in 2013, from less than a fifth three years ago, according to IHS Inc., a consulting firm. Surging oil output in the U.S., most of it banned from export under decades-old laws, hands refiners on the Gulf Coast inexpensive feedstock to process into cargoes such as gasoline for sale overseas. Nigeria’s growing dependence highlights its […]