With U.S. sanctions blocking Venezuela from selling oil to the United States, state-owned energy firm PDVSA has turned to several little-known buyers that include a tiny Turkish company with no refineries but ties to President Nicolas Maduro’s government, according to internal documents and a PDVSA source. Until recently, some of the world’s largest petroleum and refining firms, including U.S. companies Chevron and Valero Energy, lined up to take Venezuelan oil cargoes and PDVSA had a rigorous vetting process to ensure potential buyers had the capacity to pay. But U.S. sanctions imposed in January in an effort to oust Maduro have driven away many of those customers. PDVSA’s exports have slumped by more than a fifth since sanctions were […]