A massive fire has erupted at a crude oil upgrader project in Venezuela after an explosion was heard near the distillation tower, workers on site and sources at state oil firm PDVSA told Reuters. The Petrocedeno project in Venezuela’s Orinoco Belt, operational since 2000, was one of the four original projects in the heavy crude oil belt in the world’s biggest holder of crude resources. Petrocedeno, operated by PDVSA, extracts extra-heavy oil and upgrades it into a lighter synthetic crude for export. Petrocedeno produces…