Russia’s Ryazan oil refinery—its fourth-largest and a key Rosneft asset southeast of Moscow—was forced to halt a major crude distillation unit after a Ukrainian drone attack set part of the facility ablaze this week, industry sources told Reuters. The targeted unit, CDU-4, handles roughly 4 million metric tons of crude per year, or about 80,000 bpd—nearly a quarter of the refinery’s total capacity. The stoppage, combined with secondary unit shutdowns including a reformer, vacuum gasoil hydrotreater, and catalytic cracker,…