By Ben Aris in Berlin Since the beginning of the year, Ukrainian drones have attacked over two dozen Russian oil refineries and several oil depots in the first sustained campaign against Russia’s oil product producing facilities, with half the attacks successfully causing damage and delays. Russia still has plenty of spare capacity. Russia’s refining throughput is 5.5mn barrels per day (bpd), while domestic consumption is less than half of that. The country produces twice as much diesel as it needs and is a major exporter of the fuel, while the gasoline surplus capacity before the attacks was …