New Delhi: Indian Oil Corporation (IOC), the nation’s top oil firm, on Tuesday said it will invest Rs 17,825 crore in raising the capacity of its Gujarat refinery as well as setting up a petrochemical plant at the unit as part of plans for upscaling petrochemical business to protect margins. In a regulatory filing, IOC NSE -0.53 % said its board at a meeting on September 21 “accorded approval for implementation of petrochemical and lube integration project at Gujarat refinery at an estimated cost of Rs 17,825 crore”.