Oil pricing strategy in india

Oil refinery done domestically make oil cheaper in india but companies still sell them on international rates increAsing their profit margins.
India import around 55 million barrels of crude oil per month, refines it into range of products varying from kerosene, naptha, diesel to petroleum. India doesn't import petroleum. Refineries export mainly diesel, naptha and petroleum. Now Custom duty apart from insurance and freight cost is added to the petroleum to be exported. This custom duty actually determines the gross refining margin. Indian consumers bear this margin of custom duty which is enjoyed by the refineries. This is because the price at which petroleum is sold in india is same as the price with which these refineries sell petroleum abroad. For example, if the crude oil is of cost x and refinery cost is Rs 100, then this x+100 is not the final price of the oil. Assuming custom duty to be Rs 100 then the final price becomes x+200. This shows that indian refineries can be twice as inefficient as an international refinery. Actually the main purpose of custom duty is mainly to encourage that sector of industry apart from an obvious source of income for the govt. But since India doesn't import petroleum or diesel so removing custom duty will not effect govt's revenue thru custom. Moreover as far as eencouraging the refinery sector 's concerned, its not required anymore as decades of protection and being major exporters the indian refineries are alreasy in a very stable condition with best minds with them. So the quetion remains does these custom duties required AT ALL?? The obvious answer seems to be NO. Moreover it will make the Indian Refinereies all the more efficient and competative when they will have to compete with Intl Refineries.