Potential oil-bearing area extends over 10 lakh 700 km. in India ; (almost 1/3rd of area of the country). It includes the Ganges-Brahmputra plain, coastal belts, Gujarat plains, Thar Desert and Andaman Nicobar inlands.

Position at the time of Independence. At the time of independence, oil was found only in Assam. Oil refinery was set up at Digboi. It was a small oilfield. But it worked for about 100 years.

Oil-exploration after the independence. Oil exploration was started to meet the growing demand. Oil and natural gas was discovered in off-shore regions of Gujarat and Gulf of Cambay. Oil was found at Bombay (Mumbai) High at a distance of 115 kms from Mumbai coast. At present, it is the largest oilfield of India. A mobile drilling platform ‘Sagar Samrat’ from Japan was used to explore oil. India extended this oil region. New oilfields have been discovered in off-shore regions of deltas of Mahanadi, Godavari, Krishna, Cauvery. New oil reserves have been found in Assam.