(i) Petroleum is the next major energy source in India after coal. (ii) Petroleum occurrence in India are associated with anticlines and fault traps in the rock formations of the tertiary age. (iii) About 63 percent of India’s petroleum production is from Mumbai High, 18 percent from Gujarat and 16 percent from Assam. Ankeleswar is the most important oil field of Gujarat while Assam is the oldest oil producing state in India.