sentences:  On Jan 30th 2018, Oil & Natural Gas Corporation acquired the entire 51.11% stake of Hindustan Petroleum Corporation.Before the independence of India in 1947, the Assam Oil Company in the north-eastern and Attock Oil company in the north-western part of the undivided India were the only oil-producing companies, with minimal exploration input.The major part of Indian sedimentary basins was deemed to be unfit for the development of oil and gas resources.