Prior to 1976 entire production of crude oil in the country was obtained from onshore areas. But gradually the contribution of offshore areas increased up to 67% (1997-98). In recent year the declining production in Bombay High has led to decreasing production of crude oil in the country.
(a) Bombay High Oil-field-this is the largest oil producing area contributing over sixty per cent of the total crude oil output of the country. The area is estimated to possess about 330 million tons of oil and 37,000 million cubic meters of natural gas. Oil bearing strata consist of limestone rocks of Miocene period at a depth of 80 m. The Bombay High covers an area of 2,500 sq. km and lies about 176 km southwest of Mumbai. Although oil was discovered in this area in 1973 but commercial production began in 1976. This enabled India to achieve self sufficiency and reduce the burden of oil import. But due to over exploitation the output is declining since 1991.
Efforts are being made to exploit LII, LIII and Neelam oil-fields to augment production and to adopt certificatory measures to increase pressure in oil wells through water injection. The Bombay High crude contains higher percentage of petrol and kerosene but lacks sculpture content.
(b) Bassein Oil-field-this oil-field lies south of the Bombay High. Here oil occurs at a depth of 1,900 m and structure is smaller in size. Oil reserves are larger than the Bombay High.
India is not self-sufficient in respect of crude oil and petroleum based products. Hence every year it has to import huge quantity of these products from abroad highlights rapid increase in the quantity and value of petroleum and its products imported from foreign countries.
Although country’s reliance on foreign import has decreased due to rise in domestic production but the net quantity and value of import have not gone down due to rapid growth of population and increasing demand of oil and petroleum products in transport, industry and other sectors of economy.
In 1960-61 India had to fulfill over 90% of its petroleum needs through import. It came down to 66% in 1965-66, and in 1985-86 due to rapid increase in domestic production. Since then the gap between domestic demand and consumption is gradually increasing and presently the country has to meet 55% of its demands of petroleum and petroleum products through import. This import mainly can from Middle East (Iraq, Iran, Kuwait, Saudi Arabia, Baherin), Russia, Kazakhstan, Indonesia and Malaysia.
India imported 8 lakh tones of petroleum, and lubricant products worth of 690 million rupees in 1960-61. This increased to 23.54 million tons valued at Rs. 5,264 crores in 1980-81 and 54.1 million tons valued at Rs. 35,629 crores in 1996- 97. There has been about 68 times increase in the quantity and 516 times increase in the value of imported petroleum and petroleum products between 1960-61 and 1996-97.
This is due to excessive increase in the price of crude of petroleum products in the international market the petroleum exporting countries. This has plain adverse effect on the economy of developing countries like India which had to utilise a major parotid export earning on the import of crude petroleum if goods. In 1970-71 India spent only 8.9%ofitsexpo earning on the import of petroleum products but this burden increased to between 1980-81 and 1986-87. Presently this percentage share is 29 which are also abnormally in view of the unsound position of the Indi economy.
(c) Aliabet oil-field-Aliabct oil-field is situated 45 km from Bhavnagar in the Gulf of Cambay.
(4) Eastern Coast Oil-fields
This includes discovery of petroleum and natural gas in the basin and delta regions of the Godavari, Krishna and Kaveri rivers. Hence, these are onshore and offshore areas where exploration works have been recently carricd on. The Rawa field in the Krishna-Godavari offshore basin is expected to contribute 1 to 3 million tons of crude oil annually. The oil field near Amlapur (A.P.) is expected to yield 3,600 barrels of crude oil per day. The Narimanam and Koirlkalaapalli oil fields in the Kaveri onshore basin are yielding about 4 lakh tones of crude oil annually. A five lakh tone refinery has been set up at Panaigudi near Chennai to refine crude from this area.
Reserves of crude oil have also been discovered in the deltaic tract of the Kaveri River, Bilaspur tahsil of Rampur district (Uttar Pradesh), Jwalamukhi area in Punjab and desert area in Rajasthan. Oil has been discovered in Bhagyam and Vijava oilfields near Banner (Rajasthan) at a depth of 1,900 m. This will produce about 2,000 barrels of crude oil per day.