Petroleum plays a crucial role in India’s energy landscape, powering vehicles, industries, and domestic needs across the country. Its occurrence in India is a result of complex geological processes that took place millions of years ago. Petroleum deposits are not found everywhere but occur only in specific regions where organic matter was trapped, buried, and transformed under heat and pressure over a long period. In India, the occurrence of petroleum is concentrated in certain basins and sedimentary zones that provide favorable conditions for its formation and accumulation. Understanding where and why petroleum occurs in India is vital for energy planning, exploration, and management of natural resources.
Geological Conditions for Petroleum Formation
Origin of Petroleum
Petroleum is formed from the remains of ancient marine organisms such as plankton and algae. These organisms settled at the bottom of seas and lakes and were buried under layers of sediments. Over millions of years, the organic material underwent chemical and physical changes under high pressure and temperature, forming hydrocarbons, the key components of petroleum and natural gas.
Necessary Conditions
The formation of petroleum requires the following geological conditions
- Presence of rich organic matter in sedimentary basins
- Burial under thick layers of sediment to provide pressure and heat
- Porous and permeable reservoir rocks to hold the petroleum
- Cap rocks or traps to prevent the petroleum from escaping
In India, several sedimentary basins meet these conditions, making them suitable for petroleum occurrence and exploration.
Major Petroleum Reserves in India
Onshore Reserves
India’s onshore petroleum resources are primarily located in the eastern and western parts of the country. The most significant onshore oil fields include
- AssamThis northeastern state was the first region in India where oil was discovered, at Digboi in 1889. Assam’s Upper Assam Basin continues to be one of the most productive petroleum zones in the country, with oilfields at Naharkatia, Moran, and Lakwa.
- GujaratThe Cambay Basin in Gujarat contains important petroleum reserves, including oilfields at Ankleshwar, Kalol, and Mehsana. This basin is known for its productive onshore oil and gas fields.
- RajasthanThe Barmer Basin in western Rajasthan has become a major contributor to India’s crude oil output. The Mangala, Bhagyam, and Aishwarya (MBA) fields are significant discoveries in this region.
Offshore Reserves
Offshore exploration has also revealed rich petroleum reserves along India’s coastlines. Key offshore reserves include
- Bombay HighLocated in the Arabian Sea, about 160 km west of Mumbai, Bombay High is India’s largest offshore oil field. Discovered in the 1970s, it has been a crucial contributor to the country’s oil production.
- KG Basin (Krishna-Godavari Basin)Situated along the eastern coast in the Bay of Bengal, the KG Basin is an important offshore petroleum zone. It contains both oil and gas fields and has seen exploration by both public and private sector companies.
- Cauvery BasinLocated off the southeastern coast, the Cauvery offshore basin contributes to oil and gas production, though on a smaller scale compared to Bombay High or KG Basin.
Petroleum Exploration and Production
Organizations Involved
Several organizations play a role in petroleum exploration and production in India. The key players include
- Oil and Natural Gas Corporation (ONGC)The leading public sector company responsible for onshore and offshore oil exploration and production.
- Oil India Limited (OIL)Another public sector company focusing on oil fields in northeastern India, especially Assam and Arunachal Pradesh.
- Private CompaniesCompanies like Cairn Oil & Gas (part of Vedanta Ltd.) are active in Rajasthan and offshore regions.
Exploration Techniques
Petroleum exploration involves several scientific techniques such as seismic surveys, geological mapping, and exploratory drilling. These methods help locate petroleum reserves below the earth’s surface or seabed. Once a potential reserve is identified, further drilling confirms the presence and volume of recoverable petroleum.
Petroleum Basins in India
Sedimentary Basins
India has 26 sedimentary basins spread over an area of about 3.14 million square kilometers. These basins are classified into three categories based on exploration activity
- Category IBasins with proven commercial productivity (e.g., Cambay, Mumbai Offshore, Assam-Arakan)
- Category IIBasins with identified oil and gas shows but not yet commercially viable (e.g., Kerala-Konkan, Andaman-Nicobar)
- Category IIIBasins with limited exploration and no discoveries yet (e.g., Ganga Basin, Himalayan Foreland)
Prominent Basins
The most petroleum-rich basins in India include
- Assam-Arakan Basin
- Cambay Basin
- Krishna-Godavari Basin
- Bombay Offshore Basin
- Rajasthan (Barmer-Sanchor) Basin
Challenges in Petroleum Production
Geological and Technical Hurdles
Not all discovered reserves are easy to extract. Some lie deep beneath the earth or under challenging offshore conditions. High pressure, difficult terrain, and lack of infrastructure can complicate extraction processes. Additionally, mature fields like Bombay High are experiencing production decline, requiring enhanced oil recovery techniques.
Environmental and Regulatory Issues
Petroleum exploration and drilling can have environmental impacts such as oil spills, habitat disruption, and water contamination. Strict environmental norms and regulatory approvals are necessary before starting any new exploration project. Delays in clearances and local opposition can slow down operations.
Future of Petroleum in India
Domestic Demand
India’s energy demand continues to rise with growing population, urbanization, and industrialization. Petroleum remains a major source of fuel despite efforts to shift toward renewable energy. However, the country still imports a large portion of its crude oil needs, making domestic exploration and production all the more important.
New Discoveries and Policies
The Indian government is encouraging further exploration through policies like the Hydrocarbon Exploration and Licensing Policy (HELP) and the Open Acreage Licensing Program (OALP). These initiatives aim to attract investment and boost domestic production by making the bidding process easier and more transparent.
Shifting Toward a Balanced Energy Mix
While petroleum will continue to play a role in India’s energy mix, the future also involves gradual diversification. Natural gas, biofuels, solar, wind, and hydrogen are gaining attention as part of India’s transition to cleaner and more sustainable energy sources.
The occurrence of petroleum in India is closely linked to its geological history and the presence of favorable sedimentary basins. From the oil-rich lands of Assam to the deep waters of the Arabian Sea and Bay of Bengal, petroleum plays a vital role in powering India’s economy. Continued exploration, investment in technology, and responsible management of resources are key to ensuring that India meets its future energy needs while balancing sustainability and growth.