Deposits of Coal and Petroleum in India | Geology Optional Notes for UPSC PDF Download

Coal - Indian Occurrences

• India is among the top five global coal producers.
• The country possesses vast reserves of common or bituminous coal, primarily non-coking in nature.
• Major coalfields in India are located in the Damodar, Mahanadi, Godavari, and Son-Narmada valleys.
• Indian coal deposits are categorized into two groups based on their geological age: Gondwana Coals and Tertiary Coals.

Gondwana Coals Overview

• Gondwana Coals in India: Approximately 98% of India's annual coal production originates from the Lower Gondwana sequence, which dates back 200 million years to the Permian age.
• Coal Types: The Lower Gondwana coals primarily belong to the bituminous type.
• Major Coalfields:
  • Jharia Coalfield, Jharkhand: Located in Dhanbad District, this coalfield is crucial for India, supplying around 50% of the nation's coking coal.
  • Bokaro Coalfield, Jharkhand: Spanning 65 km east to west and 10 to 16 km north to south in Bokaro District, it boasts some of the thickest coal seams, mainly bituminous coking coal.
  • Raniganj Coalfields, West Bengal and Jharkhand: Among the largest in India, with most coalfields in the Raniganj area in Burdwan district, West Bengal, extending into Jharkhand. Known for high moisture and volatile content.
  • Singrauli Coalfield, Madhya Pradesh: A significant coalfield spread over Madhya Pradesh and Chhattisgarh, containing various coal seams ranging from non-coking high-grade to moisture-rich inferior grade coals.
  • Talcher Coalfield, Odisha: The primary coalfield in Odisha, located in Angul District, covering over 500 sq. km. Known for its low-grade non-coking coal.
  • Rajmahal Coalfield, Jharkhand: Situated along the western side of the Rajmahal Hills, extending from the north to Birbhum District, West Bengal.
  • Wardha Valley Coalfield, Maharashtra: Located in the Wardha Valley of Maharashtra.

Tertiary Coals

• Tertiary coals are primarily located in various states such as Assam, Meghalaya, Nagaland, Arunachal Pradesh, Himachal Pradesh, West Bengal, Rajasthan, Kerala, and Jammu and Kashmir. Additionally, Tamil Nadu and the Union Territory of Pondicherry also possess reserves of Tertiary coal.
• These coals are characterized by having low carbon content along with high levels of moisture and sulphur.
• Assam's Tertiary coal reserves are distributed in regions like Makum, Nazira, Mikir Hills, Dilli-Jeypore, and Lakhuni. Notably, Assam's coal exhibits low ash content but high sulphur levels, making it unsuitable for metallurgical purposes due to its high coking qualities.
• The Makum coalfield in Tinsukia district is the most developed within Assam.
• In Meghalaya, coal deposits are concentrated in the Khasi Jaintia and Mikir hills regions.
• Jammu and Kashmir house Tertiary coal in areas like Kalakot and the surrounding regions south of Pir Panjal.
• Himachal Pradesh also has coal reserves located in Chamba district.

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Petroleum in India

• India, like many other countries, faces a deficit in oil production and heavily relies on imports to fulfill its demand.
• There are 26 sedimentary basins in India that have been identified as having petroleum potential.
• In Assam, significant oil reserves are present, with extraction taking place in oil fields such as Digboi, Naharkatiya, Moran, Rudrasagar, and Lakwa.
• Western India boasts notable oil fields including Ankleshwar in Gujarat, Mumbai High (offshore Arabian Sea) in Maharashtra, Cambay, and Kalol.
• Promising oil fields are also located in states like Arunachal Pradesh, Tripura, Nagaland, Andhra Pradesh, and West Bengal.

Important Oil Fields

• Digboi Oilfield:
  • Location: Situated in the northeastern part of India, in the Naga Hills area of the Tinsukia District.
  • Characteristics: Occupies a 13sq km area and is located in an anticlinal trap.
  • Example: Oil is extracted from reservoirs that are folded and trapped in geological formations.
• Cambay Oilfield:
  • Location: Positioned north of the Gulf of Cambay in Gujarat, around 8km northwest of Cambay city.
  • Geological Formation: Oil deposits are found in rocks dating back to the Oligocene age.
  • Significance: Offshore oil occurrences have been noted in the Arabian Sea region.
• Ankleshwar Oilfield:
  • Location: Situated south of the Narmada river, approximately 81km SSW of Baroda.
  • Geological Features: Oil-producing sands belong to the Eocene age and are located on an elongated doubly plunging anticline and dome.
  • Illustration: The oil reservoirs are found in folded rock structures, forming traps for oil accumulation.
• Coastal Oilfield:
  • Location: Extends along the East Coast of Peninsular India, covering areas like Andhra Pradesh, Tamil Nadu, and Orissa.
  • Source of Oil: Oil is derived from marine sediments of Cretaceous and Tertiary ages.
  • Explanation: The oil is extracted from ancient seabed deposits that have undergone geological transformations over millions of years.