ONGC- discovered natural gas reserves- Mahanadi basin

The state-owned Oil and Natural Gas Corporation (ONGC) (It is an Indian oil and gas explorer and producer.It is under the ownership of Ministry of Petroleum and Natural Gas, Government of India. Its headquarters is situated in New Delhi. ONGC was founded on 14 August 1956 by the government of India. It was conferred with 'Maharatna' status by the Government of India in November 2010) recently discovered two significant natural gas reserves in the Mahanadi basin block in the Bay of Bengal.

Mahanadi River Basin

• It is the 8th largest river basin in the country, with a total catchment area of 139681.51 sq. km, which is nearly 4.28% of the total geographical area of the country.
• The catchment area of the basin extends over major parts of Chhattisgarh and Odisha and comparatively smaller portions of Jharkhand, Maharashtra, and Madhya Pradesh.
• It is bounded by the Central India hills on the north, by the Eastern Ghats on the south and east, and by the Maikala range on the west. 

Mahanadi River

• It is one of the major east-flowing peninsular rivers in India.
• Origin: The river originates from the Sihawa range of hills in the Dhamtari district of Chhattisgarh state.
• It ranks second to the Godavari River among the peninsular rivers in respect of water potential.
• The total length of the river form origin to its outfall into Bay of Bengal is 851 km of which 357 km lies in Chhattisgarh and 494 km in Odisha.
• Tributaries: The Seonath, the Hasdeo, the Mand, and the Ib join Mahanadi from left, whereas the Ong, the Tel, and the Jonk join it from right. 
• Hirakud Dam: The Hirakud Dam, the world's longest earthen dam (26km), is constructed across the Mahanadi River, about 15 km from Sambalpur in Odisha.
• Chilika Lake: Chilika, named wetland of international importance under the Ramsar Convention, gets 61% of its inland flow from the Mahanadi River system, mainly from its distributaries, Daya and Bhargabi.