Mahanadi Basin: ONGC’s First Deepwater Well Under Samudra Manthan

30 July 20261 min read

Why in the news

ONGC kicked off deepwater drilling off the Odisha coast, linking the river’s old sediment deposits with the hunt for hydrocarbons.

Well: MN-DW18-1-H-D, spudded on 25 July 2026.
Mission: Samudra Manthan (National Deep Water Exploration Mission).
Plan: first of four deepwater wells in the basin.
Offshore opening: almost one million sq km of barred offshore area opened for exploration.

Name means “Great River”; largest river of Odisha, heavy silt, wide delta.
Source: Sihawa range, Dhamtari district, Chhattisgarh; flows north, then east into Odisha.
Cuts the Eastern Ghats at Satkosia Gorge (a Tiger Reserve); ends in the Bay of Bengal at False Point.
Basin states: Chhattisgarh and Odisha, plus small parts of MP, Jharkhand and Maharashtra.

Left bank	Right bank
Seonath (Shivnath), the longest	Jonk
Hasdeo	Ong
Mand	Tel, the largest on the right bank
Ib

Past river discharge laid down thick sediments offshore, a key condition for hydrocarbons.
It is a Category II/III sedimentary basin.

Created DeepX, a deepwater exploration centre, in Mumbai on 5 January 2026 on a “One Company, One Data” idea.
Builds on earlier Utkal and Konark finds.

Static facts: Seonath is the longest tributary; Tel is the largest right-bank tributary.
Centre: DeepX, Mumbai, 5 January 2026.

Test yourself

1. Where does the Mahanadi river originate?

The notes say it rises in the Sihawa range of Dhamtari district, Chhattisgarh.

2. ONGC's first deepwater exploratory well MN-DW18-1-H-D lies in which basin?

It is in the Mahanadi Offshore Basin.

3. Which is the longest tributary of the Mahanadi?

Seonath is listed as the longest tributary.