Cairn Energy's KG-DWN-98/2 block has confirmed reserves of around one trillion cubic feet.

Although final tests are still being conducted to ascertain the exact quantity of gas - and an exploratory well is being drilled to a target depth of around 2,500 m - ONGC's private sector rival Reliance, who also discovered gas in the area, believes that ONGC is sitting on about 14 trillion cubic feet.

Officially, ONGC will not comment on the exact size of the discovery, but its officials have insisted the well is "a commercial discovery and [has] brightened the prospects of further gas finds in the region, making it probably the biggest gas-bearing basin in the country". ONGC currently operates 12 blocks in the area.