RIL and its partner BP plc of UK encountered 155 metres of gas pay zone in the first exploration well drilled on the block in more than five years. The well was drilled two kilometres below the existing producing D1&D3 fields.
"The KGD6-MJ1 well was drilled in a water depth of 1,024 metres - and to a total depth of 4,509 metres (4.5 kilometres below seabed)," RIL-BP said in a statement.
The well was drilled to explore the prospectivity of a Mesozoic Synrift Clastic reservoir lying over 2,000 metres below the already producing reservoirs in the Dhirubhai-1 and 3 (D1&D3) gas fields.
"Formation evaluation indicates a gross gas and condensate column in the well of about 155 metres in the Mesozoic reservoirs," the statement said adding the well flowed 30.6 million standard cubic feet per day of gas during testing.
Though RIL-BP did not put any reserves to the discovery, the find may possibly be the largest single discovery in the country. The discovery, which was notified to the regulatory authorities this afternoon, has been named D-55.
Sources said the resource found may be significantly more than a pre-drill best case gross prospective resource of 819 billion cubic feet of gas and 56 million barrels of liquids for the well.
RIL-BP had drilled MJ-1 well in early March after the government permitted companies to drill exploration wells in areas where exploration period had long expired.
Dhirubhai-1 and 3 (D1&D3) gas fields, the largest among the 18 gas finds on KG-D6 block, have proved to be more difficult to produce than previously predicted.
D1&D3 reservoir has seen sharper-than-expected drop in pressure and water and sand ingress in production wells, leading to a drop in output.