Reliance had won the block in the third round of auction under New Exploration Licensing Policy, where it holds 100 per cent interest after Hardy Oil of UK relinquished its 10 per cent stake.
Gas reserves were found in well A-1, the first well on the block CY-DWN-2001/2, drilled by Transocean's drillship Deepwater Frontier, the officials said.
While Deepwater Frontier has moved to develop Reliance Industries' gas finds in the prolific KG-D6 block in Krishna Godavari basin, off the Andhra coast, Transocean's another drillship Actina is currently drilling a second well on the 14,325 sq km block.
The Mukesh Ambani-run company plans to start producing next year 80 million cubic meters of gas a day from KG-D6, which was discovered in 2002. The CY-DWN-2001/2 block was awarded to Reliance Industries (90 per cent) and Hardy Exploration (10 per cent) in February 2003.
Subsequently, RIL took over Hardy's interest in the block. The company has committed to shoot 2,100-km of 2D, 1,650 sq km of 3D and drilling of three exploratory wells in the four-year Phase-I of its exploration programme on the block.
In the two-year phase-II work programme, Reliance would drill four exploratory wells and in the two-year phase-III work programme, the company would drill another four exploratory wells.
