"The Directorate General of Hydrocarbons has approved our appraisal plan for the gas discoveries in deep-sea block KG-DWN-98/2. We plan to drill six appraisal wells to assess the potential and delineate the discoveries," a company official said.

The block sits next to Reliance Industries prolific KG-DWN-98/3 or D6 block. ONGC plans to tie up 10 discoveries in KG-DWN-98/2 with the G-29, GS-4 and Vashistha gas finds in a shallow water block KG-OS-DW4 in the same basin.

Besides natural gas, ONGC also plans to produce 8,000 barrels of oil per day from the fields. The reserve estimates and production plan in ONGC's appraisal programme, however, excludes ultra-deepwater UD-1 discovery in KG-DWN-98/2 block.

The UD-1 discovery alone has been certified by DGH to hold just over 2 Trillion cubic feet of inplace gas reserves.

Ten discoveries in KG-DWN-98/2 (excluding UD-1) and three in adjacent block together hold 6.37 Tcf of inplace reserves.

Without UD-1, the block is assessed to hold just over 5 Tcf of inplace gas reserves.

ONGC has roped in Statoil of Norway and Petrobras of Brazil as equity partners in the KG-DWN-98/2. Statoil and Cairn India hold 10 per cent each in the block and Petrobras 15 per cent, while ONGC has the remaining.