New Delhi: Oil and Natural Gas Corporation (ONGC) is unable to exploit the block in the Krishna-Godavari (KG) Basin off the Andhra Pradesh coast, where it has made its biggest gas discovery due to non-availability of rigs.

The gas find in ultra deepwater well in KG Basin became controversial when the Directorate-General of Hydrocarbons (DGH) discounted it on grounds that ONGC had not followed the conventional method of testing to establish the find and abandoned the well.

Subsequently, while accepting the discovery, the DGH had said that if ONGC makes a re-entry in the well located in KG-DW-98/2 block and carries out the required tests, discovery or potential commercial viability could be accepted.

ONGC holds 90 per cent interest in the KG block, with rest being held by Cairn.

The company said it does not plan to re-enter the ultra deepwater well (UD1) where it has found hydrocarbons and may undertake conventional testing for one of the appraisal wells in the block, as the feature of the area is very large.

This would be subject to availability of rigs. The company''s rigs however are already deployed in other blocks.

There is an acute shortage of such rigs worldwide, and apart from spiralling of charter rates most of the rigs are overbooked.