New Delhi, Jan. 3: ONGC is expected to make a formal announcement of its gas strike in the deep water Krishna-Godavari basin within this month.

The PSU is not giving an estimate of the reserves as this is not possible on the basis of the results from a single exploratory well.

The announcement of the other big find in the shallow waters of the eastern offshore Mahanadi basin will be made a few days later.

ONGC chairman R.S. Sharma, back from the two sites, said: “I am satisfied with the pace of work that is going on in both the exploration blocks … since ONGC is a listed company all announcements related to new discoveries will be made according to the due procedure. The company believes in following good corporate practices and all official norms will be observed in declaring the finds.”

Sharma said the data would be certified by the directorate general of hydrocarbons.

Senior ONGC officials said that “based purely on the seismic data, the ONGC KG-DWN-98/2 block could turn out to be bigger than even the giant Reliance gas field.”

“However, such a generalisation is based on the fact that the high yield shown by the exploratory well is extrapolated to the entire block,” they explained.

The officials said at least seven to eight wells will have to be spudded before an accurate estimate of the in-place gas reserves can be made. “We are keeping our fingers crossed and hoping for the best,” a senior official said.

“It could take several months to arrive at a realistic estimate of the reserves,” a senior official said.

ONGC holds 90 per cent operating interest in the KG basin block. The stake was acquired from Cairn India, which now has a 10 per cent stake.

According to sources, the test reports of the first well in KG basin confirmed a 30-metre gas pay zone at a depth of 5,300 metres in the seabed.

According to sources, the reserve size may increase further as seismic studies of the well indicate presence of another 80 metre pay zone at 6,450 metres. This could work out to a gas potential of 25 trillion cubic feet, by generalising this find to the rest of the seismic data.

In addition to the KG basin strike, logging reports from the MN-OSN-2000/2 block suggest that the company has struck a gas reserve in the Mahanadi basin opening up opportunities of future strikes in the block.