The discovery was made in the west Tripura block in the Assam and Assam Arakan basin, the company said. Exploratory well Sundalbari-4 was drilled to a depth of 3,400 meters and flowed gas at the rate of 160,000 cubic meters per day.
The gas contains upto 96.3 per cent methane, ONGC said, but did not give any estimates of potential reserves in the new discovery.
"This is a new pool discovery in Upper Bhuban Formation in a separate fault closure. This discovery has opened up a new reservoir for further exploration within the Sundalbari area and has also proved the extension of the field as a whole," the statement said.
According to another report, the company declared on Friday that it plans to invest Rs 8,554 crore (Rs 85.54 billion) in western offshore fields by 2012.