Under fire for its activities in the Cauvery basin, the State explorer Oil and Natural Gas Corporation has said that it is only making an assessment of the potential of shale gas — natural gas usually found in compact low-permeability rocks beneath the surface.

Addressing the media here on Thursday, AK Dwivedi, Director of exploration, ONGC, explained that the corporation was not exploring shale gas or coal bed methane in Tamil Nadu, adding that there was no official policy on exploration of shale gas in India.

“We do not have any ongoing shale gas project in Tamil Nadu. The Union government has entrusted ONGC with the job of carrying out research and development for exploring and assessing the potential of shale gas. We are continuing with research and development work in Kuthalam,” Dwivedi said.

“Only when we assess the potential we will come out with a policy,” he added.

The state-run corporation has been facing flak from farmers, environment activists and political parties for its work in Kuthalam in Cauvery, which opponents allege would affect agriculture in the basin, the rice bowl of Tamil Nadu. The case reached the Southern Bench of the National Green Tribunal here in Chennai, which restrained the corporation and Gas Authority of India Limited from extracting methane as alleged by the petitioner.

“The stay was vacated after we clarified that we had been conducting seismic surveys for acquiring data for oil and gas exploration. They are not at all related to methane gas extraction,” he said.

ONGC is awaiting clearance from the Union Environment Ministry to begin drilling at Kuthalam. “As and when it is received, the State government will be approached for further clearances,” Dwivedi added.

The official added that ONGC was not planning to use hydro fracturing, popularly known as fracking, a process in which a large quantity of water, sand and chemicals are pumped underground to break apart the rock and release the gas. Though effective, this process has its share of opponents who point out that fracking is harmful for the environment.”

“We are in need of technology that doesn’t use water,” he said, adding: “We may be going in for sound waves or other energy resource,” he said.

On the potential for fossil fuels in Tamil Nadu, he said the state had a capacity of 82,000 million tonnes of reserves and only 20,000 million tonnes was tapped. The remaining 60,000 million tonnes was yet to be exploited, he said. There were 31 oil and gas fields in Tamil Nadu, producing 700 tonnes of oil and about 3.2 million cubic metres of natural gas per day, he said.

ONGC was providing 50 per cent of gas to the state electricity board. “This is being used to generate 650 to 700 MW power,” he said.