EOL also told the ministry officials that tender for 3D seismic survey on contract basis over an area of about 70 square km, as per the PSC, is finalised and will be released shortly.

"This area also holds good potential for exploration for coal bed methane. Essar Oil had earlier drilled a few exploratory wells and has established the methane gas deposit. Essar will also commence coal bed methane extraction after receiving all the necessary approvals," a company source said.

In addition, Essar also has other four exploration blocks. Recently, the ministry of petroleum and natural gas has cleared the way for signing of the PSC for Ratna and R series oil field.

The signing of the PSC is subject to compliance of standard terms by Essar Oil. The initial oil in place of all these fields is about 500 million barrel.

"The recoverable reserves are estimated at 100 million barrels, of which 10 million barrels have already been recovered by ONGC. The work programme at Ratna envisages drilling over 30 wells through the installation of four platforms and modifications in the existing Ratna A platform," the source said.