Experts Hint At Possible Existence Of Gas Fields West Bengal

Kolkata: In a finding that could somewhat ease the country’s energy security concerns, an eminent geologist who has extensively worked in the eastern part of India has said that there is a high possibility of the existence of hydrocarbons in the West Bengal basin.

According to Naresh Ghose, a retired professor of Geology of Patna University, specific indication for this is based upon his studies on the ‘Rajmahal basalts’ in Jharkhand, adjoining the West Bengal basin.

Basalts are volcanic rocks and the Rajmahal basalts form a part of the gigantic flood basalt province that erupted at the Eastern Indian Shield about 120 million years ago. The eruption coincided with the global events of crustal extension accompanying the breaking away of the ‘Gondwana’ supercontinent, formation of the Indian Ocean and separation of the Indian shield from Western Australia and Eastern Antarctica.

The exposed lava flows currently occupy an area of 4,300 sq. km. in Jharkhand, Ghose told this correspondent in an e-mail. The presence of hydrocarbons in this region is based on interpretation of fragments of volcanic rocks called 'pyroclasts' and sediments deposited between the successive lava flows -- called inter-trappean beds — composed of shale, mudstone, black shale, siltstone, sandstone, bentonite (altered volcanic glass) and peperite (alternation of lava and unconsolidated sediment), he added.

“The occurrence of 'oolite' — a kind of sedimentary structure — and thin beds of black shale in the lower profile of the Rajmahal lava stratigraphy give definitive indication of the prospect of hydrocarbons both in the West Bengal basin and the adjoining Rajmahal basin of Jharkhand,” Ghose said.

Ghose first reported his finding in 2010 at the National Seminar on “Geology and Textural Features of the Rajmahal Volcanics in the Eastern Indian Shield Margin” at Calcutta University. “My prediction has proved to be correct from the recent announcement of Essar Oil of its discovery of huge reserves of shale gas in the Raniganj area below the coal-bearing strata,” he said.

He said his observation further indicates the prospect of hydrocarbons in the older sediments of Mesozoic era (252 to 66 million years ago) hitherto considered of lesser significance. “This opens a new domain for exploration of oil and gas in the Gondwana sediments found in abundance in the Indian subcontinent,” Ghose said.