ONGC and OIL target Andaman Basin as key frontier in India’s energy exploration

Two Mahartana Oil PSUs, ONGC and Oil India Ltd have launched an ambitious exploration campaign in the Andaman ultra-deepwater region. Drilling operations will target the depths of up to 5000 metres. One such wildcat well, ANDW-7, drilled in a carbonate play in the East Andaman Back Arc region, has yielded encouraging geological insights.

These include traces of light crude and condensate in cutting samples, heavy hydrocarbons like C-5 neo-pentane in trip gases, and the presence of reservoir-quality facies.

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These findings establish, for the first time, the existence of an active thermogenic petroleum system in the region, comparable to those in Myanmar and North Sumatra. While commercial reserves remain to be established, this campaign has validated the presence of a working petroleum system and laid the foundation for focused exploration in the area.

While providing an overview of the exploration outcomes till now, the Petroleum Minister informed that ONGC has made hydrocarbon discoveries in 20 blocks, with an estimated reserve of 75 million metric tonnes of oil equivalent (MMTOE).

Further, OIL has made seven oil and gas discoveries over the past four years, with reserves estimated at 9.8 million barrels of oil and 2,706.3 million standard cubic meters of gas.

Referring to the Hydrocarbon Resource Assessment Study (HRAS) of 2017, which estimated the AN basin’s hydrocarbon potential at 371 MMTOE, the Minister stated that a 2D broadband seismic survey covering approximately 80,000 Line Kilometres (LKM) of India’s Exclusive Economic Zone, including the AN offshore region, was completed in 2024.

Additionally, OIL acquired 22,555 LKM of 2D seismic data during the Deep Andaman Offshore Survey conducted in 2021–22. Several promising geological features have emerged from this data, which are now being validated through ongoing drilling campaigns by ONGC and OIL.