State-run Oil and Natural Gas Corporation (ONGC) will start drilling in the ultra deep waters of the Cauvery basin in the next financial year beginning April 2023.

These are part of the domestic exploration and production (E&P) major’s efforts to scout for hydrocarbons in ultra deep waters along India’s eastern and western coast.

“We also have a lot of foreign MNCs who are interested and they are studying data. They are looking into various financial and administrative regulatory policies and seeing whether it is conducive,” ONGC Director (Exploration) Sushma Rawat told businessline.

Situated along India’s east coast, the Cauvery basin is spread over 1.5 lakh sq km, which comprises on-land (25,000 sq km), shallow offshore areas (30,000 sq km) and deep water offshore areas (around 95,000 sq km).

For exploration and extraction of oil & gas from complex and ultra deep waters along the east and west coasts, ONGC has inked memorandum of understandings (MoUs) with oil giants ExxonMobil and Chevron.

“The MoUs are for conducting joint and individual technical studies. We expect Exxon’s study to end by March and Chevron’s by December 2023. They will move ahead once these studies are over,” Rawat added.

Exploring ultra deep waters

Rawat explained that the government has freed a lot of ‘no go’ zones, particularly in the western and eastern off-shore.

“ONGC has been trying to acquire more acreages off-shore. We have a good idea of oil & gas availability in the eastern and western off-shore. Our target is to acquire almost 1 lakh sq km of acreage every year so that we can have an acreage of 5 lakh sq km in the next three years,” she added.

The PSU conducted basin scale models of petroleum system modelling (PSM) and has also come up with common risk segment maps, which detail the hydrocarbon potential in terms of generation and accumulation.

There are many acreages, even within category-1 basins, that need to be probed through drilling, which is why ONGC is exploring partnerships for deep and ultra deep waters, Rawat emphasised adding, the company can go to water depths of more than 2,500 meters.

Category-1 basins are those which have reserves and have started production.

“We are also seeking partnerships in terms of data processing. With ExxonMobil, we have inked an MoU and they have purchased seismic data from the National Data Repository of the Directorate General of Hydrocarbons. Similar is the case with Chevron,” she said.

Exploration activity

Since FY20, ONGC as a part of its exploration activity has acquired 4,118 line km (LKM) of two-dimensional (2D) data and 18,519 sq km of three-dimensional (3D) seismic data.

It has drilled 323 exploratory wells, which established around 132.65 million tonnes (MT) of 2P (Proven and Probable) Oil Initially In-Place (OIIP) reserves with 43.5 MT estimated ultimate recovery (EUR).

The E&P major has oil reserves in eight sedimentary basins, which have a total 2P reserves of 326.87 MT as of April 2022. 

Since FY20, under the National Seismic Programme (NSP), the government acquired 2D seismic data of 46,960 LKM.

Besides, another 22,500 LKM of 2D seismic data was acquired in the Andaman offshore and 32,435 LKM of data under the Exclusive Economic Zone (EEZ) survey till January 15, 2023.