India's Petroleum Systems: Past Performance and Future Potential

Rowley, Eleanor J.; Desai, Ashesh; Tandon, Seema
Exploration, Cairn India, Gurgaon, India.

India has a long history of hydrocarbon exploration with the first commercial oil discovery made in the Assam Basin of northeast India in 1889. The subsequent century saw large tracts of the onshore and shallow water basins explored with significant oil discoveries made in the western Cambay and Bombay Basins and the eastern Cauvery and Krishna Godavari Basins. The last decade has seen 2 new frontiers opened up: a deepwater gas province in the Krishna Godavari Basin and a new oil province in the Barmer Basin in northwest India. India's discovered commercial resource base is ~ 26 BBOE, 49% oil and 51% gas, with 96% of these resources found in 6 basins, and 87% trapped in Tertiary plays in India's margin basins. Three of these basins have so far proven to be world class with success ratios of over 40% despite only moderate exploration maturity. With 7,500 km of coastline, India has one of the world's longest coastlines and a key question that remains is how much of the deepwater offshore areas will be prospective. Whilst the relatively early success of the deepwater Krishna Godavari basin resulted in large turbidite-reservoired gas discoveries, subsequent exploration elsewhere on the east coast has resulted in more modest success. Cairn's recent successful well campaign in the Mannar Basin (Sri Lanka) offers an encouraging new frontier that could ultimately deliver significant oil and gas volumes. The deepwater west coast remains lightly explored due to challenges imaging under the thick Deccan basalts, but both oil and gas potential exist sub-basalt. East Africa's recent rash of gas discoveries have some of the same petroleum system elements and may stimulate interest in India's west coast. The Himalayan foreland basin represents another poorly explored frontier, which by analogue with other fold and thrust belts e.g. Canada, could be prospective, however only oil and gas shows have been encountered to date. Whilst India's margin basins are Mesozoic in age reflecting Gondwana break-up timing, India's interior basins are older with Protreozoic and Palaeozoic fills. To date there are no commercial discoveries, but these basins are increasingly being targeted for coal bed methane, and pending a bidround, shale gas exploration. In conclusion, at least 3 of the proven basins in India remain uncreamed and there could be significant conventional and unconventional potential in India's pre-Tertiary plays which are highly under-explored both on and offshore.

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012