Undiscovered Petroleum Resources of South Asia

John Kingston

Sedimentary basins of south Asia (Pakistan, India, Bangladesh, and Burma) evolved from two tectonic events: (1) separation of India from Gondwana, and (2) northward movement of the India block, shouldering past and obliquely subducting under margins of previously arrived blocks (Afghan on the west and Sunda--Burma--on the east) before colliding with the Asian continental mass. The first event resulted in a rifted continental-margin basinal trend along the west coast of India and a similar trend along the east coast. The second event caused three trenches, Indus basin on the west, Bengal-Assam basins on the east, and sub-Himalayan basins to the north. Burma is the fore-arc basin of the eastern oblique subduction.

Taking into account various geologic factors (reservoirs, traps, source, seal, and migration-timing), we estimated six most likely occurrences of undiscovered recoverable petroleum resources. (1) The western rifted margin, the richest trend probably because of its relatively high geothermal gradient, is assessed at 1.3 billion bbl of oil and 13.2 tcf of gas; (2) the eastern rifted margin at 0.82 billion bbl of oil and 10.2 tcf of gas; (3) the western trench (gas-prone) at 0.11 billion bbl of oil and 8.1 tcf of gas; (4) the eastern trench (gas-prone), assessed higher than the western trench because of more favorable reservoir properties, at 0.10 billion bbl of oil and 17.5 tcf of gas; (5) the northern trench, the poorest trend mostly because of the absence of properly matured source ro ks, at 0.10 billion bbl of oil and 0.91 tcf of gas; and (6) the Burma basin, which received a relatively high assessment for a fore-arc basin because of the very thick stratigraphic section, at 0.56 billion bbl of oil and 1.78 tcf of gas.

AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.