Oil and gas bearing basin of the bay of Bengal: A potential hydrocarbon reserve if South Asia

The basin of the Bay of Bengal is situated in the northeastern part of the Indian Ocean. Its floor is covered with the deposits of the deepest underwater fan of the World Ocean. Three sedimentary basins-Bengal proper, Krishna-Godawari, and Koromandel-are distinguished around the Bay of Bengal; all of them extend to the aquatic area of the bay. Estimations of oil and gas generation under the floor of the Bay of Bengal suggest that this process is most intensive in the northern part of the bay, where the thickness of the sediments exceeds 11 km. There, the maximum densities of oil and gas generation reach approximately 2-7 x 10(6) t/kM(2) and 3-11 X 10(6) m(3)/km(2). In the southern half of the basin, these values are 20 times smaller for oil and 110 times smaller for gas. These kinds of foci of oil and gas generation are regarded as large, which is confirmed by the discoveries of giant fields in the last two ears in the Krishna-Godawari basin (with oil reserves of more than 400 Mt and those of gas of 340-425 Gm(3)) and in the Nicobar alluvial fan. The section interval corresponding to the focus of oil and gas generation contains sediments from the Upper Miocene to the Lower Cretaceous. The alteration of reservoirs (sands) and caprocks (clays), together with the enrichment of the latter in organic matter, determined the high potential of the deltaic, avant-deltaic, and turbidite sediments. The reserve of hydrocarbons in the turbidites is estimated at more than 1.2 Gt.