Hydrocarbon potential of east coast of India

The east coast of India is considered to be a divergent margin formed during the fragmentation of Gondwanaland during the late Mesozoic. The four sedimentary basins located along this coast-cauvery, Palar, Krishna-Godavari, and Mahanadi (from south to north)- have their seaward extensions into the Bay of Bengal where some of them have built a 5-6 km (16,000-20,000 ft) thick late Mesozoic to Holocene sedimentary section. The basins have two or more cycles of deposition. During the first (rift) cycle in the Early Cretaceous (stage 1), nonmarine to paralic sandstones and shales were deposited in the interior grabens. The second cycle (coastal margin), during the Tertiary, which is well developed in all basins except Palar, was superimposed unconformably on the horst-graben morphology of the Cretaceous basins. Although no commercial discoveries have been identified to date, significant oil and/or gas shows have been encountered in some of the tests, with definite but lesser shows in others. All important shows observed to date are located on horsts and other structural highs, but stratigraphic controls are very likely to be associated with sub-Upper cretaceous unconformities, between Cretaceous and Paleocene and between Miocene and Pliocene. Oil and gas plays in each sequence appear to bemore » limited by the fault block in which the particular sequence is most completely developed and each appears to contain indigenous source rock providing hydrocarbons to the reservoirs in the sequence.« less