Abstract

Mahanadi Deepwater Offshore Basin has been the focus of active exploration under the aegis of large number of multinational companies for more than a decade now. Extensive 3D seismic coverage in many exploration blocks in the basin along with several deepwater drilled wells information so far have helped to unravel the subsurface tectonics, structure and stratigraphy of the basin to a great detail. The major deepwater depositional elements in the basin consist of channel-levee complexes, crevasse splays, meandering cut-off bars, slope and basin floor fans, mass transport complexes, shelfal carbonate platform, reefal carbonate growth, prograding carbonate complexes etc out of which some of the Mio - Plio channel levee complexes have already proved to be gas bearing, charged mainly by biogenic gas. Recently, evidence of thermogenic gas has also been established in Paleogene sandstone reservoirs of one of the exploration block indicating the probable presence of thermally rich source rocks either in the Mesozoic rift related sediments or in Early Tertiary deepwater shales.