Abstract

South Rewa basin of Central India is a complex rift-sedimentary basin having thick column of Gondwana sediments hidden below the Deccan Traps. To image the sub-trappean Gondwana sediments having hydrocarbon potential and delineate the complex subsurface geological structures with basement configuration, longoffset common-depth-point (CDP) seismic reflection data acquired along the N-S trending 127 km long Kuvari-Shahdol profile is used. The conventional stack and pre-stack time migration (PSTM) techniques fail to image the complex subsurface structures dominated by steeply dipping faults. The steeply dipping faults with small-scale structures are influenced by strong lateral and vertical velocity variations that cause problems in imaging the basin. Hence, a robust tomographic inversion for the velocity model building with pre-stack depth migration (PSDM) technique is adopted to image fine-scale subtle subsurface geological structures with smooth velocity variations. The tomographic velocity model and PSDM seismic image could decipher basaltic trap thickness, numerous dyke intrusions, alternate horsts and grabens with deposition of thick hydrocarbon-bearing sub-trappean Gondwana rocks along with the basement configuration. The deep basinal faults with highly distorted basement structures represent the intense tectonic activity of this Gondwana riftbasin. The deep-seated hydrocarbon reservoir is discovered with an excellent trapping mechanism forming both pre-rift and syn-rift settings of the rift-basin. The large basement faults, horsts and grabens, several intrusive like dyke, sill, laccolith, and thick sub-trappean Gondwana formations with Deccan Trap cover indicate complex geology and tectonic settings with suitable provenance of hydrocarbon potential in this sedimentary basin of India.