Application of paleo-structural and seismic sequence stratigraphy analysis to determine the potential plays within the Proterozoic sequence of the Ganga Basin, India

Abstract

Gas discovery in Nohta-2 well from Proterozoic Rohtas plays in Vindhyan Basin, south of Ganga Basin has been a significant lead to suggest that Proterozoic sediments underneath Ganga Basin could be prospective. With this in view, the Govt. of India (GOI) acquired 1350 LKM (Line kilometer) of 2D regional seismic lines to image the Proterozoic sediments for the first time within the basin under National Seismic Program (NSP). The present study is carried out to understand the paleo structures, the nature of the sedimentary sequences, and the trapping mechanism to further visualize the prospectivity of the Proterozoic sequence within the basin. The paleo-tectonic and seismic sequence stratigraphy analysis reveals that the Proterozoic sediments were deposited in the passive margin setting in shallow marine and tidal conditions with several progradations and retrogradation cycles. Precisely, it is noticed that the Proterozoic sediments experienced two stages of progradations and retrogradations. That was followed by a long non-depositional hiatus (>500 Ma) spanning from the Paleozoic to Mesozoic ages which led to a regional unconformity throughout the basin as well as other local unconformities and hydrocarbon traps within the Proterozoic sediments. Four giant structural traps (>300 km2) and one combination trap (>500 km2) are identified within Neo-Proterozoic to Meso-Proterozoic sequence and are expected to be prospective. However, with more exploration efforts and additional data, these traps may lead to a paradigm shift in exploration strategy and discoveries in near future within the basin.