Potential natural gas hydrates resources in Indian Offshore areas

Abstract

Large amount of multi-channel seismic reflection data was acquired by oil industry for exploration of hydrocarbon in the Indian Deepwater basins, beyond 400m isobath. These data were examined for BSRs, blanking above BSRs, polarity reversals etc (geophysical proxies of gas hydrates). A qualitative map prepared based on the inferred BSRs brought out a deepwater area of about 80,000 sq.km unto 3000 m isobath as favourable for gas hydrate occurrence. Methodology for reprocessing of seismic data was evolved during 1997 to infer BSRs (gas hydrates) by ONGC in collaboration with University of Victoria (UV), Canada. Subsequently several seismic line segments from the Indian offshore areas were reprocessed. Clear BSRs cutting across the sedimentary strata supported with interval velocity inversion in Krishna-Godavari deep offshore Basin were observed. The swath bathymetry maps generated for Eastern and Western offshore areas depict the seafloor morphology. Based on the encouraging results of these initial studies, further reprocessing of the seismic data was carried out by ONGC in a selected area in the Krishna-Godavari Basin