OS3B-5:GAS-HYDRATES IN INDIA, A MAJOR ENERGY RESOURCE FOR THE NEXT GENERATION

Kalachand SAIN^*

Gas-hydrates group, CSIR-National Geophysical Research Institute, INDIA

Gas hydrates have attracted the attention of geo-scientific community due to their abundant occurrences in outer continental margins and permafrost regions, huge potential as a viable major energy resource of future. The bathymetry, seafloor temperature, total organic carbon content, sediment-thickness, rate of sedimentation, geothermal gradient imply that shallow sediments of Indian offshore are good hosts for gas hydrates. The methane within gas hydrates has been prognosticated to be more than 1500 times of India's present natural gas reserve. Even 10% production from this treasure can meet India's overwhelming energy requirement for about one hundred years. Thus, it was felt necessary to map the prospective zones of gas-hydrates and evaluate their energy potential along the Indian margin. The gas hydrates stability thickness map, which provides the maximum depth of gas hydrates stability field, has been prepared along the Indian margin. Analysis and scrutinizing of multichannel seismic data have revealed bottom simulating reflectors or BSRs (marker for gas hydrates, and often coincide with the base of gas hydrates stability field) on seismic sections in the Krishna-Godavari, Mahanadi, Cauvery, Andaman, Kerala-Laccadive, Kerala-Konkan and Saurashtra basins respectively. Seismic attributes like the reflection strength, blanking, attenuation and instantaneous frequency have been computed into these basins to characterize whether the BSRs are related to gas-hydrate reservoirs. Several approaches based on seismic traveltime tomography, full-waveform inversion, amplitude versus offset modeling, impedance inversion, each coupled with rock-physics have been developed for the delineation and assessment of gas hydrates, and their applications will be presented to marine seismic data in various offshore basins of India