Abstract

Presence of gas hydrate established in the Mahanadi Basin after coring and drilling under National Gas Hydrate Programs (NGHP) of India. Gas hydrate saturation estimated from the basin to know the reservoir potential and its characteristics. Three sites have been drilled during NGHP Expedition-01 in the Mahanadi Basin used to estimate gas hydrate saturation. Logging-while-drilling (LWD) down hole log data recorded at two sites and at one site wireline log data acquired. Rock physics modeling applied to log data for the estimation of gas hydrate saturation. Gas hydrate saturation estimated from sonic log data by rock physics modeling assumes gas hydrate in the pore spaces of sediments. However, when gas hydrate is formed in marine sediments, the bulk physical properties of host sediments get change due to anisotropy and hence alter the estimated gas hydrate saturation. The estimated gas hydrate saturation at an example site NGHP-01-08 assuming anisotropic media reduces by a factor of two compared to the saturation estimation by assuming isotropic media. Gas hydrate saturation estimated from isotropic P-wave model varies up to more than 16%. The saturation estimated from anisotropic pwave model shows variation up to 8-10% of the pore spaces.