Seismic characterization of hydrates in faulted, fine-grained sediments of Krishna-Godavari basin: Unified imaging

[1] A combination of diffusion and advection in fine grained sediments can create a patchy Bottom Simulating Reflector (BSR) which has little to no apparent correlation with the overlying hydrate distribution. Using 2D seismic data from faulted, clay-rich sediments in the Krishna-Godavari (KG) basin, we show both the hydrate distribution and the BSR structure are fault controlled. Our demonstration hinges upon a kinematically accurate P wave velocity (VP) model which is estimated using a composite traveltime-inversion, depth-migration method in an iterative manner. The flexibility of the method allows simultaneous usage of traveltimes from multiple, discontinuous reflectors. The application begins with a simple VP model from time processing which is reflective of a diffusive, continuous, hydrate– and free gas–bearing system. The application converges in three iterations yielding a final VPmodel which is suggestive of a patchy distribution of hydrates and free gas possibly developing through a combined diffusive-advective system. The depth image corresponding to the final VP model can be interpreted for faults that suggest ongoing tectonism. The BSR appears to be truncated at active faults zones. Both the final VP model and the corresponding depth image can be reconciled with the hydrate distribution and BSR depth at logging/coring sites located ∼250 m away from the line by projecting the sites along the strike direction of the regional faults.