Seismic Constrained Gravity Inversion for Subbasalt Exploration in West Coast, India

Exploration in sub-basalt reservoirs is challenging because conventional seismic fails to image the structures below basalt. Advanced seismic acquisition using long offsets and low-frequency sources as well as improved processing are the possible way-outs. Use of non-seismic data, e.g., Gravity, Magnetic and Magneto-Telluric (MT), along with seismic is being considered as an option to improve subsurface image below basalt. The present work is an integrated approach for better imaging of the sub-basalt structures. We performed a model study over the geological setup of a west-coast basin of India. Above basalt velocity model derived from seismic method is converted into density model and is used as constraint in gravity inversion to delineate the below-basalt density structures. The use of additional constraints from MT is found useful to reduce the uncertainty in gravity inversion. The technique is then used to invert satellite gravity data along the same profile to obtain the base basalt and sub-basalt density structure.