3D Seismic-gravity Simultaneous Joint Inversion for Near Surface Velocity Estimation

A novel 3D simultaneous joint inversion scheme for gravity and seismic travel time data is developed to solve for near-surface complex velocity distributions. The method incorporates industry-standard gravity and travel time inversion techniques while the joint inversion problem is solved by the introduction of various regularization functions about the model such as a-priori parameter distribution information, solution-space bounds, structural similarity via cross-gradient constraints and rock physics relations. The effectiveness of our joint inversion is demonstrated against a synthetic model representing a complex pattern of near-surface anomalies incorporating low and high velocity and density bodies. Results demonstrate the superiority of our approach where the shallow anomalies are better reconstructed by the joint inversion rather than that obtained by the single-domain inversions. The developed algorithm is tested with real data from Saudi Arabia acquired over a wadi structure. The results show a significant uplift of the time stack using the seismic-gravity joint inversion velocity model. The developed methodology is part of a multi-geophysics platform for near-surface velocity model building in complex geology scenarios.