Improvement of seismic velocity model by selective removal of irrelevant velocity variations

In the presented study, a new strategy for smoothing seismic velocity model is introduced. The presented strategy employs various approaches in suppressing velocity errors and removing geologically irrelevant velocity variations. Here, the background seismic velocity model is separated using the trend surface or the upward continuation methods. Result of subtracting the background velocity from the original velocity model is preserved as the residual velocity model. High frequency variation in residual velocity model, mirrors detail subsurface geological variations. However, velocity errors that appears through velocity model building are also laid in the high frequency component of the velocity model. Filtration of the residual velocity model is generally known as an appropriate approach to remove velocity errors and unwanted velocity variations. However, the high frequency component of velocity model that are related to geological details have to be differentiated from velocity error in advance. The removed content from the residual velocity model then would be analyzed to evaluate efficiency of the filtering procedure. Here we proposed using geological evidences for optimization of the filtering parameters. Subsequently, the separated background velocity and the filtered residual velocity models would be integrated to build the final velocity model. This final velocity model used in prestack depth migration procedure to investigate influence of velocity filtering or velocity smoothing with the proposed method on the final seismic image. The proposed strategy was applied on a seismic data from complex media with two different initial velocity models obtained through normal move out velocity analysis and normal incidence point tomography inversion. Appropriate parameters were obtained for both methods. Evaluation of results and investigation on the final seismic image used filtered velocity model with the proposed strategy depicted capabilities of the introduced method. It was depicted that the methodology is capable in obtaining appropriate seismic image with plausible velocity model. Graphical abstract