Downward and upward continuation of 2-D seismic data to eliminate ocean bottom topography's effect

摘要

abstract_textpIn order to eliminate the effect of ocean bottom topography on seismic wave field, we transformed curved (x, z) coordinate system grids into rectangular (xi, eta) coordinate system grids and derived a 2-D scalar acoustic wave equation in the xi, eta domain. The seismic wave field collected at the sea surface was downward continued to the ocean bottom by the inverse finite difference method with the water velocity and then was reversely continued to the ocean surface by the finite difference method using the layer velocity from just below the ocean bottom in the (xi, eta) domain. Simulation calculations and practical application show that this method can not only remove the reflection travel time distortion but also correct the dynamic parameter changes caused by the ocean bottom topography. The inverted velocity after wave field continuation is much more accurate than before continuation and the image section was greatly improved compared to the original wave field./p/abstract_text