Diffraction stacking with stacking velocity analysis in a surface seismic survey--Its application to marine reflection seismic data--

摘要

In our previous paper, we proposed a prestack time migration (PSTM) method whose data processing scheme is analogous to that of conventional CMP method. In the present paper, proposed data processing procedure is applied to marine seismic data collected in the Eastern Nankai Trough. The purpose of this paper is to reveal the feasibility of our method in case of application to real field data. We compare a cross section by PSTM with a cross section by conventional method (CMP stacking Post stack migration) and study the S/N ratio of both sections based on quantitative evaluation by use of f-x prediction filtering which separates coherent components from random components. We also consider the effect of stacking aperture (defined as an angle range of collecting seismic traces) on the S/N ratio and spatial resolution of obtained cross section. In order to reduce computation time and memory requirements, we have developed a PSTM code for distributed memory parallel machine systems. The input data size is about 1 Gbytes and the output image after PSTM has totally 1.85 million samples. The process of PSTM can be completed in a practical time (100 minutes) using 256 processors.