Time‐shift Angle Domain Common Image Gathers for Multiwave

Abstract

On the vector wavefields imaging problem, the elastic imaging condition can be extended to non-zero time and space shifts. Through the introduction of space-time-shift imaging condition to elastic Kirchhoff migration, the P-waves and PS converted waves time-shift offset domain common image gathers (TSODCIGs) and time-shift angle domain common image gathers (TSADCIGs) can be quickly extracted. These new gathers contain more useful seismic wavefields information than the angle gathers produced by space-shift or timeshift imaging condition. Based on the multiwave TSODCIGs and TSADCIGs, the accuracy of migration velocity analysis (MVA) for multiwave will be improved. Furthermore, this paper operates directly on vector wavefields which removes a requirement for wavefields separation in the preprocessing, and the method can realize joint MVA for multiwave. The superiority of the time-shift angle domain common image gathers is shown by comparing the results of TSODCIGs and TSADCIGs.