System and method for velocity analysis in the presence of critical reflections

A computer system, comprising:

• one or more processors;
• memory;
• and
• one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions that when executed by the one or more processors cause the device to:
• receive a seismic data gather that includes a high-velocity-contrast event arranged as a function of an angular offset parameter, wherein the high-velocity-contrast event includes one or more post-critical traces whose respective angular offset parameters are greater than a critical angle of the high-velocity-contrast event;
• apply a wavelet de-stretch filter to the seismic data gather, wherein the wavelet de-stretch filter corrects wavelet stretching;
• apply a fan-filter to the seismic data gather to remove coherent noise;
• pick residual moveout of events including the high-velocity-contrast event;
• and
• apply a median-filter to the residual moveout to reduce the impact of phase change of the high-velocity-contrast event in the one or more post-critical traces, wherein the median-filtered residual moveout is used for improving a velocity model used for generating the seismic data gather.

A non-transitory computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by an electronic device with one or more processors and memory, cause the device to:

• receive a seismic image gather that includes a high-velocity-contrast event arranged as a function of an angular or offset parameter, wherein the high-velocity-contrast event includes one or more post-critical traces whose respective angle or offset parameters are greater than a critical angle of the high-velocity-contrast event;
• apply a wavelet de-stretch filter to the seismic image gather, wherein the wavelet de-stretch filter corrects wavelet;
• apply a fan-filter to the seismic image gather to remove coherent noise;
• pick residual moveout of events including the high-velocity-contrast event;
• and
• apply a median-filter to the residual moveout to reduce the impact of phase change of the high-velocity-contrast event in the one or more post-critical traces, wherein the median-filtered residual moveout is used for improving a velocity model used for generating the seismic data gather.