Patent EA-004003-B1 (EA)
Title: Method and device for converted-wave analysis
Inventor: ZHU XIANHUAI
IPC: G01V1/36
Filed: 2000-04-12
Abstract: 1. A method for processing converted wave seismic data comprising: providing a converted-wave zero-offset gather substantially uncorrected by normal move-out; performing migration on the zero-offset gather; performing velocity analysis on the migrated zero-offset gather; and performing normal moveout correction on the migrated data using the velocity from the velocity analysis. 2. A method as in claim 1 wherein said providing comprises: performing normal move out on the converted wave data using a normal move out velocity, whereby moved out data results; performing dip move out on the moved out data, whereby dip moved out data results; and performing an inverse normal move out on the dip moved out data, using the move out velocity, whereby a zero offset gather is provided as the output. 3. A method as in claim 1, wherein said providing a converted-wave zero-offset gather comprises providing a common conversion point binned gather. 4. A method as in claim 1, wherein said performing velocity analysis comprises performing velocity analysis substantially independent of p-wave velocity. 5. A method as in claim 1, wherein said performing normal moveout correction comprises second order normal moveout correction. 6. A method as in claim 5, wherein said performing normal moveout correction comprises normal moveout correction having orders higher than second order normal moveout correction. 7. A system for processing converted wave seismic data comprising: means for providing a zero-offset gather substantially uncorrected by normal move-out; means for performing migration on the zero-offset gather; means for performing velocity analysis on the migrated zero-offset gather; and means for performing normal moveout correction on the migrated data using the velocity from the velocity analysis. 8. A method as in claim 3 wherein said means for providing a zero-offset gather comprises: means for performing normal move out on the converted wave data using a normal move out velocity, whereby moved out data results; means for performing dip move out on the moved out data, whereby dip moved out data results; and means for performing an inverse normal move out on the dip moved out data, using the move out velocity, whereby a zero offset gather is provided as the output. 9. A method as in claim 1, wherein said providing a converted-wave zero-offset gather comprises providing a common conversion point binned gather. 10. A method as in claim 1, wherein said performing velocity analysis comprises performing velocity analysis substantially independent of p-wave velocity. 11. A method as in claim1, wherein said performing normal moveout correction comprises second order normal moveout correction. 12. A method as in claim 5, wherein said performing normal moveout correction comprises normal moveout correction having orders higher than second order normal moveout correction. 13. A system for processing converted wave seismic data comprising: a migration module positioned and arranged to receive a zero-offset gather and output a migrated set of data substantially independent of velocity analysis; a velocity analysis module positioned and arranged to receive migrated data from said migration module and perform velocity analysis on the migrated data; and a normal moveout correction module positioned and arranged to receive a velocity model from said velocity module and the migrated data from said migration module and perform normal moveout correction on the migrated data using the velocity from the velocity analysis.