Converted-wave (P-SV) data processing and interpretation for 3-D surveys: a physical modeling example

Donald C. Lawton, Shaowu Wang

Including converted-wave (P-SV) data in seismic programs can provide for a more fully integrated interpretation than that obtainable from P-P data alone. Physical modeling has proved to be a very useful way to evaluate experimental design, data processing algorithms and interpretation methods for 3-D converted-wave survey. With the aid of a 3-D converted-wave data set over a 3-D physical model, an isotropic 3-D processing flow for converted-waves was developed. Due to the asymmetry of the P-SV raypath, data processing differs from that for P-P waves and involves special processes, such as component rotation, P-SV NMO correction and common conversion point (CCP) binning.

Comparison of P-P and P-SV migrated sections from a sample physical model showed very good correspondence. However, although the model is symmetric in the receiver-line direction, P-SV events were found to be asymmetric over the flanks of the model, probably because of the asymmetry of P-SV raypaths and the particular design of the survey. The application of single-pass phase-shift migration proved to be successful for migrating the converted-wave data, given a good stacked section and an accurate velocity estimation.