Polarization filter: Design and testing
Ye Zheng, Robert R. Stewart
A polarization filter is designed to process three-component seismic data. The design is based on covariance matrix analysis. Rectilinearly polarized waves are enhanced and non-rectilinearly polarized waves are attenuated. This filter has been successfully applied to field data to reduce random noise and groundroll. After applying the polarization filter, different types of waves (such as P, SV and SH wave) can be distinguished. The direction of an impinging wave may be determined if directional analysis is applied to the polarization-filtered data. However, because spherically polarized noise also affects the trajectory direction of the data, directional filtering after polarization filtering should be used very carefully. Only in some circumstances, can directional filtering get good results. If the signal-to-noise ratio is low on the original data, an erroneous result may occur. This technique may be helpful for shear wave and converted wave exploration.