Multi-Channel Analysis Of Surface Waves: An Application To Montana Field Data

Abstract

The multi-component (3C or 4C) seismic method is being used to more fully capture the seismic wavefield and to generate complementary P-wave and S-wave (PS) images of the subsurface. One of the complicating issues in processing PS data is the effect of receiver statics. The S-wave receiver static can be quite large due to low S-wave near-surface velocities. We are thus interested in techniques to estimate the shallow S-wave velocity (Vs) structure. The analysis of surface waves (especially Rayleigh waves) has been useful to delineate Vs in near-surface. Multi-Channel Analysis of Surface Waves (MASW) uses the dispersion properties of Rayleigh waves to create a dispersion curve (Park et al., 1998), then S-wave near-surface velocity profile (Xia et al., et al., 1999). We have applied the MASW method to seismic datasets from Elk Basin Oilfield in Bighorn Basin, Montana/Wyoming acquired by students of University of Houston. Vertical and horizontal component seismic lines are analyzed. Preliminary results show extracted S-wave velocities for vertical and horizontal component lines varying between 400-1000 m/sec.