Estimation of S-wave static corrections using CMP cross-correlation of surface waves

Abstract

We utilize the CMP Cross-Correlation of Surface Waves (CCSW) to obtain a high-resolution S-wave velocity model for the calculation of PS receiver static corrections. We cross-correlate each trace of a shot record with a reference trace that is selected from within the shot gather based on high signal to noise ratio. New midpoints that relate to the correlated traces are then calculated. Thereafter, we calculate the phase velocity for each CMP gather, and we convert the resulting dispersion curve to an S-wave model. Moreover, we show that, to achieve a precise estimate of a dispersion curve in a CMP gather, we should only consider those traces whose offsets lay in a spatial window length. We empirically find that an optimum window length (aperture) should be about one to one and a half times of the maximum wavelength of the fundamental mode of surface wave. When the aperture is optimum, we observe a distinguishable trend of the phase velocity of each mode within the dispersion curve that avoids mode misidentification. In addition, we show the importance of wavelength-dependent aperture for estimating the phase velocity when there is a wide range of wavelength in a data set. We obtain static corrections based on an S-wave velocity model obtained from CCSW and successfully apply them to a field data.