Summary
We apply interferometric theory to solve a 3D seismic residual statics problem that helps to improve reflection imaging. The approach can calculate the statics solutions without picking the first arrivals in shot or receiver gathers. The statics accuracy can be improved significantly since we utilize stacked virtual refraction gathers for calculation. Because sources and receivers can be placed at any position in a 3D seismic survey, the arrival times of virtual refractions for a pair of receivers or sources are no longer the same as in a 2D case. To overcome this problem, we apply 3D Super-Virtual Interferometry (SVI) method in the residual statics calculation. The virtual refraction for the stationary source-receiver pair is obtained by an integral along source or receiver line without the requirement of knowing the stationary locations. Picking the maxenergy times on the SVI stacks followed by applying a set of equations is able to derive reliable residual statics solutions. We demonstrate the approach by applying to synthetic data as well as real data.
Introduction
Rugged topography and complex near surface layers are some of the important challenges that we are facing in seismic data processing today. Residual statics due to near-surface velocity variations may not be able to be resolved through the near-surface model imaging, but critical for seismic data processing.
There are many methods to calculate residual statics solutions, such as reflection stack-power maximization method (Ronen and Claerbout, 1985), refraction waveform residual statics (Hatherly et al., 1994), and refraction traveltime residual statics (Zhu and Luo, 2004). For refraction methods, the accuracy of the refraction static correction largely depends on the quality of the first arrival traveltimes. However, seismic amplitudes at far offsets are often too weak to pick. To overcome this problem, the theory of Super-Virtual Interferometry (SVI) is developed to generate headwave arrivals with improved SNR (Bharadwaj and Schuster, 2010). The SVI method is later used to calculate 2D residual statics solutions without picking first arrivals (Zhang et al., 2014). In this study, we follow Lu et al. (2014) to extend SVI to 3D and apply that to solve a 3D residual statics problem.
