A Methodology to Estimate Residual Source Statics from 2D/3D VSP Data

Abstract

Summary The estimation and correction of residual source statics is critical to the accurate imaging of land WVSP (walkway VSP) and 3D VSP data. We present here a new methodology to estimate residual source statics from WVSP and/or 3D VSP data. We adapt the Fomel and Stovas’ traveltime function originally developed for surface seismic reflection moveout corrections to fit the first-break (FB) times in WVSP or 3D VSP data with large source offsets, for any anisotropic (VTI) layered velocity model. We employ a global optimization algorithm called simulated annealing (SA) to automatically search for the four parameters in the Fomel and Stovas’ traveltime function. After the best-fit FB time function is solved, the residual source statics are straightforwardly derived by calculating the deviation of the FB time of each source from the fitting function curve. We demonstrate the accuracy and robustness of our methodology using synthetic model data and a field WVSP dataset. The end result of the application of accurate residual statics is better migration focusing and subsequent improvement in the image quality of the VSP data.