Examination regarding High-Angle structure Imaging by seismic interferometry

Abstract

Seismic interferometry is an investigation method used to deduce geological structures in the subsurface, by performing cross-correlations between the traces of each record and synthesizing similar data obtained by reflection seismic surveying on surface. Seismic interferometry can be applied to various observation geometries, because it does not need regular seismic source points. The application of seismic interferometry to borehole geophysical surveys, such as VSP and cross-hole tomography, can be expected to provide clearer images of high-angle faults. In this study, to confirm the applicability of seismic interferometry to VSP data, the model simulation performed assumed a granitic rockmass with a high-angle fault. In this model simulation, the effectiveness of seismic interferometry using deconvolution (Vasconcelos and Snieder, 2008a; Vasconcelos and Snieder, 2008b) was confirmed. The reflection image obtained from seismic interferometry using deconvolution has a high signal to noise (S/N) ratio compared to reflection images from normal seismic interferometry. The reflection image has good correspondence with a high-angle fault in the model. As well, seismic interferometry was applied to Multioffset VSP field data. The results indicated that a reflection image from a high-angle structure could be extracted from the profile.