Suppressing VSP migration artifacts and noise by selected‐aperture migration and damped ‐ least ‐square smoothing

Abstract

Vertical seismic profile (VSP) data usually provides a higher resolution seismic image than surface seismic data. This can be attributed to the fact that the geophones are located closer to the reflecting interfaces and therefore can record higher seismic frequencies without attenuation and interference by the free surface. However, due to the limited number of receivers that can be placed downhole relative to a surface survey, and the subsequent narrow acquisition aperture and low CDP fold, VSP migration images from 2D Walkaway VSP (WVSP) or 3D VSP data often contain strong migration artifacts, a visible acquisition footprint, and other coherent or random noise. The presence of these migration artifacts and noise sometimes makes it difficult to reliably interpret VSP image results. This paper discusses two data processing options to attenuate these artifacts and noise. First, through defining and selecting an appropriate migration aperture angle, we can significantly attenuate migration artifacts in migrated VSP images. Second, we introduce a damped‐least‐squares smoothing method to suppress the VSP acquisition footprint and other random noise that can be present in the VSP images. We demonstrate the effectiveness of these processing.