A robust Q estimation scheme based on an improved centroid-frequency shift method for strongly attenuating media

This paper proposes an improved frequency shift method to estimate the inverse quality factor 1/Q for strongly attenuating media. The near-surface zone is often quite loose and characterized by very low Q factors. Such damping makes the seismic wavefield complicated. The commonly used attenuation estimation methods, such as the central frequency shift (CFS) method, and the central frequency shift method based on a frequency-weighted exponential function (FEW-CFS), have their respective limitations for signal processing in low Q regions. Here, we derive a novel Q-estimation approach without constant parameter fit processing, and adapted for symmetric or asymmetric wavelets. It yields more stable and accurate results. This proposed approach has been successfully applied on synthetic data and actual VSP survey data. When compared with traditional CFS and FEW-CFS methods, the new method offers improvements in robustness, flexibility and accuracy.