BUILDING A HETEROGENEOUS Q MODEL: AN APPROACH USING SURFACE REFLECTION DATA

摘要

The anelasticity of a subsurface medium will cause dissipation of seismic energy. It is challenging to derive an interval Q model in the absence of VSP data and cross-well data. In this paper, we propose a method to derive the Q model using surface reflection data by introducing an effective Q model. Considering the existence of various types of noise, we estimate and evaluate the Q value in terms of compensation effects along with imaging resolution and noise level. Finally, we obtain an optimal compensation result with better resolution and wider bandwidth. Specifically, the effective Q model can be estimated using scanning technology at selected CDP locations to avoid the difficulties of determining a reference event and the thin-bed tuning effect in the conventional spectrum ratio method. The whole Q model can be obtained by a type of interpolation algorithm constrained by geological interfaces, which can be used in the de-absorption prestack time migration directly or in the de-absorption prestack depth migration with the proper time-to-depth conversion. Finally we demonstrate the effectiveness of the proposed approach using a field data example from eastern China. A high-resolution image is obtained.