Image - space wave - equation tomography for quality factor Q

Quantitative estimates of quality factor Q are useful for a variety of applications, ranging from seismic-acquisition design, to seismic processing, amplitude analysis, and reservoir characterization. However, Q model building, which is conventionally done in the data space using ray-based tomography, is a notoriously challenging problem due to issues like spectral interference, low signal-to-noise ratio, diffractions, and complex subsurface structure. I propose to produce reliable Q models using a new approach with two major features. First, this method will be performed in the image-space, which uses downward-continuation compensation migration with Q to stack out noise, focus and simplify events, and provide a direct link between the model perturbation and the image perturbation. Second, this method uses wave-equation Q tomography (WEQTom) to handle the complex wave propagation. The implementation of the compensation migration and WEQTom operator builds the cornerstone of the proposed process, and the preliminary results on a simple 2-D example demonstrate its feasibility. Finally, a synthetic test on a 2-D model with multiple reflectors and a Gaussian Q anomaly shows the capability of this method on a realistic structure with a gas cloud.