Summary
We develop an efficient method to calculate the broadband seismic illumination and resolution. The point spreading function of seismic image contains the full information for illumination and resolution analyses. Physically, it is the image of a point scatter. Therefore we can obtain the illumination information by calculating the point spreading function. We develop a method to better calculate the point spreading function. The scattered waves from background structure are eliminated, Noise from higher-order interscatter multiples are investigated and properly avoided. By converting the point spreading function to the wavenumber domain, methods for illumination and resolution analyses in angle domain are also discussed.
Introduction
Migration image is one of the most important processing techniques that map the reflection data to the target to generate the subsurface image. Due to limited acquisition aperture, complex overburden structure and target dipping angle, the migration often generates a distorted subsurface image. Seismic illumination and resolution analyses provide a quantitative description on how the above mentioned factors will cause the image distortion. These analyses are vital in obtaining true reflection image, AVA analysis, reservoir characterization as well as seismic survey design and processing quality control. Traditionally, seismic illumination and resolution analyses are performed by ray or one-way propagator based methods (Gelius et al., 2002; Lecomte, 2008; Xie et al., 2005, 2006; Wu et al., 2006). To simulate the acquisition system, the wavefield needs be extrapolated from all sources and receivers to the subsurface. Angle decomposition needs be conducted locally in the model space to construct the angle domain illumination. The related computation is extremely intensive. To be practical, the illumination analysis is often conducted under a single (usually the dominant) frequency and with limited number of sources and receivers. Recently, the full wave equation based RTM has become the industry standard. To be consistent with this trend, the broadband, full-wave based illumination analysis method should also be developed.
