Impact of Diffraction on Resolution of PSDM

Seismic "reflection" data contain at least two types of coherent events generated from the subsurface discontinuities: specular reflections and diffractions. Classical seismic data processing is tuned to imaging and enhancing reflected waves, which carry most of the information about the actual subsurface structure. However, diffractions are generated by local discontinuities which act like point sources. Therefore, the presence of diffractions can indicate faults or fractures, which are important in, e.g., carbonate environments, where locating fractures and their orientation is of major importance for reservoir production. In this paper we investigate the impact of diffractions on prestack depth migration images and discuss some correlated resolution aspects. Ray tracing in its standard forms is not able to produce synthetic seismograms including diffractions. However, we present examples where we apply ray-based approaches to compute synthetic seismograms for both reflected and diffracted events, and to evaluate resolution of PSDM.