Diffraction Imaging for Fracture Detection

The present way in fractures studies usually consists in using indirect indicators such as anisotropy, well log information etc. On the other hand, it is diffracted waves that contain direct and the most valuable information about fracture presents in the subsurface. Diffracted waves are fundamentally different from seismic reflections conventionally used in seismic method. Using synthetic and field data examples, we demonstrate the possibility of separating seismic diffractions in the data and imaging them with optimally chosen migration velocities. Our criterion for separating reflection and diffraction events is the smoothness and continuity of local event slopes. Our criterion for optimal focusing is the local varimax measure. The objective is fast velocity analysis in the pre-stack or post-stack domain and high-resolution imaging of small-scale heterogeneities.