POSTSTACK VELOCITY ANALYSIS BY SEPARATION AND IMAGING OF SEISMIC DIFFRACTIONS

Abstract

Small geologic features manifest themselves in seismic data in the form of diffracted waves, which are fundamentally different from seismic reflections. Using two field-data ex-amples and one synthetic example, we demonstrate the possi-bility of separating seismic diffractions in the data and imag-ing them with optimally chosen migration velocities. Our cri-teria for separating reflection and diffraction events are the smoothness and continuity of local event slopes that corre-spond to reflection events. For optimal focusing, we develop the local varimax measure. The objectives of this work are velocity analysis implemented in the poststack domain and high-resolution imaging of small-scale heterogeneities. Our examples demonstrate the effectiveness of the proposed method for high-resolution imaging of such geologic fea-tures as faults, channels, and salt boundaries.