Reflection Fresnel Volume Tomography

According to the finite-frequency theory, for a single source-receiver pair, not only the points on the ray-path, but also those outside the ray affect wave propagation. This kind of effect can be described by a sensitivity kernel. On the basis of earlier studies of the Fresnel Volume tomography (FVT) of transmitted waves, a new approach, Fresnel Volume tomography of reflected waves (RFVT), is proposed here. In addition, the traveltime sensitivity kernel of RFVT for homogeneous media is analyzed. To overcome the coupling between velocity and depth of layered media, a decoupling strategy is proposed which inverts the velocity and depth alternatively using an iterative approach. This strategy makes use of the zero-offset or near-offset stack section of the seismic records and can be performed on one layer at a time. Finally, using existing calculation methods on the boundaries of a band-limited Fresnel Volume, RFVT is performed on a synthesized data set. The inverse results indicate that RFVT can achieve higher accuracy and better vertical resolution than conventional reflection ray-path tomography (RRT), with both methods using the same decoupling strategy.