Estimating Elastic Constants From A Raw Seismic Reflection Data By Performing Turning Ray Tomography

Abstract

A common technique in seismic inversion for estimating near surface velocity model is Turning Ray Tomography (TRT) which would employ the available 2D seismic reflection data in conjunctions with set of mathematical equations to calculate the elastic constants and interpret the lithology of the subsurface of the earth. In addition, knowing the elastic constants is not only an important issue in civil engineering, but also in mining engineering. Thus, it is necessary to describe the mathematics of the medium?s elasticity, taking into consideration homogeneous and isotropic media. In this technique, the velocity model was computed from a 2D seismic reflection data. This resulted in the reconstruction of the velocity model accurately as the seismic waves travel. TRT result showed only a P-wave velocity model. However, this is insufficient to calculate the elastic constants and predict the lithology, which also require an S-wave velocity and a density. The S-wave velocity was calculated by using Castagna?s equation, while the density was computed by applying Gardner?s equation. Furthermore, the remaining elastic constants were calculated by using their relationships with P-wave velocity, S-wave velocity and the density. Consequently, the results showed that the near-surface velocity model derived from TRT was capable of computing the elastic constants.