Converted Wave Elastic Impedance Inversion

On the basis of reviewing the development of the elastic impedance forward and the inversion problem, much work is done on researching and exploring the inversion problem of P-P wave and P-SV wave with far-offset. By using forward model and real multicomponent seismic data, the accuracy of P-SV reflection coefficient was proved. At the same time, we extended this theory to application and developed the commercialized software package of the P-SV synthetic seismic. I put forward the concept of converted elastic impedance for the converted wave as well. It is the key technique to solve the P-SV wave forward and inversion problem.1. After analyzing the basic principle of the traditional 1 -D acoustic impedance inversion, and discussing the limitation of it, I pointed out the research direction of seismic trace inversion in the future.2. Conventional seismic trace inversion method is based on the assumption of P-wave striking interface normally. However, conventional multi-channel seismic data records are oblique reflections, reflection amplitude is the average value of CDP gathers. Following the idea of Patrick Connolly's (1999) Elastic Impedance (El), the Zoeppritz equation was further approximated and yielded the P-wave reflectivity recursive formula. It is suitable for the post-stack and seismic data of oblique reflection. The so-called Generalized Elastic Impedance (GEI) we proposed solved the key problem of forward modeling and inversion of far offset.3. In multicomponent seismic exploration, the study of forward and inversion problem of converted wave is the key step to interpret P-SV data. We can also regard the convolution model theory as the basic theory for studying the forward and inversion problem. However, the use of convolution model is to deduce recursion formula of the reflection for the converted wave. In this paper, I validated the recursion formula of the P-SV wave reflection coefficient by using Zeoppritz equation and the convolution model. I testified the validity of this recursion formula by calibrating the first ocean bottom cable(OBC) multi-component section in China.4. The recursion formula of the converted reflection coefficient that we put forwarded solved the forwarding problem very well. But it was not satisfied on the inversion of P-SV data for the error of the recursion formula cumulated with the variety of exponent. On the basis of former researchers, I suggested the concept of the converted-wave elastic impedance (CEI) first time. This concept can be used for well calibration, wavelet estimation and inversion of P-SV data. Consequently, it made us easily to understand and interpret converted wave data. Combined CEI with elastic impedance, we can get more accurate physical properties of rock or reservoir than before, such as porosity, permeability, saturation, formation pressure.etc.