Pre-stack Joint Inversion For Elastic Parameters

Seismic P-wave velocity,S-wave velocity,the density of the rocks,P-wave modulus,S-wave modulus,Young's modulus and Poisson's ratio are important elastic parameters to describe the properties of the reservoir rock,evaluation of oil and gas reservoir characteristics.With the increasing difficulty of exploration,how to distinguish accurate effective reservoir characteristics of elastic parameter accuracy from seismic data becomes the research hot spot.Pre-stack inversion includes full waveform inversion which based on wave equation,and AVO/AVA inversion which based on Zoepppritz equation and its approximate expression.AVO/AVA inversion can not only use pre-stack seismic data,but also multi-scale data,such as test data.At these stages AVO/AVA inversion becomes people's popular pre-stack inversion method.Because of the complexity of the Zoepppritz equation itself,AVO/AVA inversion method using approximate expression of Zoepppritz equation for the formula derivation,then realize the direct inversion of elastic parameters.But the limitations of approximate expression itself leads to pre-stack seismic data cannot be effectively used,and in the follow-up study will also introduce many approximate limit.To solve these problems,we start with the Zoepppritz equation,and based on the elastic theory to deduce respectively P-wave modulus,S-wave modulus and density of reflection coefficient equation,and the Young's modulus,Poisson's ratio and density of reflection coefficient equation,the equation of the derivation process of did not do any approximation with parameters,so the precision is indisputable.And based on the generalized linear inversion method not only established the traditional P-wave velocity,shear S-wave velocity and density inversion method,can also build P-wave modulus,S-wave modulus and density,Young's modulus and Poisson's ratio coefficient and density inversion method,those methods effectively avoid the limitation of using approximation as well as the elastic parameters inversion method.Model test and real data test show that those methods can get elastic parameter based on pre-stack seismic data,and thus provide reliable directly inversion method for elastic parameters to identify the lithology and fluid analysis and reservoir prediction.