Prediction Of Geological Dessert In Shale Gas With Pre-stack Seismic Inversion

Seismic fluid identification refers to the use of seismic data to identify and describe reservoir fluid characteristics.Seismic prestack inversion is an effective way to identify and predict the shale gas geological dessert.The shale reservoir,which an unconventional gas reservoir,based on the seismic data to achieve reservoir geological dessert prediction,which is one of the widely studied and important issues.In this paper,we will regard the geological dessert inversion method as a target,which based on the prestack seismic inversion theoretical method,analyzing the physical parameters and elastic parameters which affect the gas sensitivity of the shale gas reservoir.Studying a method for predicting the geological dessert of shale gas reservoirs which using the elastic impedance to inverse these parameters.This paper presents a method to predict geological dessert for prestack seismic inversion of shale gas reservoirs,including shale gas flow factor prestack seismic inversion method and shale gas reservoir TOC prestack seismic inversion method.The first method,The shale gas indicator factor is constructed by Russell approximation formula is a relatively accurate,and the objective function is deduced under the framework of Bayesian theory.Finally,we can obtain the shale gas indicator factor with the elastic impedance inversion.Then,we propose a predicted method of fluid phase in shale gas reservoir with pre-stack seismic inversion.which synthesizes three reservoir petrophysical parameters(porosity,water saturation,shale content)to construct reservoir fluid phase,using the statistical rock physics model to characterize the relationship between elastic impedance and reservoir fluid phase,combining the Monte Carlo simulation techniques and apples the Expectation Maximization Algorithm to estimate reservoir fluid phase posterior probability distribution in the framework of Bayesian theory,and then we ultimately finishes reservoir fluid phase inversion;Finally,we studied a predicted method of TOC in shale gas reservoir with pre-stack seismic inversion,firstly,we made some maps about the intersection between TOC,elastic parameters and physical parameters,finding the best parameters for linearity with TOC,establishing the relationship between TOC and this parameter.Secondly,we reference to reservoir fluid phase inversion to achieve the inversion of TOC in shale gas reservoir.The above inversion methods had been processed by models and the actual data,the results are relatively accurate and credible.Those methods can be used to evaluate the hydrocarbon content of shale gas reservoirs and prove its usefulness.