AVO Inversion Based On Spatial Variation Of Reflector Constraints

Pre-stack seismic data contains abundant stratigraphic information and inversion method is stable and reliable,so Pre-stack AVO inversion is widely used in reservoir prediction.Reservoir parameters has heterogeneity,and the conventional pre-stack AVO inversion in order to improve the efficiency of the inversion,often ignores it.Therefore,under the framework of bayesian inversion,combining with the reflector constraint model,adding space-variant covariance matrix to the objective function,considering the change of lateral reservoir parameters influenced on inversion,we can improve the precision of reservoir prediction.This paper starts from the basic theory of pre-stack AVO inversion,introduces the Zoeppritz equation and the approximate equation,and analyzes the parameter sensitivity of commonly used approximate equation.According to pre-stack bayesian inversion theory framework,combining the likelihood function and the prior distribution,calculating the posterior probability distribution of the parameters,then building the inversion objective function.Because conventional pre-stack AVO inversion ignored the objective interval lateral variation of parameters,in order to improve the reliability and precision of inversion,this paper considered the reflector constraint item,by joining space-variant covariance matrices in the objective function to build he objective function which is reflected reservoir lateral variation.the model trial comparison showed that pre-stack AVO inversion method which based on space-variant reflector constraints can improve the accuracy of lateral reservoir identification.Seismic data often has problems such as dynamic correction stretching,tuning effect and strong reflector that influenced the recognition of target stratum.In order to have a better pre-stack inversion,we need to preprocess the seismic data,such as Residual move-out correction,Scale decomposition to tuning method and strong reflector recognition method based on matching pursuit.Space-variant reflector constraint AVO inversion showed that because considering the reflector constraints and space-variant covariance matrix,the identification of reservoir fluid on the vertical alignment is the same as the logging data.At the same time,analyzing the fluid factor slice,we known that the transverse distribution of reservoir is same as the drilling data,which prove the accuracy and reliability of the method.