Pre-Stack Seismic Fluid Indicator Inversion

Prediction of reservoir pore fluid is one of the important stages of seismic exploration.Fluid indicators are crucial parameter to describe hydrocarbon-bearing zones.Pre-stack AVO technology is a useful tool to obtain fluid factor from pre-stack seismic data directly.But there are some errors for most conventional AVO inversion method are based on AVO linear approximations and consider less about the influence of high order terms.Fluid impedances can be obtained from pre-stack seismic data directly by pre-stack fluid impedance inversion method.But it will reduce the certainty of inversion when using P-wave information only for considering less about the sensitivity of the S-wave to the lithology.In this paper,in the first,based on Zoeppritz equation and elastic porous media theory,the high order Russell fluid factor AVO approximations and Russell fluid impedances are deduced.Then,Series inversion theory and Bayesian theorem are introduced to build pre-stack no-linear AVO inversion method and pre-stack joint fluid impedance inversion method.At last,the high sensitivity fluid indicator Russell impedance factor is computed by combining the inverted Russell fluid factor and Russell fluid impedance.The results of model and actual data tests show that Russell fluid factor has higher sensitivity to the change of pore fluid.Pre-stack no-linear AVO inversion method has strong appearances in accuracy and noise immunity based on high order AVO approximations.Pre-stack joint fluid impedance inversion method can provide more information about the reservoir.Russell impedance factor can reduce the influence of lithologic change and improve the identification accuracy of pore fluid.