粘弹介质叠前四参数同步反演及应用

Prestack four-parameter synchronous inversion method based on viscoelastic medium theory and its applications

叠前地震资料中包含纵波速度、横波速度、密度和吸收衰减系数等弹性及粘弹性信息,其中吸收衰减属性对储层物性及流体性质尤为敏感。本文从粘弹介质精确Zoeppritz方程出发,基于介质分解理论通过公式推导及近似,建立了包含纵波速度、横波速度、密度和吸收衰减系数的纵波反射系数特征方程,利用贝叶斯反演框架,实现了叠前纵波速度、横波速度、密度、衰减四参数同步反演。模型与实际资料反演效果均表明了该方法的可靠性。该方法较好应用于胜利油田东部海上探区的油气识别,相比于常规弹性介质流体因子,四参数同步反演方法得到的吸收衰减系数能更准确地表征油气的分布。

Prestack seismic data contain elastic and viscoelastic information such as P-wave velocity,S-wave velocity,density and absorption attenuation parameters,among which absorption attenuation property is particularly sensitive to reservoir physical properties and fluid properties.Based on the accurate Zoeppritz equation of viscoelastic medium and the theory of medium decomposition,the authors established the characteristic equation of P-wave reflection coefficient including P-wave velocity,S-wave velocity,density and absorption attenuation parameters.Furthermore,under the constraint of Bayesian inversion framework,the simultaneous inversion of prestack four parameters was realized.The reliability of the method was verified by the trial of forward model.Finally,the method was applied to oil and gas identification in the eastern offshore exploration area of the Shengli Oilfield.Compared with things of the fluid factor based on elastic medium,the absorption and attenuation parameters obtained by the four-parameter simultaneous inversion method can more accurately characterize the distribution of oil and gas.