基于比值均方根的杨氏模量反演方法

Pre-stack inversion method of Young′s modulus based on the root mean square ratio

杨氏模量和泊松比是表征岩石脆性、评价储层可压性以及描述储层流体特征的重要参数,叠前地震反演是从地震数据中得到此类参数的有效手段.常规的叠前地震反演方法多使用Zeopppritz方程的近似式计算反射系数,近似式的误差影响了反演结果的精度.针对这个问题,推导了比值均方根形式的杨氏模量、泊松比和密度的Zoeppritz方程,并基于广义线性反演构建了杨氏模量和泊松比直接反演方法,有效地避免了使用近似式的局限性,提高了反演的精度.模型测试和实际资料试算结果表明:采用比值均方根形式构建的反演流程稳定,能够从叠前地震数据中获得可信的杨氏模量、泊松比和密度,提供了一种可靠的杨氏模量和泊松比直接反演方法.

Young′s modulus and Poisson′s ratio are two important rock parameters to characterize reservoir properties.Pre-stack seismic inversion is an effective tool to deterime such parameters from seismic data.Conventional seismic pre-stack inversion methods are mostly based on approximate expressions of the Zoeppritz equation.The error caused by this approximation would affect the accuracy of inversion results.To address this issue,we deduce the Zoeppritz equation in the form of the root mean square ratio of Young′s modulus,Poisson′s ratio and density.With this equation we develop the direct inversion method for Young′modulus based on a generalized linear inversion algorithm,effectively avoiding the limitation of approximate equation and enhancing the accuracy of inversion.Tests on a model and real data show that this inversion method based on the root mean square ratios is able to obtain credible Young′s modulus,Poisson′s ratio and density from pre-stack seismic data,which offers a reasonable direct inversion method for Young′s modulus and Poisson′s ratio.