叠前AVA岩性参数反演方法及精度分析

以VTI介质振幅特征方程为基础,研究了基于波形的多波多参数叠前AVA岩性参数反演方法。该方法利用动校正后的CMP及CCP全部角道集,建立多波多参数联合反演方程,进而求解出目的层段的岩性参数。以多个理论模型为例,对反演方程的建立、求解、抗噪能力以及P-P波单分量、P-SV波单分量、P-P与P-SV波联合反演的结果及精度进行了分析研究,结果表明,利用中心差分法建立反演方程误差最小;带阻尼的最小二乘QR分解(LSQR)法求解方程的精度和效率最高;多波联合反演结果最优,其反演结果的精度和抗噪能力都最强。对某地区储层模型正演的多波数据及实际多波资料分别进行了联合反演,获得的目的层段纵、横波速度及密度参数较好地反映了反演方法的有效性。

Pre-stack AVA lithologic parameters inversion and its precision

In terms of amplitude characteristic equation of VTI media,multi-wave & multi-parameter pre-stack AVA lithologic parameter inversion based on waveform was studied.The method utilizes all the CMP and CCP angle gathers after NMO to build multi-wave & multi-parameter joint inversion equation and calculate the lithologic parameters of interval.Taking several theoretical models as example,we analyzed the establishment,computation and anti-noise ability of inversion equation,studied the result and its accuracy of P-P wave single-component inversion,P-SV single-component inversion,P-P and P-SV wave joint inversion.The result indicates that the error of establishing inversion equation by central difference method is least,the accuracy and efficiency of LSQR method for resolving equation is highest,and the multi-wave joint inversion has best accuracy and anti-noise ability.Joint inversion was carried out both on the forward modeling and actual multi-wave data,and the inverted P-wave velocity,S-wave velocity and density of interval can well reflect the feasibility of the method.