利用叠前振幅和速度各向异性的联合反演方法

A joint inversion method using amplitude and velocity anisotropy

基于振幅方位各向异性的裂缝检测方法对介质的各向异性程度敏感,分辨率高、易操作,但抗干扰能力差,对地震数据有较高的要求。为此,提出了利用叠前振幅和速度各向异性的联合反演方法。对于每一个微小时窗,将该时窗底界速度反演得到的各向异性梯度作为该时窗顶界振幅反演的约束,移动时窗进而得到一个反演体。模型测试和实际资料应用效果表明:(1)与叠前、叠后振幅各向异性反演相比,所提方法的反演精度最高。(2)在gs1井区,叠前速度各向异性反演结果与井裂缝曲线吻合较好,可作为振幅反演的约束,但较振幅各向异性反演的分辨率低,二者联合反演改善了速度反演分辨率低的问题。

The fracture prediction method based on amplitude anisotropy with high resolution is sensitive to the degree of medium anisotropy and easy to realize,but it is poor in dealing with noises and has high requirements on the quality of seismic data.For this reason,ajoint inversion method using prestack amplitude and velocity anisotropy is proposed.For each time window,the anisotropic gradient obtained from velocity inversion at the bottom of the time window is taken as a constraint of amplitude inversion at the top of the time window,and then an inversion volume can be obtained by moving the time window.Applications to model and real data show that:(1)compared with prestack and poststack amplitude anisotropy inversion,the inversion accuracy of the proposed method is the highest;(2)in the GS1 well block,the result of prestack velocity anisotropy inversion coincides with the fracture curve of the well,which can be used as a constraint of amplitude inversion,but the resolution of velocity anisotropy inversion is lower than that of amplitude anisotropy inversion.The joint inversion of prestack amplitude with velocity anisotropy can improve the resolution of velocity inversion.