横向约束分步叠前弹性参数反演

Lateral constraint two-step prestack elastic parameter inversion

针对部分实际地震资料信噪比分辨率不高、PP波反演结果不稳定、反演过程不适定等问题,提出了横向约束分步叠前弹性参数反演方法。首先利用Stewart的PP波和PS波反射系数近似式得到纵、横波速度信息;然后将获得的纵、横波速度作为已知背景项代入传统的Aki-Richards PP波三参数反射系数近似式,并在卡尔曼横向约束下进行AVO反演获得密度信息。理论分析及模型测试结果表明,横向约束分步叠前弹性参数反演改善了三参数AVO反演不稳定的问题,在一定程度上压制了噪声,提高了密度等参数的反演精度。实际资料测试结果表明,在纵、横波角道集同相轴匹配一致的前提下,横向约束分步叠前弹性参数反演能获得较好的应用效果,反演的密度和纵波速度剖面很好地反映了储层特征。

Partial seismic data is usually characterized by low signal-to-noise ratio and low resolution,and simultaneously the unstable inversion results and ill-posed inversion process occur in PP wave inversion.Focusing on these problems,we propose a lateral constraint two-step prestack elastic parameter inversion.First we obtain PP and PS wave velocity with Stewart's PP and PS wave reflection coefficient approximation.Then we substitute the calculated PP and PS wave velocity into the Aki-Richards's three parameters PP wave inversion approximation and calculate density information under the constraint of Kalman filtering algorithm.Results of theoretical analysis and model test show that the lateral constraint twostep prestack elastic parameter inversion overcomes the unstable problem of three-parameter AVO inversion,suppresses noise to some extent,and enhances parameter inversion accuracy,such as density.Real data tests indicate that the proposed elastic parameter inversion can obtain better results,PP and PS waves angle gather events match very well,and the density and PP wave velocity show clearly reservoir characteristics.