TI介质多波AVA方程及参数反演

Multiwave AVA equation and parameter inversion in TI media

1. 成都理工大学油气藏地质及开发工程国家重点实验室,四川成都610059;2. 中国石化胜利油田物探公司,山东东营257100

State Key Laboratory of Oil/Gas Reservoir Geology and Exploring, Chengdu University of Technology, Chengdu 610059, China

介质各向异性对多波振幅随着入射角的改变而变化 (AVA)有着重要的影响。根据Aki和Richards的方法, 建立了横向各向同性 (TI)介质分界面上的多波振幅特征方程, 由此方程可精确计算TI介质中平面波入射时的多波反射和透射系数, 并可建立TI介质岩性参数反演方程。理论模型和实际多波地震记录反演结果表明, 用各向同性介质理论的方法对TI介质进行参数反演将产生较大的误差, 而基于TI介质振幅特征方程的AVA反演不仅能得到高精度的地层参数, 还能得到地层的各向异性系数, 对裂隙型地层的研究有重要意义。

The anisotropy of a medium has a serious influence on the multiwave amplitude variation with incident angle. Multiwave amplitude characteristic equation has been deduced based on the method of Aki and Richards in the paper. The multiwave reflection and transmission coefficient of plane waves in TI media can be precisely computed and the parameters of a stratum can be inverted by the equation. Both theoretical modeling and real multiwave record computation have proved that the inversion based on isotropic theory would produce a larger error, whereas the inversion based on amplitude characteristic equation in TI media not only has a higher precision but also can obtain the anisotropic parameter which is important to the study of fractured formation.