一种基于3D复杂介质的弹性建模数值方法

储层中的裂隙会导致介质表现出各向异性.传统等效介质方法假定储层可以被等效成为横向各向同性介质,不适用于复杂裂缝储层的弹性等效建模和各向异性特征分析.本文在前人研究基础上,利用最小二乘方法开展3D复杂裂隙弹性等效数值模拟研究,并与常规等效介质理论方法进行比较,验证数值方法的精确性.数值方法不仅能有效避免Hudson理论和Eshelby-Cheng理论等解析方法在大裂隙密度条件下的参数估计误差,而且兼顾裂隙扰动作用对等效介质参数的影响.数值研究表明,数值方法能够较好地描述复杂裂缝介质的各向异性特征,为复杂裂缝储层地震波各向异性参数反演提供依据.

An elastic numerical method based on the 3D complex medium

Reservoir containing fractures exhibits the anisotropic characteristics. Thus the traditional effective medium theories assume an equivalence between the fractured sample and the transversely isotropic medium, however, which is not applicable for modeling and anisotropic analysis of complex fractured medium. Based on the previous studies, an effective numerical solution is developed, through a least squares procedure for the 3D complex medium containing cracks. We validate the accuracy of the numerical solution by the comparison with the traditional effective medium theories. The solution could not only avoid the parameter errors predicted by the Hudson and Eshelby-Cheng methods at the case of a larger crack density, but also take the crack interactions into account. Numerical study shows this solution can describe the anisotropic properties of the complex rock samples properly, thus provide appropriate seismic data for inversion of anisotropic parameters.