中文摘要：

针对页岩脆性各向异性特征的研究相对薄弱,亟待发展与之相应的页岩储层脆性研究。为实现页岩脆性指数的表征,基于多尺度建模思想,引入各向异性元依次建立纳米级多孔黏土颗粒、亚微米级富有机质黏土颗粒和微米级干岩石骨架,并综合考虑吸附气、束缚水等影响因素,改进了常规基于DEM理论及Gassmann理论的建模流程,建立了页岩储层等效介质模型并实现了弹性参数的表征。然后,引入方位角的影响,依据Bond变换推导得到了杨氏模量、泊松比等脆性指数各向异性表达式,实现了以等效介质模型弹性模量为参数的脆性参数表征。最后,总结了页岩储层脆性的各向异性特征以及页岩储层脆性对矿物组分的敏感性,发现平行于储层走向且垂直于层理方向上的脆性是垂直于储层走向且与层理45°夹角时的2.5倍;同时,脆性对石英的敏感强度约为黏土的2倍。该特征研究可以为储层脆性预测及水力压裂方案设定提供参考依据。

英文摘要：

Since the study of the brittleness anisotropy for shale rocks is relatively rare,it is necessary to study the corresponding brittleness characteristics of the shale reservoir. Therefore,the authors construct an effective medium model to link elastic properties and brittleness index of shales to complex constituents and specific microstructures. Based on upscaling modeling,the authors sequently construct the nano-porous clay composite,submicron organic-rich clay composite and micron dry rock matrix by introducing clay particles. In consideration of the factors such as bound water and adsorbed gas in nanopores,the authors construct an effective medium model of shale reservoirs to characterize the elastic parameters,which improves the construction process based on DEM and Gassmann theory. Then,the anisotropic expressions of Young＇s module and Poisson＇s ratio based on elastic modulus parameters are derived by using the transition matrixes M and Bond conversion. Finally,the anisotropy features of shale rock＇s brittleness and the seismic response are summarized with different mineral constituents. Brittleness analysis shows that the brittleness in the direction that is parallel to the strike and perpendicular to the bedding is 2.5 times that perpendicular to strike and inclined to bedding at a 45 degree and the rock brittleness has increased,which suggests that the rock is more likely to fracture with increasing quartz content and decreasing clay content. These results provide a reference for predicting reservoirs＇ brittleness and designing hydraulic fracturing.