A shale gas reservoir has complex mineral components, bedding planes and micro-cracks, thus being of inherent heterogeneity and anisotropy. The roles of bedding planes in hydraulic fracturing performance have been deeply studied, but the effects of rock inherent heterogeneity induced by mineral components are not well understood. This paper establishes a two-dimensional particle assemblage model to investigate the impacts of mineral component heterogeneity on hydraulic fracturing treatments. The impacts of the mass fraction and elastic modulus of low-brittle minerals on fracture initiation pressure, breakdown pressure, fluid injection volume and fracture permeability are comparatively investigated through numerical simulations. It has been found that the mass fraction of low-brittle minerals is closely related to the critical pore water pressure while the elastic modulus of low-brittle minerals plays a significant role in fracture permeability. With the same hydraulic fracturing treatments, the shale gas reservoir with a large mass fraction of clay minerals could decrease the critical pore water pressure, while the shale gas reservoir with a low elastic modulus of clay minerals is conducive to increasing fracture aperture. The shale matrix heterogeneity induced by the fraction coefficient and micro-mechanical properties of clay mineral has a critical role in the fracture initiation and propagation as well as the variation of fracture aperture. This understanding of shale mineral composition can benefit the effectiveness evaluation on hydraulic fracturing and the morphology of fracture networks.

页岩气藏具有复杂的矿物成分、层理面和微裂缝，具有固有的非均质性和各向异性。层理面在水力压裂性能中的作用已被深入研究，但矿物成分引起的岩石固有非均质性的影响尚不清楚。建立二维颗粒组合模型，研究矿物成分非均质性对水力压裂处理的影响。低脆性矿物质量分数和弹性模量对起裂压力、破坏压力、注液量和裂缝渗透率的影响通过数值模拟进行了比较研究。研究发现，低脆性矿物的质量分数与临界孔隙水压力密切相关，而低脆性矿物的弹性模量对裂缝渗透率起着重要作用。在相同的水力压裂处理条件下，粘土矿物质量分数大的页岩气藏可降低临界孔隙水压力，而粘土矿物弹性模量低的页岩气藏有利于增加裂缝孔径. 粘土矿物的分数系数和微观力学性质引起的页岩基质非均质性对裂缝的萌生和扩展以及裂缝孔径的变化具有关键作用。这种对页岩矿物成分的认识有助于水力压裂的有效性评估和裂缝网络的形态。