<p>In the fluid injection stimulation process of unconventional reservoirs, proppants are frequently used to maintain the opening of fractures for economic resource recovery. Understanding proppant transport in rock fractures is important to constrain fracture geometry and inform fluid injection design. In this study, we establish a coupled CFD-DEM model to simulate the transport process of proppants in fractures. A systematic parametric study is performed to investigate the influence of injection parameters (proppant density and fluid viscosity) and fracture morphology (fracture tortuosity and fracture width). The flow field distribution and mechanical characteristics of particles (proppants) are analyzed, and the velocity change and spatio-temporal accumulation evolution of particles are examined, revealing proppant transport and laying mechanism. Our results show that proppants accumulate horizontally, forming layers over time when the proppant density and fluid viscosity are low in smooth fractures. On the contrary, proppants often accumulate vertically over time when the proppant density and fluid viscosity are high. When the sand-carrying fluid flows through tortuous fracture, fluid erosion occurs at tortuous corners, forming a sand bank depression. It is also noted that the fluid velocity increases at tortuous corners, implying that more particles could be transported in fractures with higher tortuosity.</p>