Hydraulic fracturing of horizontal wells is essential for pore-type tight sandstone gas reservoirs in central Sichuan, where fracture conductivity is primarily controlled by proppant transport and placement. However, proppant migration in fractures is a dense granular flow process that remains insufficiently understood at the engineering scale. In this study, a three-dimensional solid–liquid Eulerian multiphase flow model is used to simulate the dual-particle-size proppant transport in tight sandstone gas reservoirs. Numerical simulations are conducted for both a single main fracture and a wellbore–fracture system to investigate the effects of the pumping rate, fluid properties, and proppant concentration on transport and placement behavior. The results show that increasing the pumping rate, fluid viscosity, and the proportion of fine proppant promotes more uniform proppant placement, with fluid viscosity exerting the dominant influence on proppant suspension capability. For proppants within the same mesh size range, size segregation occurs during transport: fine particles preferentially accumulate in the lower distal region of the sandbank, whereas coarse particles are more uniformly distributed within the sandbank. In the wellbore–fracture model, proppant initially accumulates in the short middle fracture, later shifting to the heel fracture, with similar placement volumes in the middle and toe. Step pumping leads to reduced proppant accumulation near the wellbore while maintaining similar placement in other regions. These results demonstrate the capability of the dual-particle-size Eulerian approach to capture engineering-scale proppant transport mechanisms and provide guidance for optimizing pumping strategies in hydraulic fracturing.
Zhou et al. (Sun,) studied this question.