Wall-retardation effect on proppant settling velocity in fractures: experimental study and model development

摘要

Accurate prediction of the particle settling velocity in parallel plates is important in predicting the transport distance of proppant in hydraulic fractures and improving the fracturing effect. However, the migration of proppant is retarded by the fracture wall and few studies have been conducted to investigate the wall-retardation effect of parallel plates on settling behaviors of particles. In this study, a total of 1080 tests were conducted to observe the settling behaviors of particles in parallel plates and analyze the effects of various factors on the wall-retardation factor, involving effective viscosity, and dimensionless diameter. Results indicate that the wall-retardation factor is a function of the dimensionless diameter and effective viscosity. Thus, a new model that is suitable for both Newtonian and Power-law fluids is developed to predict the wall-retardation factor between parallel plates. The proposed model is valid for the dimensionless diameter ranging from 0.01 to 0.9. The average relative error between measured and predicted wall-retardation factor is 3.40%. In addition, a predictive model of the critical dimensionless diameter is established to determine whether the proppants are retarded by the fracture. The results of this study may help field operators to further optimize fracturing performance.