Abstract: During the proppant injection stage of hydraulic fracturing,fractures remain in a state of continuous propagation.To investigate the influence of fracture propagation on proppant placement,on the basis of previous studies,this paper used a physical simulation apparatus for proppant transport with dynamically variable fracture width.Using a single-factor analytical method,proppant transport simulation experiments were conducted under different branch-fracture opening times,different injection rates,different sand ratios,different fracturing-fluid viscosities and were compared with experiments conducted under fixed fracture conditions.The results show that fracture propagation exerts a significant influence on proppant placement.Compared with the results of fixed-fracture-width experiments,the horizontal decline rate of the equilibrium proppant-bank height reached 24.68%,and the increase rate of the distance to the leading edge of the proppant bank reached 45.09%.This difference decreased with increasing injection rate,sand ratio and viscosity.During the sand-adding stage of fracturing,targeted filling of branch fractures with proppant is conducive to improving proppant placement within fractures.During the early stage of proppant injection,pumping with a high injection rate,low sand ratio and high viscosity is favorable,whereas during the later stage,pumping with a high injection rate,high sand ratio and low viscosity is favorable.Alternating pumping is conducive to efficient proppant placement.This study reveals the influence law of dynamic fracture propagation on proppant placement and provides a theoretical basis for optimizing fracturing parameters and achieving efficient proppant placement.

Key words: proppant, hydraulic fracturing, fracture propagation, proppant placement, physical simulation