Study On Fracturing Fluid Flow And Proppant Migration In Wellbore-Fracture System

Multi-stage fracturing of horizontal wells is one of the important means to achieve efficient development of unconventional reservoirs.Multi-cluster and multi-branch complex fractures are formed in the formation due to multistage fracturing technology.However,there is competitive diversion phenomenon between fracturing fluid and proppant at the branches of inter-cluster fractures and intra-cluster fractures,and the proppant migration law is more complex.The conductivity of complex fractures is determined by the placement of proppant in them,so it is necessary to study the migration law of proppant in complex fractures.To solve the above problems,a field scale geometric model was established for numerical simulation to comprehensively analyze the flow of fracturing fluid in the wellbore and the migration and settlement of proppant in the fracture.This paper focuses on the study of multi-phase flow shunt law in wellbore,wellbore sand settling law,proppant placement law under different fracture propagation morphology,and compares the effects of different construction parameters,proppant and fracturing fluid types on proppant migration effect,so as to optimize the fracturing process parameters and improve the economic benefits of oil and gas wells.The results show that proppant deposition only occurs at the end of wellbore.The liquid phase distribution of each cluster in the well accords with the trend of variable mass flow.The distribution of proppant in multiple clusters of fractures is obviously off-heel and uneven among clusters of fractures.The number of fracture clusters,branch fracture order and fracture Angle all affect proppant migration.Through the sensitivity analysis of influencing factors,the field fracturing design was optimized,and the average stimulation effect of the three Wells in the block reached 34.7%,which has certain guiding significance for the optimization of fracturing parameters in the block.