Numerical Study on Equilibrium Sand Partitioning of the Horizontal Well Multi-cluster Fracturing Technology

Multi-cluster fracturing technology of horizontal wells is the main technical means for the effective development of shale reservoirs. To obtain effective conductivity for each cluster, pumping parameters should be optimized to improve the non-equilibrium sand partitioning between clusters. Based on the computational fluid method, the Eulerian two-phase particle flow model was established. The sand partitioning law of multiple clusters in the wellbore and fractures was studied. The effects of different pumping rates, different proppant sizes and different slurry viscosity were analyzed. The results show that increasing the pumping rate is an effective means to improve the balance of sand partitioning between clusters. The increase in pumping rate can increase the sand inflow of toe clusters and improve the proppant placement in the direction of fracture height. In the case of 6 clusters in a single stage, at least 3 ~ 4 m3/min of pumping rate should be allocated to a single cluster. Appropriately increasing the viscosity of the slurry fluid can weaken the proppant settlement and increase the vertical proppant height in the fracture. Pearson correlation analysis shows that the pump rate has the greatest influence on the equilibrium sand partitioning of each cluster, followed by particle size and viscosity. In the actual fracturing operation process, it is suggested to increase the pumping rate and use the smaller size proppant under the safety operation conditions to obtain hydraulic fractures with high conductivity.