Sliding sleeve friction modelling and verification for infinite fracturing in horizontal wells

During sand fracturing in horizontal well, large displacement and high sand ratio fracturing fluid may easily cause strong erosion attack on inner surface of sliding sleeve and outside surface of switching tools, which will greatly reduce the service life of the tools and affect safe and effective constrution on site. In line with the above actual working conditions, an experimantel pipe string structure of tool series type and preliminary experimental design were established, and a mathematical model for in-string fluid friction was built. Research result shows that, if sand pump is double cascade connected and then parallel connected, it can both meet the requirement of displacement needed by the experiment and can provide the pressure head which can balance the fluid friction loss between the pipelines. The experimental scheme was perfected and the erosion attack experimental table was set up which satisfied the experimental requirements. When flow rate was 4.75 m3/min and there were two orifices on sliding sleeveⅡassembly, the overall pressure head of the pipingline is about 48.82 m. So the experimental result meets design requirement. Meanwhile, the theoretical calculation of friction loss is about 48.44 m, almost the same as the experimented friction loss, indicating that the theoretical model has high accuracy.