Experimental Study on the Physical Simulation of Dynamic Sand Transport in Multi-Stage Fractures

To study the dynamic sand transportation and distribution patterns of proppant within fractures during hydraulic fracturing, an experimental device simulating sand transport in fracture systems with multi-scale was self-developed. This included carrying out an experimental study on dynamic sand transportation law and proppant height distribution patterns within fractures of different sizes under different frac fluid viscosity, proppant type, pumping flow rate and proppant concentration. The experimental results showed that the viscosity of frac fluid is the most influential factor followed by particle size of the proppant, proppant concentration and flow rate. The higher the viscosity of fracturing fluid, the less proppant settlement, and the lower and the gentler the settled proppant bank profile. This is more obvious in main fractures. The larger the particle size of the proppant, the more the settled proppant, the higher the settled proppant bank profile. It is more obvious in main fractures, too. Similarly, the higher the proppant concentration, the more the settled proppant, and the higher the settled proppant bank profile. This change is even more notable in branched fractures. The higher the flow rate, the slightly less the settled proppant. Further, it is almost the same in branched fractures. The research results will provide a theoretical basis for the optimization of frac fluid, proppant, and fracturing operation parameters as well as a formulating fracturing scheme.