Study on the Dynamic Sand Carrying Capacity and Large - Scale Physical Simulation Cracking Performance of Medium and Low Viscosity Slick Water

The dynamic sand carrying capacity and large-scale physical simulation cracking performance of slick water with different viscosities and different types of drag reducing agents were studied, which provided theoretical basis for the optimal design of slick water formulation, In this paper, the dynamic sand carrying capacity and large-scale physical simulation cracking performance of conventional partially hydrolyzed polyacrylamide and hydrophobically associating polymer slick water were studied by using a visual plate dynamic sand carrying capacity test device and a true triaxial large-scale physical model crack initiation test device. The test results showed that the sand equilibrium bank height and slope angle formed by the medium viscosity slick water were relatively small, but the time to reach equilibrium was relatively longer; the sand equilibrium bank height and slope angle formed by the hydrophobic association polymer slick water were both larger than by conventional partially hydrolyzed polyacrylamide slick water at the same viscosity; the fractures formed by hydrophobically associating polymers slick water turned during the extension process, which is more conducive to the generation of branch fractures and unevenly distributed natural fractures in the core with the low viscosity; the extension speed of the fracture formed by the conventional partially hydrolyzed polyacrylamide slick water with the medium viscosity was slow, but the fractures were asymmetrical and had a certain angle of turning. In contrast, the fractures formed by the hydrophobic associating polymer slick water were relatively simple; increasing the displacement was helpful to create a complex fracture network at the same viscosity, and the fracture propagation pattern was determined by the displacement and the stress difference between fractures. These results can provide theoretical support for the on-site selection of slick water viscosity and drag reducing agent type.