Numerical investigation on grout spread and grouting parameter analysis in fracture with flowing water

Abstract

Grouting is crucial for oil and gas extraction as an economical and effective method for preventing subsurface water seepage in rock fractures. In this study, rough fracture surfaces were established based on the Synfrac program, and a modified Bingham model charactering the time-varying viscosity of grout was employed. The two-phase flows were numerically investigated using the level set method to capture the dynamic evolution of the interface by varying the parameters. Four types of grout spread and flow fields were analysed in the orthogonal simulation. The results indicate that the contact ratio α, grouting pressure P, diameter of the grouting hole b and water velocity vw have significantly influences the grout spread and sealing efficiency δ. The propagation pattern becomes irregular as the grout is continuously injected into the fractures owing to various parameters. Vortex zones emerge at the slurry-water interface, where dynamic water tends to be blocked in the fracture. The rapid increase in grout volume results in a longer spread distance and greater spread pressure. The diameter of the grouting hole and contact ratio have a greater influence on the grout volume. Compared with the grouting pressure, increasing the diameter of the grouting hole can appropriately improve the sealing efficiency of the slurry in the fracture. The volume reduction of water was calculated to provide a comprehensive understanding of the sealing efficiency of the grout under flow conditions. Finally, the relationship between the plugging efficiency and the four factors was obtained.