An investigation into proppant transport in a tortuous fracture during supercritical CO2 fracturing

In this paper, laser topography scanning technology is used to extract the fracture morphology after supercritical CO2 fracturing to generate a tortuous fracture model. Then a supercritical CO2 slurry flow model is established based on CFD-DEM coupling method, and the proppant transport in the tortuous fracture is simulated. The flow and proppant transport characteristics of supercritical CO2 slurry in tortuous fractures were analyzed, and the effects of injection velocity, injection temperature and injection pressure on proppant transport and distribution in tortuous fractures were investigated. The results show that the flow of supercritical CO2 slurry in tortuous fractures forms curved dominant channels compared to planar fractures, and the formed proppant dune is not uniformly distributed within the fractures. Low injection velocity in tortuous fractures is more likely to cause sand plugging, and increasing the injection velocity can weaken the effect of fracture structure on proppant transport. Low injection temperature and high injection pressure facilitates the transport and distribution of proppant in tortuous fractures. The results of the study contribute to an in-depth understanding of the flow behavior of supercritical CO2 slurry in tortuous fractures.