Numerical study on rock breaking mechanism of supercritical CO2 jet based on smoothed particle hydrodynamics

Abstract

Supercritical carbon dioxide (Sc-CO2) jet rock breaking is a nonlinear impact dynamics problem involving many factors. Considering the complexity of the physical properties of the Sc-CO2 jet and the mesh distortion problem in dealing with large deformation problems using the finite element method, the smoothed particle hydrodynamics (SPH) method is used to simulate and analyze the rock breaking process by Sc-CO2 jet based on the derivation of the jet velocity-density evolution mathematical model. The results indicate that there exisits an optimal rock breaking temperature by ScCO2. The volume and length of the rock fracture increase with the rising of the jet temperature but falls when the jet temperature exceeds 340 K. With more complicated perforation shapes and larger fracture volumes, the Sc-CO2 jet can yield a rock breaking more effectively than water jet, The stress analysis shows that the Sc-CO2 rock fracturing process could be reasonably divided into three stages, namely the fracture accumulation stage, the rapid failure stage, and the breaking stabilization stage. The high diffusivity of Sc-CO2 is identified as the primary cause of the stress fluctuation and W-shaped fracture morphology. The simulated and calculated results are generally in conformity with the published experimental data. This study provides theoretical guidance for further study on Sc-CO2 fracturing mechanism and rock breaking efficiency.