Multi-scale mechanics of submerged particle impact drilling

Particle Impact Drilling (PID) technology is highly efficient for exploitation of unconventional energy resources in extra-deep and ultra-hard strata. The multi-scale dynamic responses and fracture mechanics analysis of rock formations in drilling using the PID are discussed in this paper. Firstly, rock fracture experiments and penetration performance under submerged particle jet impact were conducted to analyze fracture mechanisms in macro-scale. Then, the rock constitutive relation model and damage model for the submerged particle jet impacts using the damage and failure theory and correlation analysis model were constructed. On this basis, multi-scale dynamic responses and nonlinear analysis of failure performance with submerged particle jet impact were conducted. Our results indicate continuous damage growth in macro-scale and radial cracks development in micro-scale when submerged particles impact the drilled formation in a process of creating a well.