Numerical Investigation of Rock Breaking Mechanism With Supercritical Carbon Dioxide Jet by SPH-FEM Approach

Abstract

As a novel technology in the field of petroleum exploitation, rock breaking with supercritical carbon dioxide (SC-CO 2 ) has considerable social and economic benefits. To investigate the rock breaking mechanism under SC-CO 2 jet impacting in terms of mass and energy conservation, a fluid-solid coupling numerical model was established using smoothed particle hydrodynamics (SPH) method coupled with the finite element method (FEM). Jet movement feature and the stress distribution rule of impact target were obtained. Moreover, the space-time evolution of erosion cavity and failure process of elements were analyzed. The numerical research results are as follows: (1) the hybrid algorithm of SPH-FEM was effective for obtaining the numerical representation of rock breaking process under SC-CO 2 jet impacting, and the simulation results were in good agreement with the experimental data. (2) The asymmetrical distribution characteristics of monitored points caused the erosion cavity to deviate from the geometrical center of the target face. (3) Soft rock under SC-CO 2 jet impacting presented two failure forms: erosion and exfoliation. (4) The process of rock breaking with SC-CO 2 jet was as follows: when the jet came into contact with the target plane, the pressure stress on the mating face and shear stress on the contact edge dominated the evolution of initial compression-shear failure zone. Thereafter, the high diffusivity-driven SC-CO 2 penetrated into tiny cracks or pores near the failure zone, and strong air wedge effect caused tensile failure. With continuous high-speed impacting, the initial failure zone extended to a larger primary failure zone. Moreover, a few discrete failure zones were formed due to the high uncertainties of particles' motion trajectories, which mutually contributed to the main failure zone, and the erosion cavity was formed. When the jet became steady, quasi-static action was applied to the rock sample, and the erosion range expanded continuously.INDEX TERMS Jet impingement, numerical representation, rock fragmentation, supercritical carbon dioxide.

Composite rock-breaking of high-pressure CO2 jet & polycrystalline-diamond-compact (PDC) cutter using a coupled SPH/FEM model

“…As the CO 2 jet shows the feature of drastic volume expansion in the free field, the SPH method is well suited for its numerical modeling [21,22]. The SPH method, which is based on the interpolation theory, allows any function to be expressed at a set of disordered points which represents particle positions via smooth kernel function.…”

“…With the development of jet drilling technology, a large number of experts have carried out a lot of research on water jet rock breaking [16], SC-CO 2 jet rock breaking [17] and single PDC cutter cutting [18,19]. By using arbitrary lagrange eulerfinite element method (ALE-FEM) [20], SPH-FEM [21,22] and other coupled method, the simulation study of the jet rock breaking mechanism is carried out. However, there are relatively fewer researches on the composite rock-breaking of high-pressure CO 2 jet & PDC cutter, which would limit the development and application of CO 2 drilling in future exploitation.…”

Impact Pressure Characteristics of Carbon Dioxide Phase Transition Fracturing Technique

“…In recent years, scholars have conducted preliminary explorations on CDPTF, including CO 2 fractured coal body life cycle, crack propagation, − CDPTF vibration, energy distribution, etc. Among them, the impact pressure of CDPTF on the rock body is essential.…”

Experimental and numerical investigation of the fatigue behaviour and crack evolution mechanism of granite under ultra-high-frequency loading

“…For example, Hu et al [20] used LS-DYNA to study the rock fragmentation mechanisms when cut by a cutter and concluded that there are three fracture modes of rock breaking: forward slip, no slip and backward slip. Yang et al [21] investigated the rock-breaking mechanism under supercritical (SC)-CO 2 jet impacting based on the smoothed particle hydrodynamic finite-element method (SPH-FEM). Numerical results showed that there were two failure forms for rock under SC-CO 2 jet impacting presented: erosion and exfoliation.…”