Mechanism and Feasibility Evaluation of Laser-Assisted Rock-Breaking in Drilling Fluid Environment
摘要
Laser rock-breaking is an emerging technology by rapid heating, high energy, non-contact rock breaking. Its effectiveness is affected by various factors, particularly in deep drilling environments where rocks are hard, water-rich zones exhibit high water content, and drilling fluids are commonly used for lubrication in drilling construction. Investigating rock fracture and damage behavior under laser irradiation in liquid environments is essential for advancing laser-assisted rock-breaking applications. Laser attenuation and rock-breaking experiments were conducted under different liquid conditions to analyze the temperature distribution, fracture behavior, and mechanical damage of rocks under the laser irradiation. The results indicate that laser power is significantly reduced after passing through liquids, with drilling fluids exhibiting a greater attenuation effect than clear water. Laser-induced rock weakening is primarily driven by melting and fracturing, with the increase of laser power, the molten hole depth of saturated rock increases from 17.90 to 38.88 mm. When the laser power is 1304 W, the fracture volume reaches 2985.66 mm3, and the fracture area reaches to 23,235.53 mm2. Water primarily affects the strength of the rock through the softening action. The uniaxial compressive strength of the water saturated rock was significantly reduced after the laser irradiation, and the strength reduction rate increases with laser power, reaching up to 70.3%. Under submerged conditions, liquid hinders laser energy transmission, limiting the laser rock-breaking effectiveness. In addition, numerical simulations of rock temperature fields and crack propagation under laser irradiation were conducted, showing good agreement with experimental results. The results provide insights and practical references for the application of laser-assisted rock breaking technology in drilling engineering.