Theoretical Analysis and Numerical Simulation of Laser to Rock

The rock-breaking characteristics and the influence factors of laser perforation are investigated in this study. A series of fiber laser perforation experiments on basalt, sandstone, and granite were conducted. Experimental measurements of rock failure morphologies and composition tests showed that the main surface features are thermal cracks and glazed layer formed by the melting and condensing of rock in laser perforation. It is also found that higher quartz content could help reduce the glazed degree of rock. Comprehensive results showed that the laser rock perforation is mainly formed by thermal fractures, the decline of molten pool, and the evaporating and splashing of the special melted rock components. The depth of rock perforation and SE usually increase with the laser irradiation time, while the ROP gradually decreases. With the increase of laser power, the perforation depth and ROP gradually increase, while the SE initially decreases and then increases indicating that there is an optimal power that maximizes perforation efficiency. It is believed that the strength of rock is the main factor affecting laser perforation efficiency, and the lower rock strength resulted in deeper perforation depth, higher ROP, and lower SE.

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Micro analysis of rock fracturing under the impact of high-temperature and high-pressure fluid

Pang,

Hu,

Yan

et al. 2023

Preprint

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To reveal the mechanism of high-temperature and high-pressure fluid thermal shock rock breakage and the formation mechanism of microcracks, this paper carried out an experimental study of supercritical (SC)-CO2 thermal shock rock breakage by using a self-developed hard rock true triaxial aerodynamic pulse fracturing experimental system and studied the micro-characteristics of different kinds of cracks after high-temperature and high-pressure fluid impact cracking by scanning electron microscopy. This study discovered three main actions in the process of rock breaking by SC-CO2 thermal shock. 1) The stress wave generated by thermal shock forms radial tensile stress and radial cracks during stress wave propagation and circumferential tensile stress and circumferential cracks during unloading. At the same time, spherical particles appear on the fracture surfaces of radial cracks and circumferential cracks; these particles are features of vertical and horizontal gullies. 2) The splitting action of high-temperature and high-pressure fluid further expands radial and circumferential cracks and promotes the generation of shear cracks (branch cracks). The fracture surfaces of branch cracks appear flat and smooth and have bedded and river shapes. 3) Collapse pits are formed by scouring. Although the collapse pits have different shapes and depths, all the pits are flat and smooth. The research results are significant for revealing the rock breaking mechanism of SC-CO2 thermal shock and play an important role in quantitatively controlling directional pre-cracking, hole layout parameter design, and crack type, size and complexity.

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Theoretical Analysis and Numerical Simulation of Laser to Rock

Cited by 3 publications

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Numerical simulation and experimental investigation on fracture mechanism of granite by laser irradiation

Numerical simulation and experimental investigation on fracture mechanism of granite by laser irradiation

Experimental Investigation on Hard Rock Breaking with Fiber Laser: Surface Failure Characteristics and Perforating Mechanism

Micro analysis of rock fracturing under the impact of high-temperature and high-pressure fluid

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