Numerical electric breakdown model of heterogeneous granite for electro-pulse-boring

Zhu, Xiaohua; Luo, Yunxu; Liu, Weiji; Hu, Hai; Chen, Mengqiu

doi:10.1016/j.ijrmms.2022.105128

Cited by 29 publications

(23 citation statements)

References 42 publications

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“…The magnitude of conductivity is the most essential element impacting the conduction of the current, so we disregard the changes of other parameters in this process and focus on the state change of conductivity. According to the research of Zhu et al [ 18 ], when the field strength of the internal portion of the rock reaches the breakdown field strength, the electrical properties of this portion of the rock begin to change from resistance to conductor, and the conductivity at the channel can reach 1e6 at this point. Based on this occurrence, we graphically depict the conductivity change process as shown in Figure 2 .…”

Section: Analysis Of the Mechanism Of Rock Fracturing By High-voltage...mentioning

confidence: 99%

“…In the simulations investigated, both the type of hard rock and the distance between electrodes can be used as variable parameters to determine the effect of the relevant parameters on hard rock fragmentation. Table 2 [ 18 ] lists the material parameters of the electrodes and the insulating media surrounding the electrodes.…”

Section: Model Simulationsmentioning

confidence: 99%

“…Table 3 shows the basic parameters of the rock selected for our paper [ 18 ]. The effect of parameters such as conductivity and relative permittivity on the formation of plasma channels is investigated.…”

Section: Model Simulationsmentioning

confidence: 99%

“…Most models are developed for insulators; therefore, they are unsuitable for non-homogeneous media such as rocks. Neglecting the influence of electrical structure parameters on the breakdown path of rock media, Zhu et al [ 18 ] developed a coupling between the electric breakdown process and the circuit structure parameters by controlling the circuit current and the loading voltage in the current field controlled by the circuit. Cho et al [ 19 ] studied the high-voltage electric pulse under the rock fracture process and concluded that the fracture effect of high-voltage pulse discharge on rocks is caused by dielectric breakdown-induced body forces.…”

Section: Introductionmentioning

confidence: 99%

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The Utilization of a Coupled Electro-Thermal-Mechanical Model of High-Voltage Electric Pulse on Rock Fracture

et al. 2023

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Our research proposes a unique coupled electro-thermal-mechanical model that takes electric breakdown and heterogeneity into account to show the mechanism of rock fracturing under high-voltage electropulses. Using finite element numerical software, the process of high voltage electrical pulse injection into the rock interior for breakdown is described, and the formation law of plasma channels during the electrical breakdown process is comprehensively analyzed in conjunction with the conductor particles present within the rock. On the basis of electrical, thermal, and mechanical theories, a coupled multi-physical field numerical model of rock failure under the action of high-voltage electrical pulses is developed, and a random distribution model is utilized to simulate the potential occurrence of conductor particles in the rock. Innovative numerical model indicates plasma channel creation in the rock-crushing process. Prior to the formation of the plasma channel, the temperature and stress are approximately 103 k and 10−2 MPa, respectively. Once the plasma channel is formed, the temperature and stress increase abruptly in a short time, with the temperature reaching 104 k and the stress reaching 103 MPa or higher. In addition, it is revealed that the breakdown field strength is the essential factor in plasma channel creation. The heterogeneity of the particles within the rock and the fluctuation in electrode settings are also significant variables influencing the creation of channels. The presented model contributes to a better understanding of the mechanism of rock fragmentation during high-voltage electrical pulses, which has substantial implications for oil exploration and mineral extraction.

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Section: Analysis Of the Mechanism Of Rock Fracturing By High-voltage...mentioning

confidence: 99%

Section: Model Simulationsmentioning

confidence: 99%

Section: Model Simulationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Utilization of a Coupled Electro-Thermal-Mechanical Model of High-Voltage Electric Pulse on Rock Fracture

et al. 2023

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“…The breakdown process of high‐voltage electric pulse rock breaking is accompanied by drastic changes in voltage and current [ 21,22 ] ; when the plasma channel is formed, the corresponding current value of the high‐voltage electric pulse is 1 kA. [ 23 ] The current flows through the plasma channel and increases continuously, which will lead to a homoeopathic increase in magnetic field strength. [ 24 ] A previous study [ 25 ] found that forming a plasma channel produces an electron avalanche phenomenon when there is a large amount of charge in the plasma channel.…”

Section: Introductionmentioning

confidence: 99%

The effect of magnetic field on the electric breakdown trajectory of high‐voltage electric pulse rock breaking

Liu,

Zhou,

Zhu

2023

Contributions to Plasma Physics

Self Cite

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High‐voltage electric pulse drilling technology has the advantages of high rock‐breaking efficiency, low energy consumption for rock breaking, and good quality of well wall, which is a new and efficient potential rock‐breaking method. In this paper, we constructed a numerical simulation model of rock electric breakdown and realized the whole process of rock breaking and plasma channel generation by high‐voltage electric pulse. The results of the study showed that the change of magnetic field has a large influence on the formation of plasma channels inside the rock, and under the self‐magnetic field environment, the plasma channels inside the rock show branching, and the maximum penetration depth and maximum damage depth are higher than those under the non‐magnetic field environment. In the external magnetic field environment, the plasma channels gradually tend to develop “downward” (inside the rock), and the temperature distribution of the plasma channels inside the rock is more concentrated. In the presence of a magnetic field, the speed and degree of freedom of charged particles are limited. In an external magnetic field environment, the charged particles cause fewer particles to deviate, and the particles show a “downward” accumulation phenomenon. The research in this paper can provide certain theoretical and technical guidance for the development of electric pulse rock‐breaking technology and provide reference for the development and parameter optimization of electric pulse rock‐breaking tools.

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Experimental investigation on the rock breaking mechanism of electrode bit by high‐voltage electric pulses

Liu,

Zhang,

Zhu

et al. 2024

Contrib. Plasma Phys

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Because of the low rate of penetration (ROP) and high cost of traditional rotary rock breaking, it is important to explore some unconventional new rock breaking methods. High‐voltage electrical pulse (HVEP) drilling has attracted much attention because of its advantages such as environmental protection, good borehole wall quality, and high rock breaking efficiency. This paper independently designs and builds a complete indoor experimental platform of HVEP electric breakdown, and selects the self‐designed classic coaxial type and cross‐type electrode bits to carry out laboratory experiments of HVEP rock‐breaking, to truly reveal the rock breaking mechanism of HVEP drilling and further promote its industrial application. The influence of the anode structure of electrode bit, liquid insulation medium, drilling fluid circulation condition, and pulse voltage on rock breaking mechanism are investigated. The findings indicate that the bottom‐hole morphology of the rock sample is related to the electrode bit structure. The S‐type electrode bit has a certain discharge blind area, which is not conducive to the rock breaking of HVEP. With the increase of pre‐charging voltage, the effective discharge rate (EDR) of both electrode bits increases gradually, trending towards 100% as the pre‐charging voltage grows. Under non‐circulating working conditions, greater conductivity of liquid medium results in a lower EDR of electrode bits. In all kinds of liquid media, under low voltage (pre‐charging voltage <15 kV), the single pulse penetration depth (SPPD) under the non‐circulating working condition is larger than that of the circulating condition, in contrast, at a higher voltage (pre‐charging voltage >15 kV), the SPPD under the circulating condition is larger than that the non‐circulating condition. To further observe the generation of plasma channel and the rock damage characterization of HVEP, this paper also establishes a three‐dimensional numerical model of dynamic electrical breakdown of red sandstone to reproduce the generation of plasma channel, which can be mutually confirmed by indoor experimental results. The research results are essential for a deeper understanding of the rock breaking mechanism by electric pulse and for providing some theoretical guidance for the industrial application of electric pulse drilling technology.

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Numerical electric breakdown model of heterogeneous granite for electro-pulse-boring

Cited by 29 publications

References 42 publications

The Utilization of a Coupled Electro-Thermal-Mechanical Model of High-Voltage Electric Pulse on Rock Fracture

The Utilization of a Coupled Electro-Thermal-Mechanical Model of High-Voltage Electric Pulse on Rock Fracture

The effect of magnetic field on the electric breakdown trajectory of high‐voltage electric pulse rock breaking

Experimental investigation on the rock breaking mechanism of electrode bit by high‐voltage electric pulses

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