Experimental and numerical analyses of electro-pulse rock-breaking drilling
Experimental and numerical analyses of electro-pulse rock-breaking drilling
复制标题
电脉冲破岩钻进的实验与数值分析
DOI：
10.1016/j.jngse.2020.103263
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发表时间：
2020-05-01
影响因子：
--
通讯作者：
Chikhotkin, Victor
中科院分区：
文献类型：
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作者：
Li, Changping;Duan, Longchen;Chikhotkin, Victor
深井、超深井的电脉冲钻进具有广阔的市场前景。它使用可控的能源，而且没有污染。本文综述了高压短脉冲电源和EPB电极钻头的研究进展。针对电脉冲破岩钻头常见的同轴圆柱体结构，建立了仿真模型。研究了电极间距和高压电极形状对电脉冲破岩效果的影响。根据仿真结果确定了最大电极间距，并对高压电极的形状进行了优化。设计了45 mm间距和25 mm间距的电极钻头。利用电极钻头的实际结构尺寸和岩石物理参数，对采用这两种钻头尺寸的EPB进行了数值模拟。模拟表明，由于自然产生的气隙，岩石中的电场变形，这可以增强内部电场强度。在此基础上，研制了基于变压器式脉冲发生器的EPB实验系统。采用变压器油作为钻井液，钻进红砂岩。用25 mm和45 mm电极钻头在80kV电压下对砂岩进行电击穿，钻进直径分别为60 mm和100 mm。通过对EPB的模拟分析和实验研究，得出了EPB的有效工艺参数和规律，为实际应用中电极钻头的设计和钻井参数的选择提供了理论和实践指导。
The electro-pulse boring (EPB) of deep and ultra-deep wells has great market prospects. It uses controllable energy and is pollution-free. In this paper, research into high-voltage short-pulse power supplies and EPB electrode bits is reviewed. The simulation model was established according to the common coaxial cylindrical structure of the electric pulse rock breaking bit. The effects of the electrode spacing and the shape of the high-voltage electrode on the electric pulse rock breaking were then studied. According to the simulation results, the maximum electrode spacing was determined and the shape of the high-voltage electrode was optimized. The electrode bits with 45- mm spacing and 25-mm spacing were designed. Numerical simulations of EPB using these two bit sizes were conducted in which the actual structure size of the electrode bits and rock physical parameters were used. Simulation revealed an electric field distortion in the rock due to naturally-occurring air gaps, which can enhance the internal electric field strength. An experimental EPB system based on a transformer-type pulse generator was then developed. Transformer oil was used as a drilling fluid and red sandstone was drilled. Electric breakdown of sandstone by 25-mm and 45-mm electrode bits was conducted at a voltage of 80 kV, which produced drilling diameters of 60 mm and 100 mm, respectively. According to the simulation analysis and experimental research of EPB, the effective technological parameters and the law of EPB were obtained, which provided theoretical and practical guidance for electrode bit design and the selection of drilling parameters in practical applications.