Effect of electrode structure on high-voltage electric pulse rock fragmentation mechanism

doi:10.3969/j.issn.1006-6535.2025.03.015

Abstract

Abstract: In oil drilling operations, the challenges of cost, environmental protection, and efficiency in hard rock fragmentation urgently need to be addressed. High-voltage electric pulse drilling, with its high efficiency, eco-friendliness, low tool wear, and time-cost advantages in rock fragmentation, has become a research hotspot. To advance the understanding of the mechanism of high-voltage electric pulse fragmentation of heterogeneous hard rock, models of hard rock with different heterogeneity indices were developed using Particle Flow Code (PFC) software and Voronoi diagram. Additionally, a 2D electro-breakdown numerical model for single-pair electrodes fragmenting heterogeneous hard rock was established. The study focused on the effects of electrode structure, pulse discharge voltage, and rock heterogeneity on the high-voltage electric pulse heterogeneous rock fragmentation mechanism. The study shows that the plasma channel tends to initiate at local dielectric weak points, guiding its discharge path, closely related to the rock′s heterogeneity. The electrode tip′s discharge enhances the local electric field, improving rock fragmentation effect but minimally affecting plasma channel growth. Greater heterogeneity indices make hard rock more prone to electro-breakdown, significantly increasing fragmentation and penetration depth. Higher pulse discharge voltages promote deeper electric damage accumulation, favoring hard rock fragmentation. The study offers theoretical and technical support for applying electric pulse rock fragmentation in complex deep-formation well conditions.

Key words: high-voltage electric pulse, heterogeneous hard rock, plasma channel, electric breakdown

CLC Number:

TE928

ZHU Xiaohua, LIU Weiji, ZHANG Youjian. Effect of electrode structure on high-voltage electric pulse rock fragmentation mechanism[J]. Special Oil & Gas Reservoirs, 2025, 32(3): 126-132.

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