Growth mechanism of high-voltage electric pulse rock breaking 3D plasma channel in drilling fluid environment

Abstract

High-voltage electric pulse rock breaking has excellent potential for exploiting deep geothermal resources. Numerous researchers have conducted experimental studies on this topic, particularly in rock mechanics, where the breakdown occurs. However, there has been limited scholarly research on drilling fluid. Therefore, the study focuses on the drilling fluid suitable for electric pulse drilling, considering the characteristics of electric pulse rock breaking, which differ from traditional rock breaking. The study focused on the impact of various drilling fluid parameters on the effectiveness of electric impulse rock breaking using red sandstone as the experimental material. This was investigated using the finite element method, and indoor electric rock-breaking tests were conducted in a drilling fluid environment. The results indicate that the plasma channel mainly grows in the permeable layer of the drilling fluid, resulting in shallow rock breaking depth in the drilling fluid environment. The pore permeated by drilling fluid guides the growth of the plasma channel. The higher the conductivity of the drilling fluid, the closer the ion channel of rock breaking by electric pulse is to the rock surface. This results in a smaller crushing volume and shallower damage depth, which is more detrimental to rock breaking by an electric pulse. The viscosity of drilling fluid can impede the breakdown to some extent. In this paper, the influence of drilling fluid parameters on electro-pulse rock-breaking technology is preliminarily studied, which has significant reference value for the selection of actual drilling fluid.