Electrode structural effects on the mechanism of high-voltage pulse rock breaking

Abstract

In the oil drilling process, drilling costs account for more than 50% of total E&P costs. High-voltage electric pulse rock breaking is an economical and effective rock-breaking method that has received widespread attention. At present, there is not much research on the influence of the shape of the electrode tip on high-voltage pulse rock breaking. This paper establishes a system of equations that control the electric breakdown field based on the changes in the electric field inside the rock. Then, using this model, we conducted simulation and laboratory experiments to understand how rocks break under different conditions, such as load voltages, electrode spacing, and electrode tip shapes. The results show that the volume of broken rock is directly related to the loading voltage. The best loading voltage range is between 200 and 220 kV. Increasing the spacing between electrodes helps break more rock, but if the electrode spacing is too large, it's hard to make a hole in the rock, and the rock won't break. An electrode spacing of around 35 mm is the best. The shape of different electrode tips directly affects the high-voltage pulse breaking effect. Hemispherical electrode tips are less favorable for rock breaking, while oval electrode tips are the best. The laboratory experiments and simulations give the same conclusions and verify the applicability and correctness of our model. This study aims to help design high-voltage electric pulse devices.