Permeability enhancement of coal by chemical-free fracturing using high-voltage electrohydraulic discharge

The new cracks induced in the coal samples were directional in nature. The fractures tended to more easily occur parallel to the direction of bedding plane (i.e., opening in the weakest direction), or on the bright bands of the coal, which are brittle and fragile compared to the softer and more elastic dull bands. Based on these observations, we are encouraged that EHD has potential as a method for reservoir stimulation and gas development for tight source rocks such as coal or shales.