Experimental study on rock fracturing by using pulsed power technology

To improve the permeability of the oil or gas reservoir and enhance the production, the electric pulse discharge was often used which can generate high pressure pulse for the stimulation. To estimate the electro-hydraulic fracturing effects in the lab, a pulsed power supply with a stored energy of 40kJ was developed. The pulsed power supply was mainly composed of a high voltage high frequency charging supply, energy storage capacitors, a discharging switch and a discharging electrode. An optical fiber was used to isolate and transmit the high voltage signal between the high voltage unit and the control system. The test samples were made of cement and sand with a diameter of 0.48 m and a height of 0.5 m, and a vertical borehole with a diameter of 0.06m and a depth of 0.25mm was drilled in the center. Experimental results shown that large multi-fractures were generated, the maximum length of the fracture in the horizontal and vertical direction were 0.22 m and 0.32 m respectively.