Research on a Shock Wave Device with Pulsed Discharge for Shale Gas Stimulation

In order to further promote the application of pulsed discharge shock wave technology in production stimulation of shale gas wells, a shock wave device with pulsed discharge that could be used for downhole operations in shale gas wells was designed and developed. The device includes a ground power system and downhole energy storage and discharge systems. For favorable insulation performance and mechanical strength, the downhole part was enclosed in a stainless steel outer cylinder with an diameter of 102.0 mm. With a design maximum voltage of 10 kV and a maximum energy storage of 5 kJ, the device can repeatedly discharge more than 4000 times in a single downhole trip. Further, its energy storage method, load electrodes, and high-voltage capacitor were designed according to field characteristics and engineering requirements. Unblocking and rock sample fracturing experiments were carried out on the ground, and a downhole test was conducted in a oil well. Ground debugging experiments showed that the pulsed discharge shock wave device possessed high working stability, with effects of unblocking and rock fracturing. The downhole test revealed that liquid and oil production increased by 227% and 197%, respectively. Compared with those before construction, a favorable effect of production increase was achieved. Studies indicated that the device had high working stability and were able to achieve the favorable effects of unblocking and rock fracturing in oil wells. Further, it is also feasible to be applied to shale gas wells for stimulation, although the specific effect in shale gas wells needs further research.