## 1 _Article_
###### Abstract
[4] reported experimental work to investigate the effect of different parameters on rock behavior under shock wave loading. The authors used purpose-built plasma discharge equipment to conduct experiments on different rock types. They observed that the energy required to create fractures increases as the confining stresses on rock samples increase. A further increase in the discharged energy generates more and longer fractures. [PERSON] et al. [5] used an experimental approach to study the feasibility of plasma stimulation on permeability change. They applied single and multiple shock waves of small magnitude and imaged the rock sample with computer tomography (CT) scanning to evaluate permeability enhancement. They observed that the permeability in the region near wellbore is improved even if the discharge energy is too small to create visible cracks, and repetitive discharges creates micro-cracks that increase the permeability by up to three orders of magnitude around the wellbore and deeper inside the formation. [PERSON] et al. [6] used two-dimensional simulated shale cases to study the effects of in situ stresses, the peak load, rock strength level, and rock tensile strength on rock behavior. In addition, they discussed the effects of peak load and rise time on fracture geometry and wellbore integrity. Key parameters that trigger ductile/brittle transition were also studied. [PERSON] et al. [7] performed experimental and numerical studies of shock wave fractures for single and repetitive loading. The results show that repetitive loading can be more effective than single loading, as it creates macroscopic, long cracks on the rock sample with less damage around wellbore. They also showed that the degraded loading mode of repetitive shocks may contribute better to crack density than upgraded loading. In addition, they developed a fitting method of the time-domain pressure/loading signal of a plasma reaction. [PERSON] et al. [7] conducted an experimental and numerical study to investigate the cumulative effect of cyclic loading on cement samples, showing that there are three zones created in the tested samples (crushing zone, crack zone, and elastic zone). These three zones can be controlled by adjusting the shock wave loading conditions. They proposed a methodology to minimize the crushing zone and maximize the crack zone. [PERSON] et al. [8; 9] investigated the impact of shock waves on permeability and porosity improvement in cement and coal rock samples. They used X-ray CT scanning (North Star Imaging Inc., Rogers, MN, USA) to examine the cracks length and density in the tested specimen. [PERSON] et al. [10] presented experimental evaluation of permeability increase in cement samples by the application of single and multiple shock waves. [PERSON] et al. [11] used small hollow cylindrical samples to evaluate the increase in intrinsic permeability of rock to gas by shock wave applications. They found that the energy threshold, above which an increase in permeability is observed, increases as the confining stresses on rock sample increases. The intensity of stress loading generated by a plasma reaction can be affected by different parameters in the implementation setup. [PERSON] et al. [12], [PERSON] et al. [13], and [PERSON] et al. [14] investigated the use of metal fusible wires and energetic explosives in the discharge gap between electrodes to increase the intensity of a shock wave. [PERSON] et al. [15; 16] investigated the distance between electrodes to maximize the efficiency of a shock wave (transfer from electrical energy to mechanical energy), and they discussed the effect of the plasma channel length on the intensity of a shock wave. [PERSON] et al. [17] studied the effect of the discharge modes on the peak intensity of a shock wave in water. And their work showed that the supersonic breakdown mode generates higher shock wave intensity and gives better efficiency than the subsonic mode. [PERSON] et al.