Technology and research progress of plasma induced coal and rock cracking and antireflection

Efficient antireflection is the key to solve the exploitation of unconventional natural gas (coalbed methane, shale gas, tight gas, etc.) and reduce the probability of gas disaster accidents. Plasma based on physical discharge is characterized by high energy density, strong destructiveness, high temperature, reliable repeatability, controllable crack range, which has attracted great attention. This paper systematically reviews the research progress of plasma induced coal and rock cracking and antireflection technology from two modes of electrical crushing and hydroelectrical effect; the differences between electrical crushing and hydroelectrical effect are compared and analyzed from the perspectives of fracture principle, effect on micro pore and macro fracture structure of coal and rock mass; furthermore, the influence of plasma on coal permeability under in-situ conditions is studied; in addition, the application status of electric fracturing and hydro-electric effect in the field of fracturing coal and rock is summarized, and the bottleneck problem of plasma in the field of unconventional natural gas exploitation is pointed out, and a new idea of combined use of plasma and other antireflection measures is proposed.