Objective Despite the adoption of various permeability enhancement technologies,the low permeability of coal reservoir has not been fundamentally improved for the development of coalbed methane(CBM)on the ground or the control of gas underground.New permeability Objective Despite the adoption of various permeability enhancement technologies, the low permeability of coal reservoir has not been fundamentally improved for the development of coalbed methane (CBM) on the ground or the control of gas underground. New permeability