Research Of Liquid CO2 Phase Transition Fracturing Technology Radius In Coal Seam

The Liquid CO2 Phase Transition Fracturing Technology is a new way to enhance coal mine permeability.Compared with tranditional fracturing technology,the Liquid CO2 Phase Transition Fracturing Technology is safe,convenient and environment protecting.It's an emergency problem to research the effective radial of the Liquid CO2 Phase Transition Fracturing Technology to provide the theoretical basis for promoting the technology.At first,this paper introduces the equipment of Liquid CO2 Phase Transition Fracturing Technology.The field test in No.13 Mine of Pingdingshan determines that the effective radial is 4.5m~5m under single hole fracturing condition according to the comparison of the gas drainage concentration and quantity before and after the fracturing.The connection between Liquid CO2 Phase Transition Fracturing Technology,a physical explosion phenomenon,and tranditional chemical explosion is built based on the TNT equivalent method.The mechanical mechanism of the technology is analysed,the result showed: the structure of coal mine is damaged because of the impact of high energy gas and stress wave.The occurring and progressing condition of the fissures in coal mine is analysed based on linear elasticity fracturing mechanics.The computational model of Liquid CO2 Phase Transition Fracturing Technology in LS-DYNA is built based on the TNT equivalent method,the computational result shows:the effective radius of the technology is 3.9m~4.5m,which is lower than the result in field test.The influence factors of the Liquid CO2 Phase Transition Fracturing Technology is analysed based on the computational model which has been established,the result shows: the stress wave decays faster in coal mine of larger elasticity modulus;the intial geostress restrains the spread of stress wave.