Research On Underground Hydraulic Fracturing Technology In Low Permeability Coal Seam

For the current difficult problems of the gas control in the low permeability coalseams, this thesis has theoretically analyzed the conditions, basic forms anddevelopment of crack propagation under the hydraulic fracturing action, and clarifiedthe crack propagation law and the permeability-increasing mechanism of undergroundhydraulic fracturing in the low permeability coal seam. By Introducing the concept ofelastic damage theory and the concept of homogeneity, it has established the hydraulicfracture extension model, and it has also studied the expansion of the undergroundhydraulic fracturing, the laws of coal displacement and stress variation; a set of specialequipment system for underground hydraulic fracturing is established, which is suitablefor the working environment of coal mine; the underground hydraulic fracturingtechnology for coal mines is determined, meanwhile the security system for themeasures of underground hydraulic fracturing technology is put forward. Through thefield tests it verifies the applicability, operability and safety of underground hydraulicfracturing and permeability-increasing technology in low permeable coal seams.