Geological adaptability of deep CBM U-shaped staged fracturing horizontal well in the south block of Yanchuan

The permeability of deep coal seam is generally poor, while the low production efficiency of fractured straight well is not ideal, therefore, the fractured U-shaped horizontal well development has been carried out and achieved good results. Geological evaluation must be carried out before the test to optimize the area suitable for U-shaped horizontal well. The main geological influence factors of the productivity of the fractured horizontal well are resources controlled by a single well, permeability and desorption difficulty, in which the resources controlled by single well are affected by the gas content and the thickness of the coal seam, and the permeability is related to the burial depth of coal seams and the characteristics of structural development and the degree of coal structure development. The permeability of broken coal is relatively good. Then, on the assumption that the adsorption performance is constant, the numerical simulation method was used respectively. The gas production of fractured horizontal wells with different permeability, gas content and thickness of coal seam was simulated. The simulation results show that the gas production of fractured horizontal well is positively related to permeability, gas content and thickness of coal seam. Finally, based on the evaluation of economic benefits, the geological conditions for the development of fractured horizontal well were identified as permeability > 0.25×10^-3μm², the gas content > 12.3 m³/t, the thickness of coal seam > 2.9 m. The geological suitability evaluation standard has been widely applied in the field, and has received good development benefits.