Mechanism of Single Proppant Pressure Embedded in Coal Seam Fracture

The strength and rigidity of proppant and coal are quite different. Proppant is easily embedded in coal, resulting in the decrease of fracture aperture and conductivity. The mechanism of proppant embedded in the coal fracture surface needs further study. In this paper, through theoretical analysis and experimental research of single proppant embedded, the proppant embedded law is analyzed from macro and micro aspects. The damage factor of coal surface is introduced, the damage model of the whole process of single proppant pressure embedded is established, and the mechanism of coal fracture surface embedded pit and cracks is revealed. The results show that, from the center of the contact surface to the outside, the surface failure forms of coal fracture are pressure failure, tensile-shear failure, and tensile failure. The proppant is embedded in the coal fracture surface to form four areas: central compaction area, layered fracture area, fracture development area, and original state area. During the energy release of proppant embedded in coal, the energy of proppant is released first and the energy of coal is released later. Greater than 3 times the contact radius, the influence of single proppant on the coal fracture surface can be ignored.