Analysis of seepage law of power-law fluid in fractured media with different contact rates

Uranium ore is a critical strategic resource for nations. Sandstone-type uranium deposits, hosted in aquifers between coal seams During coordinated coal-uranium mining, the original fractures in sandstone frequently experience contact alterations under stress disturbances induced by the extraction of upper and lower coal seams Considering that in-situ uranium mining is inevitably affected by non-Newtonian fluid solution, in order to explore the seepage law of non-Newtonian fluid in sandstone fractures under contact disturbance, digital reconstruction is carried out based on the real sandstone surface formed by the Brazilian split. Numerical simulation was carried out on the flow of power-law fluid in fracture models with different contact rates. The coupling effect of contact rate and power-law fluid characteristics in pressure field and velocity field was explored, and the development law of groove flow and eddy under contact disturbance was demonstrated. The variation trend of the same cross-sectional area of flow direction on the cross-sectional pressure and velocity. The results indicate that the nonlinearity of the flow is enhanced with the increase of the contact rate. There is an obvious pressure division near the contact zone, and a smaller power-law index and a larger inlet velocity show a stronger pressure barrier effect. The groove between the contact zone is the fluid acceleration zone, and the small viscosity fluid is more sensitive to the acceleration effect of the groove, and it is easy to generate eddy on the back flow area, and the eddy area increases with the increase of velocity. The cross-sectional area of the fracture is inversely related to the seepage velocity of the fracture, and for the pressure distribution, the pressure and cross-sectional area are not monotonic, but there may be a rising region along the flow direction. The change of pressure curve is opposite to that of velocity curve, and the corresponding relationship increases with the decrease of contact rate, and the change of pressure curve lags slightly behind that of velocity curve. In addition, power-law fluids with different power-law indexes and inlet velocity have obvious difference in flow state under different contact conditions, which proves that the flow of power-law fluid is sensitive to contact area, power-law index and inlet velocity.