EXPERIMENTALSTUDYON INFLUENCING FACTORS OF FRICTION RESISTANCE COEFFICIENT OF N2 FOAM FRACTURING FLUID IN LOW PERMEABILITY SHALE RESERVOIR

摘要

The friction resistance coefficient of N2 foam fracturing fluid in low permeability shale gas reservoirs is large,resulting in the issues in the low permeability reservoir fracturing and reduced sand carrying performance.Based on low permeability shale reservoir conditions,the experimental device for measuring the friction resistance coefficient of the N2 foam fracturing fluid is designed and the effect of the N2 mass fraction,system temperature,system pressure and fracturing fluid flow rate on the friction resistance coefficient of the low permeability shale reservoir is studied.The research shows that the friction resistance coefficient of ABT cross-linked N2 foam fracturing fluid is only 1.6 under the conditions (a 35MPa,80°C,60% nitrogen mass and 2.2 m-s-1),which is far lower than 8.2 for ordinary guar gum fracturing fluid.The increase in system temperature,N2 mass fraction and fracturing fluid flow rate decrease the friction resistance coefficient of N2 foam fracturing fluid,and the friction resistance coefficient of fracturing fluid gradually increases with the increase of system pressure.Among the four factors,the system pressure has the least influence on the friction resistance coefficient of the N2 foam fracturing fluid,while the mass fraction of N2 has become the largest factor affecting the friction resistance coefficient.Exploring factors and solutions that can significantly reduce the friction resistance coefficient of fracturing fluids have important reference and application significance for the fracturing efficiency of low permeability shale reservoirs and the development of N2 foam fracturing.