Research On Optimization Of Hydraulic Fracturing System Formed By Pickering Emulsion

Nowadays,the industry is being increasingly reliant on the advancement of fracturing fluids to achieve the best performance of shale reservoir stimulation.In order to solve the problem that the slickwater fracturing fluid is limited in sand carrying,Pickering emulsion is developed to act as a new fracturing fluid.Hitherto,the good conductivity of the Pickering emulsion fracturing fluid and the mechanism of its supporting cracks have been demonstrated.The main goal now is to optimize its performance of hydraulic fracturing.Firstly,the screening of solid particles and the formulation optimization of the whole system were carried out,and a base system was obtained for subsequent work research.Then the rheological properties of the base system and the friction test in the long pipeline were investigated,followed by the backflow performance and fluid loss performance evaluation and optimization.As results,the suitable cleanup additive and fluid loss additive were selected.Molecular simulation was carried out to explore the mechanism of the action between fracturing additives.Finally,the complete Pickering emulsion fracturing fluid system was combined with the real rock samples for performance analysis.The damage rate of Pickering emulsion fracturing fluid to the core was investigated,followed by the cracking ability and stabilizing shale tests.Through the above research methods,nano silica particles with mass concentration 2%were preferably used as the solid particles for Pickering emulsion.The particle size is about 50nm and the biodiesel was selected as the oil phase,the oil-water ratio was 4:6.Pickering emulsion is pseudoplastic fluid.Owing to its low friction in the long pipeline,there is no necessity to add drag reducer.Through the surface/interfacial tension and backflow performance tests,a well-behaved drainage system was 0.04%FY-F501+0.06%AOS,and the feasibility and mechanism of the system were demonstrated by compatibility evaluation and molecular simulation.The high temperature and high pressure and atmospheric pressure filtration experiments showed that the fluid loss additive CMC-3 had good fluid loss performance.Under this condition,the Pickering emulsion fracturing fluid system is superior to the traditional slick water and guar fracturing fluid.The damage rate of the fracturing fluid system to the core was obtained within a reasonable range.The complete system of Pickering emulsion fracturing fluids is:2%nanosilica,0.06%AOS,0.04%FY-F501,0.10%CMC-3,and biodiesel-water ratio to 4:6.The surface tension of this system is 35.53 m N/m,and the viscosity is higher at 170 s^-1 shear rate up to 130 m Pa·s.The seam-forming ability is better than that of slick water fracturing fluid and can stabilize shale cracks for a long time.