Study On The Preparation And Performance Of Breaker And Temporary Plugging Agent For Fracturing

Fracturing technology is a key technology to increase the yield of lowpermeability reservoirs and realize the valuable development of shale oil and gas.Fracture breakers and temporary plugging agents play an indispensable role in fracturing technology.In response to the actual demand of Daqing Oilfield for fracturing liquid gel breakers and high-performance temporary plugging agents,this paper designs and develops alkaline,low-corrosive and highefficiency liquid gel breakers,45? low-temperature high-efficiency liquid gel breakers and-25? antifreeze.Type liquid gel breaker,as well as a temporary plugging agent for blastholes with a pressure of 60 MPa and a temporary plugging agent for a joint with a pressure of 40 MPa.The breaker is an important additive to ensure the smooth flowback of the fracturing fluid after the fracturing process.Aiming at the problems of inconvenient feeding of solid materials,difficulty in continuous and stable feeding,inaccurate metering,and incomplete low-temperature gel breaking,which existed in the fracturing process of 40-90? reservoir layer in Daqing Oilfield using potassium persulfate solid gel breaker,this article focuses on different pressures.According to the types of fracture fluids and different reservoir temperatures,the main agents of two liquid gel breakers have been designed and developed,which significantly improves the gel breaking effect and reduces the residues after gel breaking.It can be pumped on site to meet the requirements.Construction site requirements.According to the breaking effect of the main agent,comprehensively considering the various properties of the liquid breaker in use,it is selected through laboratory experiments and is suitable for the liquid breaker of the Daqing Oilfield fracturing system.The formula of high temperature liquid breaker is 10%alkali metal double salt containing potassium,sodium,sulfur and chlorine+0.05%breaking auxiliary Y-1+0-20%antifreeze T-1+0.2%corrosion inhibitor S-1,Low temperature auxiliary liquid gel breaker formula is 6%copper-rich alkali metal double salt+0-20%antifreeze N-1+0.4%corrosion inhibitor W-1+0.2%corrosion inhibitor W-2.The gel breaking experiments have proved that at 90?,0.1%WQ-1 high temperature liquid breaker can reduce the viscosity of guar gum fracturing fluid within 4 hours by 5 mPa·S,and the breaker fluid residue is less than 162 mg/L.The surface tension is 27.8 mN·m-1,0.2%addition amount can reduce the viscosity of the associative fracturing fluid within 6 hours to below 5 mPa·S,the breaker fluid residue is less than 66 mg/L,and the surface tension is 26.3 mN·m-1.Under the condition of 45?,0.2%WQ-2 low temperature auxiliary liquid breaker can reduce the viscosity of guar gum fracturing fluid to less than 5 mPa·S within 5 hours,the breaking residue is less than 36 mg/L,and the surface tension is 28.0 mN·m-1.45? associated fracturing fluid needs to be used in combination.The amount of breaker added is 0.8%WQ-1 high temperature liquid breaker+0.2%low temperature auxiliary liquid breaker,which can make the association pressure.The viscosity of the cracking fluid decreases below 5 mPa·S within 10 hours,the residue of the breaker fluid is less than 24 mg/L,and the surface tension is 27.5 mN·m-1.At 60?,0.15%WQ-2 low temperature auxiliary liquid breaker can reduce the viscosity of guar gum fracturing fluid within 5 hours by 5 mPa·S,the breaker residue is less than 36 mg/L,and the surface tension is 27.8 mN·m-1,0.6%WQ-1 high temperature liquid breaker+0.2%WQ-2 low temperature auxiliary liquid breaker can reduce the viscosity of the associative fracturing fluid to below 5 mPa·S within 4 hours,and the breaker fluid residue is less than 28 mg/L,the surface tension is 26.9 mN·m-1.Under the condition of 75?,0.15%WQ-1 high temperature liquid breaker can reduce the viscosity of guar gum fracturing fluid within 5 hours by 5 mPa·S,the breaker residue is less than 206 mg/L,and the surface tension is 27.9 mN·m-1,0.4%WQ-1 high temperature liquid breaker can reduce the viscosity of the associative fracturing fluid within 6 hours to less than 5 mPa·S,the breaker residue is less than 92 mg/L,and the surface tension is 26.6 mN·m-1.The corrosion rate of the two liquid breakers on N-80 carbon steel is less than 1 g·m-2·h-1,and the freezing point can be controlled between-5? and27?.The experimental data on the well shows that for 10 experimental wells in Daqing Oilfield,the addition of liquid breaker does not affect the crosslinking and sand carrying performance of the fracturing fluid,and the gel breaking effect is good.The average viscosity of the flowback fluid is 2.81 mPa·S.In view of the high cost of temporary plugging agents used in repeated fracturing of old wells,low pressure-forming ability and poor solubility,temporary plugging agents in fractures and blasthole temporary plugging agents have been designed and developed.Using water-soluble thermoplastic resin as the main material of the temporary plugging agent,an extruder and an injection molding machine were used to prepare the temporary plugging agent in the seam and the temporary plugging agent for blastholes at 40-80?.Among them,the plugging pressure of the temporary plugging agent in the seam Above 40 MPa,the pressure-bearing time exceeds 2 h;the pressure-bearing capacity of the blasthole temporary plugging agent is more than 60 MPa,and the pressurebearing time exceeds 2 h.The dissolution rate of temporary plugging agent in fractures exceeds 99%,the blocking rate is>99%,and the dissolution rate of temporary plugging agent for blastholes exceeds 95%.