Research On High Strength Composite Gel System And Its Sealing Performance

In this paper, in view of the current domestic and foreign selective water plugging’problems, such as short effective time, low water plugging efficiency and the non objectivelayer pollution by blocked agent, studied high strength composite gel system’ formulation andits sealing performance using the combination of temporary plugging agent, resol resinprepolymer and visco elastic polymer gel system.A new type of composite temporary plugging agent was developeded with guanidine gum,inorganic filler, particle as raw material, and investigated the related factors that influenced theperformance of composite temporary plugging agent, and through the core flow experimenttested the sealing performance of the temporary plugging agent. Experimental results showedthat when the guar gum solution mass fraction is0.8%, the amount is65%, crosslinking ratiowas100:0.2, the amount of body particles was0.6%, the amount of inert filler was30%, thecomposite temporary plugging agent had a good initial liquidity and strong compressivestrength after formating plugging slug, and gel breaking thoroughly, and can be easily brokendown, and the biggest breakthrough pressure of simulation experiment can reach25.91MPa.Resol resin prepolymer system was developed with phenol, formaldehyde and sodiumhydroxide as the raw material using two step alkali catalyzed method, studied the relatedfactors that influenced the properties of resol, determined the suitable reaction conditions,observed the influences of curing agent dosage and types, and curing temperature on resolresin curing properties, tested the plugging performance of resol prepolymer as blocking agent.The experimental results showed that resol resin prepolymer solution with moderate viscositycan be obtained when the molar ratio of phenol and formaldehyde was1:3, then added80%formaldehyde of the required amount, heated up to60℃, and reacted50min; the second stepadded1.5%catalyst, heated up to70℃, then added the20%formaldehyde of the requiredamount, heated up to90℃, and reacted30min. ammonium chloride is an ideal curing agentfor resol resin prepolymer, the curing time can be adjusted according to curing agent dosage,and gravel pores can be well plugged with high plugging strength.The viscoelastic polymer gel plugging system was developed using acrylamide, sodiummethacrylate, methylene bisacrylamide as raw material, tested related factors that influencedthe performance of viscoelastic polymer gel, determined the reaction conditions of viscoelasticpolymer gel system, then tested water swellable properties and plugging performance as water plugging agent. The experimental results show that when the acrylamide was6%~8%, sodiummethacrylate was2%, ammonium persulfate as0.15%~0.20%, rate controlling agent as0.04%~0.06%, methylene bisacrylamide is0.2%, pH value is neutral, the reaction temperatureis60~80℃, viscoelastic gel was formed with high strength, reaction time and gel strength canbe adjusted in a certain range, viscoelastic polymer gel has good water swellable performancein the brine water, good stability, and strong sealing performance.Simulation experiments results showed that high strength sealing plug could be formedusing the combination of temporary plugging agent, resol resin prepolymer and visco elasticpolymer gel system, the highest plugging breakthrough pressure gradient could reach up to28.82MPa·m-1showing good plugging performance.