Research On Clean Acid Fracturing Fluid System

At present,hydraulic fracturing is an important measure for increasing the output of oil-gas field and augmenting injection of water-injection well.The extent of the second damage on reservoir of fracturing fluid relates to the success or failure of fracturing construction.According to the conventional water-based polymer fracturing fluid system easily causes the second damage to reservoir,the purpose of this study was to research a novel acid fracturing fluid system,and its performance inherits the conventional water-based polymer fracturing fluid system,meanwhile it can achieve the low formation damage or no damage.In this paper,researched and synthesized the important parts of water-based fracturing fluid such as thickener and cross-linking agent.Optimized the reaction conditions and performance evaluation.The result show that the acid fracturing fluid system has good shearing,gel breaking,easily return discharge of stratum and low damage.Firstly,using inorganic zirconium salt as raw materials,prepared a low damage,temperature resistant and delayed cross-linking acid cross-linker for acid hydro-fracturing fluids.The optimum reaction conditions were derived as follows:the ratio between m(oxychloride-zirconium),m(H2O)and m(isopropyl)was 1:1.25:5,the ratio between m(hydroxyl acid sodium salt B),m(oxychloride-zirconium)and m(polyalcohol A)was 1:16:20,the reaction temperature was 50?55?,the pH value of solution was2.0,and the reaction time was 4h.Secondly using LA,AM and AMPS as raw materials,prepared a low damage and temperature resistant thickener(MA-3)acid hydro-fracturing fluids.The optimum reaction conditions were derived as follows:the ratio between m(organic acid),and m(acrylamide)was 0.08:1,m(AMPS)was 20%,the reaction temperature was 30?,and the reaction time was 4h.Finally,researched the acid fracturing fluid system performance evaluation.The test results indicated that,the fracturing fluid formed by cross-linker(LY-2)and hydroxypropyl guar gum has been a fine nature,the viscosity of Gel over 150mPa·s,in 4p?,after 170-1shear rate for 120 min,and adding 2%breaker(mass fraction of 15%ammonium per-sulfate)1h after,the viscosity of Gel will down to 1.56mPa-s.the fracturing fluid formed by thickener(MA-3)and aluminum sulfate has been a fine nature,the viscosity of Gel over200mPa s,in 40?,after 170-1 shear rate for 120 min,and adding 1%breaker(mass fraction of15%ammonium per-sulfate)3h after,the viscosity of Gel will down to 3.12mPa·s.The two acid fracturing fluid system performance are better than conventional water-based fracturing fluid system.