Synthesis And Properties Of Seawater-based High Temperature Tolerant PAM Fracturing Fluid

In order to carry out the high temperature fracturing operation for offshore oil extracting,two kinds of organic zirconium were synthetized separately with zirconium oxychloride and zirconium acetate as main material,lactic acid,triethanolamine and glycerol as ligands.A type of organic aluminum was synthetized with alchlor and acetic acid.Different kinds of PAM thickening agent which can dissolve quickly in seawater was prepared in order to form crosslinked gel fracturing fluid.Impact of The effects of PSAMD structure?molecular weight,degree of hydrolysis,AMPS content?,reactants concentration and blending ratio on gel formation,the temperature resistance and shear resistance performance were investigated,main conclusions were obtained as flows:?1?The formula of organic zirconium crosslinking agent is optimized through laboratory experiment.The effect of mass ratio of oxychloride and triethanolamine,degree of hydrolysis,molecular weight on crosslinking performance,temperature resistance and shear resistance performance were investigated.When the mass fraction of thickening agent is 0.6% and crosslinking agent is 0.3%,viscosity of the gel maintaines at over 130 mPa·s after the crosslinked polymer gel was sheared at 170 s^-1 for 120 min at 120?,it meets the requirements of service under wells bottom hole temperature at 120?.?2?The results of aluminium acetate crosslinking system research shows that: with increase of crosslinking agent ranges from 0.5% to 1.0%,both early viscosity and reservations viscosity increase first and then decrease by the mass fraction of thickening agent remains at 0.6%.The polymer gel reach the optimal temperature resistance and shear resistance performance when adding quantity of crosslinking agent is 0.8%.Viscosity of the gel maintaines at 105 mPa·s after the crosslinked polymer gel was sheared at 170 s^-1 for 90 min at 90?.?3?The results of zirconium lactate crosslinking system research shows that: the polymer gel reach the optimal temperature resistance and shear resistance performance when the ratio of carboxylic group in thickening agent to Zirconium in crosslinking agent equals to 1?n?-COOH?/ n?Zr+4?= 1?.Too much or too little of crosslinking agent can cause the decrease of both early viscosity and reservations viscosity.The amount of divalent cation has an important effect on the crosslinking process.It cannot form effective gel without enough divalent cation.The crosslinking rate and polymer gel strength increase with increasing amount of calcium.The crosslinking rate and polymer gel strength decrease while the temperature resistance and shear resistance performance increase with decreasing amount of AMPS.Viscosity maintains at 90 mPa·s and 130 mPa·s after the crosslinked polymer PSAMD0-1.5-772 and PSAMD0-1.5-822 gel was sheared at 170 s^-1 for 120 min at 120 ?.Viscosity maintains at over 150 mPa·s after the crosslinked polymer PSAMD40-1.5-960 gel was sheared at 170 s^-1 for 120 min at 150?,which has good temperature resistance and shear resistance.The pilot and production process of PSAMD40-1.5-960 were obtained.A high temperature resistant seawater-based fracturing fluid with pilot polymer powder as thickening agent,zirconium lactate as crosslinking agent with clay stabilizer,clean up,additive and gel breaker was prepared.Comprehensive performance of the fracturing fluid was measured refering to Recommended practices on measuring the properties of general technical specifications of fracturing fluid SY/T 6376-2008.The results shows that: the fracturing fluid have good temperature resistance and shear resistance,prefect sang suspending performance,small filter loss,less broken glue residue,damage to the core matrix less then industry standards.It meets the 150? condition required hydraulic fracturing operation.