海水基耐温聚丙烯酰胺压裂液的性能优化

Performance Optimization of High Temperature Resistant Sea Water Based PAM Fracturing Fluid

以丙烯酰胺、丙烯酸和2-丙烯酰胺-2-甲基丙磺酸(AMPS)三元共聚物(PSAM)为稠化剂,乳酸锆为交联剂开发出一种海水基耐高温压裂液,考察了PSAM的水解度、相对分子质量、AMPS含量、稠化剂和交联剂的浓度、配比等因素对冻胶形成及耐温耐剪切性能的影响,通过测试不同条件下冻胶的储能模量(G')随时间的变化,研究了Ca^(2+)浓度和AMPS含量对交联动力学的影响。交联动力学的研究表明,随AMPS含量加大,PSAM交联速度降低,达到交联平衡所需时间延长,随Ca^(2+)浓度增高,交联反应速度越快,冻胶初始强度越高;耐温性能测试表明,当稠化剂中羧酸基含量与交联剂中锆离子含量之比n(—COOH)/n(Zr^(4+))≈1时,体系的耐温耐剪切性能最优,高含量AMPS提升压裂液的耐温耐剪切性能。在优化稠化剂结构条件下,稠化剂质量分数为0.6%、交联剂质量分数为0.3%配制的海水基压裂液,在150℃、170 s^(-1)下剪切120 min后,黏度保持在150 m Pa·s以上,耐温耐剪切性能优秀。

A high temperature resistant sea water based fracturing fluid with a kind of acrylamide, acrylic acid and 2-acrylamide-2-methylpropane sulfonic acid （AMPS） terpolymer as thickening agent and zirconium lactate as crosslinking agent was prepared. The effects of PSAM 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. The influences of Ca2＋ concentration and AMPS content on crosslinking dynamics were studied by investigating the variation of gel storage modulus （G＇） over time at different conditions. The results show 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 1[n（-COOH）/n（Zr4＋）=1]. Viscosity was maintained at over 150 mPa·s after the crosslinked polymer gel was sheared at 170 s-1 for 120 min at 150℃; The study of crosslinking dynamics show that the crosslinking rate accelerates and the strength of the gel strengthens with the Ca2＋ concentration increases. It takes longer time for the crosslinking reaction reaches an equilibrium when the PSAM sample contains high AMPS content.