低温活化过硫酸盐降解聚合物冻胶

Low Temperature Degradation of HPAM Gel by Activation of Persulfate

温度是影响聚合物冻胶降解的关键因素。针对低温油藏中聚合物冻胶引起的堵塞,提出使用过硫酸盐为氧化降解剂,通过低温活化的方法提高过硫酸盐的氧化性。首先,以水合硫酸铜和亚氨基二琥珀酸四钠等为原料制得活化剂(TA);然后,利用自由基淬灭实验和自由基测试,分析TA活化过硫酸盐降解聚合物的机理;最后,研究了不同温度下活化体系中过硫酸盐浓度和TA浓度等对降解聚合物冻胶的影响,优化了活化体系的配方,并评价了该体系的腐蚀性。结果表明,35℃时,TA活化过硫酸盐体系能快速降解聚合物冻胶,形成的超氧阴离子自由基是降解冻胶的主要活性自由基。随着过硫酸盐浓度的增加,降解率增大,但TA的浓度存在最佳值,而温度升高可以加快冻胶降解。和常规解堵剂相比,TA活化过硫酸盐能快速降解聚合物冻胶,且腐蚀性小。低温下,由0.10 mol/L过硫酸钠和0.12 mol/L TA组成的体系的降解效果好于其他常规聚合物驱油藏解堵剂。

Temperature is a key factor limiting the degradation of polymer gel.Aiming at the blockage caused by polymer gel in low temperature reservoirs,the oxidation ability of persulfate was improved by low temperature activation using persulfate as oxidation reducer.First,the activator(TA)was prepared from copper sulfate hydrate and tetrasodium iminosuccinate.Then the quenching experiment and the radical test were used to analyze the degradation mechanism of the polymer gel.Finally,the effect of persulfate concentration and TA concentration on the degradation of polymer gel at different temperature was studied.The formula of activation system was optimized.Meanwhile,the corrosivity of the system was also evaluated.The results showed that TA activated persulfate could rapidly degrade the polymer gel at 35℃.The superoxide anion radicals were the main active radicals in degradation reaction.With the increase of persulfate concentration,the degradation rate increased,but the concentration of TA had the optimal value,and the temperature increase could accelerate the degradation of gel.Compared with other polymer plugging removers,TA activated persulfate could rapidly degrade polymer gel with mild corrosion.At low temperature,the system composed of 0.10 mol/L sodium persulfate and 0.12 mol/L TA had better degradation effect than other conventional polymer flooding reservoir plugging agents.