硫离子与部分水解聚丙烯酰胺溶液性能的研究

Research on performance of sulfur ions interacting with partially hydrolyzed polyacrylamide solution

渤海某油田在注水等作业过程中造成了不同程度的SRB污染,加之注入水中含有大量的硫酸盐,导致了H_(2)S的不断生成,同时油田含水上升快,常规的聚驱流度控制技术受到了挑战。为探讨S2-对聚合物溶液性能的影响,对HPAM粘均分子量、流变性能、各亲水基团中心原子水化能力等进行了研究,利用分子动力学研究了Na_(2)CO_(3)抑制S^(2-)降粘机理。结果表明,16 mg/L H_(2)S对浓度为2500 mg/L的HPAM的降粘率约76%;随着S^(2-)浓度增加,稠度系数K降低,幂律因子n增大,溶液增粘效果变差,其原因是由于S^(2-)使得分子主链断链、侧基基团发生卷曲收缩;在H_(2)S存在条件下,Na_(2)CO_(3)与HPAM形成“竞争”性反应,Na_(2)CO_(3)优先与S^(2-)反应,从而降低S^(2-)含量,达到了抑制S^(2-)降粘作用的目的,也为含H_(2)S油藏聚驱有效控制流度提供了思路。

In the process of water injection and other operations in a Bohai oilfield,SRB pollution of different degrees was caused.In addition,the injected water contains a lot of sulfate,which leaded to the continuous generation of H_(2)S.At the same time,the water cut of the oilfield rises rapidly,so the conventional polymer flooding mobility control technology was challenged.In order to investigate the effect of S^(2-) on the properties of polymer solution,the viscosity average molecular weight,rheological properties and the hydration ability of each hydrophilic group central atom of HPAM were studied.The mechanism of inhibition of S^(2-) by Na_(2)CO_(3) was studied by molecular dynamics.The results showed that the viscosity reduction rate of 2500 mg/L HPAM by 16 mg/L H_(2)S was about 76%;with the increase of S^(2-) concentration,the consistency coefficient K decreases,the power-law factor n increases,and the viscosity increasing effect of the solution becomes worse.The reason is that S^(2-) makes the main chain broken and the side group curl and shrink;in the presence of H_(2)S,Na_(2)CO_(3) and HPAM form a“competitive”reaction,and Na_(2)CO_(3) preferentially reacts with S^(2-),so as to reduce the content of S and reach the maximum viscosity.The purpose of inhibiting the viscosity reduction of S^(2-) is to provide an idea for the effective control of mobility in the polymer flooding of the reservoir containing H_(2)S.