用EQCM研究油田采出水中聚合物对碳酸钙垢生长的影响规律

Influence of Polymer on the Scaling of Calcium Carbonate in Produced Water Using EQCM

刘宗昭 郭海军 王 虎

LIU Zong-Zhao GUO Hai-Jun WANG Hu

油田注聚产出液中，由于残余聚合物具有螯合钙离子的能力，常规化学方法难以准确而快速地评定其结垢趋势。采用电化学石英晶体微天平（EQCM）技术可以准确而快速地对含聚合物采出水进行碳酸钙加速结垢评价。研究表明，极化电位、温度和钙离子浓度对结垢影响较大。电位阴极极化程度越大、温度越高、钙离子浓度越大，结垢趋势越明显，结垢速率越快。线性聚丙烯酰胺（HPAM）使金电极表面结垢速率降低，50 mg/L HPAM抑制结垢的效率大于500 mg/L HPAM。极化电位越大，碳酸钙晶体数量越多、尺寸越大、聚集越明显。HPAM对碳酸钙晶体形貌的影响较大。无聚合物时，结垢产物以六面体晶体状为主。在低极化电位下（-0.6 V），碳酸钙垢晶体为片球状和六面体结构；在高极化电位下（-1.4 V），碳酸钙晶体呈现不规则圆形堆积物（50 mg/L HPAM）或花型结构（500 mg/L HPAM）。电场和聚合物在碳酸钙晶体上的吸附作用是造成这些形貌上差异的主要原因。

It was difficult to rapidly and accurately evaluate the scaling tendency of produced water containing polymer for the chelation ability of residual polymer. In this paper, electrochemical quartz crystal microbalance (EQCM) technique was used to evaluate the accelerated calcium carbonate scaling behavior in produced water containing polymer. The results showed that polarized potential, temperature and the concentration of calcium ion had remarkable influence on scaling. More negative polarization of the potential, higher temperature and more concentrated calcium solution were beneficial to scaling tendency and scaling rate. The presence of linear polyacrylamide (HPAM) lowered the scaling rate on the surface of gold electrode. The inhibition effect of 50 mg/L HPAM addition was more apparent than that of 500 mg/L HPAM. The higher polarized potential, the more number of calcium carbonate crystal was with greater size and more obvious aggregation. The presence of HPAM had pronounced effect on the morphology of calcium carbonate crystals. In the absence of HPAM, the shape of scale was mainly hexahedron. In lower polarized potential (-0.6 V), the CaCO3 crystals looked like balls compiled with pieces and regular hexahedron. In higher potential (-1.4 V), it took the shapes of irregular round piles (50 mg/L HPAM) or flower alike structures (500 mg/L HPAM). The main reason for these special morphologies lay in the potential field effect and the adsorption of polymer molecules on the scale crystal.