脂肪醇聚氧乙烯醚硫酸钠/疏水缔合聚丙烯酰胺复合体系提高稠油采收率机理

Mechanism of Enhanced Heavy Oil Recovery of Sodium Fatty Alcohol Polyoxyethylene Ether Sulfate/Hydrophobically Associating Polyacrylamide Composite System

通过室内物理模型驱油实验研究了阴-非离子型表面活性剂脂肪醇聚氧乙烯醚硫酸钠(AES)/疏水缔合聚丙烯酰胺(APP5)复合体系的稠油采收率,并与AES/部分水解聚丙烯酰胺(SNF)复合体系进行了比较。结果表明:在1.2 g/LSNF、1.2 g/LAPP5、2.0 g/LAES、50℃条件下,模拟地层水、SNF、APP5、SNF/AES和APP5/AES的最终采收率分别为50.1%、60.0%、61.2%、64.9%和70.7%,APP5/AES复合体系的稠油采收率最大。AES体系与所用稠油不能产生超低界面张力,加入0.1 g/LAPP5或SNF后,APP5/AES、SNF/AES复合体系的最低界面张力也未能得到改善,分别为1.40 mN/m和1.43 mN/m。AES加量为2.0 g/L时,复合体系的黏度高于单一聚合物体系,APP5/AES复合体系黏度最大。在50℃、7.34 s-1下,1.6 g/LAPP5/2.0 g/LAES的黏度为32.42 mPa·s。通过界面张力和黏度测定分析发现:与范德华相互作用相比,分子间疏水作用对增强APP5/AES复合体系的黏度贡献更大。APP5/AES复合体系提高稠油采收率主要是通过提高体相黏度,降低油水流度比,而非降低油水界面张力。

The efficiency of enhanced heavy oil recovery by applying sodium fatty alcohol polyoxyethylene ether sulfate(AES)and hydrophobically associating polyacrylamide(APP5)composite system was investigated using physical model displacement test.The results were compared with that of AES/partially hydrolyzed polyacrylamide(SNF)system. It was found that,under the condition of 1.2 g/L SNF,1.2 g/L APP5,2.0 g/L AES and 50℃,the final recovery efficiency of simulated formation water,SNF,APP5,SNF/AES and APP5/AES was 50.1%,60.0%,61.2%,64.9% and 70.7%,respectively. The heavy oil recovery efficiency of APP5/AES was the highest. The ultra-low interfacial tension could not be obtained when AES system mixed with heavy oil. The lowest interfacial tension of APP5/AES and SNF/AES was not improved after adding 0.1 g/L APP5 and SNF with 1.40 and 1.43 mN/m,respectively. The viscosity of composite system was higher than that of single polymer system with AES dosage of 2.0 g/L,and the viscosity of APP5/AES was the highest. At 50℃ and 7.34 s-1,the viscosity of 1.6 g/LAPP5 and 2.0 g/LAES composite system was 32.42 mPa·s. The mechanism of enhanced heavy oil recovery was analyzed in terms of interfacial tension and viscosity.Compared with the Van der Waals interaction,the hydrophobic effect played a more important role in enhancing the viscosity of APP5/AES system. APP5/AES enhanced oil recovery mainly by increasing the viscosity of composite system and reducing oil-water mobility ratio,rather than reducing the interfacial tension.