大庆油田抗盐聚合物驱矿场试验

Field test of the salt⁃resistant polymer in Daqing Oilfield

在大庆油田现有条件下,采用清配污稀聚合物溶液驱油与采用清配清稀聚合物溶液驱油相比,前者不仅导致聚合物用量增加,而且致使聚合物驱驱油技术效果变差,经济效益下滑。因此,在清配污稀聚合物驱区块大幅度增加的情况下,研究如何降低聚合物用量,改善聚合物驱技术效果,提高经济效益显得尤为重要。对比评价了相同相对分子质量的LH2500抗盐聚合物和常规聚合物(部分水解聚丙烯酰胺)的应用性能。结果表明,LH2500聚合物具有较好的抗盐性、耐热稳定性、黏弹性和注入能力。天然岩心驱油实验表明,清配污稀LH2500聚合物驱比常规聚合物驱多提高采收率4.9百分点,同时降低聚合物质量浓度100 mg/L。在实验室研究的基础上,开展了清配污稀LH2500抗盐聚合物驱现场试验,并与相邻对比区清配清稀常规聚合物驱的开发效果进行了对比,两者沉积环境相同,油层发育特征相似,剩余油饱和度和投产初期综合含水率相近。截止到2020年11月,试验区抗盐聚合物驱阶段提高采收率18.6百分点,比对比区常规聚合物驱多提高采收率3.7百分点。

Under the existing conditions of Daqing Oilfield,compared with the clean water⁃prepared polymer solu⁃tion diluted with clean water,the clean water⁃prepared polymer solution diluted with wastewater will not only con⁃sume more polymer powder,but also reduce the technical effects and economic benefits of the polymer flooding.Therefore,in the case of a large increase in the clean water⁃prepared and wastewater⁃diluted polymer flooding blocks,it is of urgent importance to study how to reduce the polymer consumption,improve the technical effects and enhance the economic efficiency.The applied performances were evaluated for both salt⁃resistant Polymer LH2500 and conventional polymer(partially hydrolyzed polyacrylamide)with the same relative molecular weight.The results indicate that Polymer LH2500 has much better advantages in salt⁃resistant ability,thermal stability,vis⁃coelasticity and injectivity.The oil⁃displacing experiment with natural cores shows that the enhanced recovery factor is 4.9 percentage points higher and the polymer mass concentration is reduced by 100 mg/L for the clean water⁃pre⁃pared polymer flooding diluted with wastewater compared with the conventional polymer flooding.On the basis of the laboratory research,the field test of clean water⁃prepared and wastewater⁃diluted salt⁃resistant Polymer LH2500 flooding was conducted,whose flooded effects were compared with those of the clean water⁃prepared/diluted con⁃ventional polymer in nearby comparison area.The two areas have the same sedimentary environments and similar reservoir developed characteristics,remained oil saturation along with composite water cut at the initial production stage.Up to November 2020,the staged EOR by salt⁃resistant polymer flooding in the test block has reached 18.6 percent points,3.7 percentage points higher than that of the conventional polymer flooding in the comparison block.