临南油田弱碱性水表面活性剂驱油体系研究

Development of Alkaline Water and Surfactant Composite Flooding Systems in Linnan Oilfield

为适应临南油田注弱碱性水开发需要,研发弱碱性水条件下的驱油表面活性剂对于油田增产增注具有重要意义。临南油田采出水为中性水,p H值6.89,矿化度44118 mg/L;处理水为弱碱性水,p H值7.88,矿化度39116 mg/L。通过测试不同类型表面活性剂与原油间的界面张力,优选出脂肪醇醚磺酸盐和烷醇酰胺类非离子表面活性剂构成的复合体系CDS6,探讨了溶液介质对界面张力的影响,优化了注入段塞和注入浓度。优化的复合体系CDS6组成为:0.1%CEOS6+0.2%CDA01。以中性水和弱碱性水作为介质时,CDS6体系与原油间的界面张力分别为5.84×10-3和1.70×10-3m N/m,弱碱性水与CDS6复配具有较好的降低界面张力的协同作用。物模驱油实验结果表明,弱碱性水配制的CDS6驱油效率高于中性水。在注入量0.4 PV时,0.3%CDS6弱碱性水溶液的驱油效率为57.33%,比水驱提高10.66%。

Due to the EOR need of injecting weak alkaline water in Linnan oilfield,developing surfactant system under the condition of weak alkaline water was of great significance. The production water in Linnan oilfield was neutral water with p H value of 6.89 and salinity of 44118 mg/L,while the treated water belonged to weak alkaline water with p H value of 7.88 and salinity of39116 mg/L. By testing the interfacial tension between different types of surfactants and crude oil,the compound system CDS6 composed of fatty alcohol ether sulfonate(CEOS6) and amide-type nonionic surfactant(CDA01) was selected. The effect of solution medium on interfacial tension and the optimized slug injection and concentration of surfactant were also investigated. The experiment results showed that the constituent of optimum compound system CDS6 was obtained as follows: 0.1% CEOS6+0.2%CDA01. The interfacial tension of composite surfactant system in neutral water and weak alkaline water with crude oil was 5.84×10-3and 1.70×10-3m N/m,respectively. Weak alkaline water had synergistic effect with CDS6 in decreasing interfacial tension. The simulation flooding test results showed that the oil displacement efficiency of 0.3% CDS6 in weak alkaline water was higher than that in neutral water. The oil displacement efficiency of 0.3% CDS6 weak alkaline solution at the slug injection of 0.4 PV was57.33% which was improved by 10.66% compared with that of water flooding.