国家青年科学基金“稠油火烧油层过程中二次点火热化学反应微观机理研究”（52004259）；南海西部油田上产2000万方关键技术研究（编号：CNOOC-KJ 135 ZDXM 38 ZJ 01 ZJ）。
China University of GeosciencesWuhan Wuhan Hubei
针对低渗油藏作业、洗井过程中,储层流体返吐至井筒导致启注压力升高的难题,通过室内实验优选出了一种快速就地形成的中相微乳液,体系组成为：1%~8%非离子/阴离子表面活性剂体系、1.5%-3.5% C5醇和3.5% KCl水溶液。考察了中相微乳液体系的形成时间、增溶油量、界面张力、洗油能力和“鱼状”相图特征。结果表明,该体系形成的中相微乳液体系就地形成并稳定时间为10~30 min,界面张力达到10-2~10-3 mN/m,洗油率达到98%~99%。基于目标储层地质参数、注水参数和“鱼状”相图特征,设计了就地生成中相微乳液的注入参数,初始注入浓度为7.01%表面活性剂+3.33%C5醇+ 3.5% KCl 溶液,注入量为14.35 m3,然后转注C5醇浓度为1.2%的水溶液86.25 m3,可使半径为3.0m的储层均得到中相微乳液的清洗,达到降压增注的目的。
In view of the difficulty in raising the injection pressure caused by the reservoir fluid flowing back to the wellbore during the operation and well washing operations in low permeability reservoirs, a fast in-situ microemulsion was developed through laboratory experiments. The system consisted of 1%~8% non-ionic / anionic surfactant system, 1.5%-3.5% C5 alcohol and 3.5% KCl aqueous solution. The formation time, oil content, interfacial tension, oil washing ability and fishlike phase diagram of the microemulsion system were investigated. The results showed that the microemulsion system was formed in situ and stabilized for 10 ~ 30 min, the interfacial tension reached 10-2 ~ 10-3 Mn / m, and the oil washing rate reached 98% ~ 99%. Based on the geological parameters, water injection parameters and fishlike phase diagram characteristics of the target reservoir, the injection parameters of in-situ microemulsion are designed. The initial injection concentration is 7.01% surfactant +3.33%C5 alcohol + 3.5% KCl solution, the injection volume is 14.35 m3, and then the water solution 86.25 m3 of C5 alcohol concentration is 1.2%. The reservoir with 3.0m radius could be cleaned by the middle phase microemulsion to achieve the purpose of reducing pressure and increasing injection.