阳离子双子表面活性剂在三次采油领域的应用基础研究

【作者】 杨建军；

【导师】 罗平亚； 叶仲斌；

【作者基本信息】 西南石油学院 ， 油气田开发工程， 2005， 博士

【摘要】 与普通表面活性剂相比,双子表面活性剂具有很低的cmc值和很高的界面活性,这两大特性是目前三次采油中驱油用的任何一种表面活性剂所无法比拟的。本文就是利用双子表面活性剂的高界面活性这一重大特性,将其引入到三次采油领域,并开展一系列的研究,以期解决目前普通表面活性剂在该领域所面临的难题,同时也为以后双子表面活性剂的现场应用研究提供技术和理论支持。 通过阳离子双子表面活性剂产品的合成与表征,结果表明:红外光谱法证明了室内合成样品分子中季铵盐结构的存在;核磁共振法证实了室内合成样品分子中双子结构的存在;最终证实了室内合成样品为目标产物——阳离子双子表面活性剂。 阳离子双子表面活性剂降低油/水界面张力的规律和机理研究结果表明,该类表面活性剂具有很高的界面活性;在无碱和较低浓度下,可以将油/水界面张力降至10^-3mN/m数量级;油的重质组分含量越高,越利于双子表面活性剂降低油/水界面张力;在降低O/W的IFT过程中,双子表面活性剂本身的分子结构与油的组分之间存在匹配性。为双子表面活性剂用于无碱复合驱提供了可能性,也对于在油田开发过程中,运用阳离子双子表面活性剂降低油/水界面张力提供了新的方向和途径。 运用均匀设计研究了阳离子双子表面活性剂与普通表面活性剂在降低油/水界面张力方面的协同效应。研究结果表明:双子表面活性剂与普通非离子表面活性剂混合后,在降低油/水界面张力方面可以协同增效;均匀设计在研究化学驱、复合化学驱领域具有十分广泛的应用前景。通过本部分的研究工作,为在油田开发过程中,有效利用双子与普通表活剂的协同效应,提高效率和降低成本提供了理论和实践上指导。 阳离子双子表面活性剂对固体表面润湿的影响研究结果表明:对于油湿固体表面,阳离子双子表面活性剂可将亲油表面最终改变为亲水甚至强亲水表面;对于水湿固体表面,多数阳离子双子表面活性剂可将亲水表面最终改变为弱亲水表面。通过本部分的研究,为运用阳离子双子表面活性剂改变油藏岩石润湿性,从而有利于提高驱油效率提供了理论和实践方面的指导。 阳离子双子表面活性剂的微观驱油过程研究结果表明:①在毛管模型中,双子表面活性剂溶液具有比水驱高得多的驱油效率,同时也表明了相同浓度的双子表面活性剂GS12-4溶液的驱油效率好于GS14-2溶液;②在填砂微观模型中,GS12-4溶液比GS14-2溶液具有更高的驱替效率;结合两种微观模型和岩心驱油结果表明,双子表面活性剂具有很高的驱油效率;润湿性对驱油效率具有很大的影响;最后根据实验过程和结果,分析出阳离子双子表面活性剂的驱油机理,主要包括降低油/水界面张力机理、改变岩石表面润湿性机理、聚并形成油带机理以及乳化机理。 综上所述,阳离子双子表面活性剂有望成为三次采油用的高效驱油剂。更多还原

【Abstract】 Compared with conventional surfactants, Gemini surfactants exhibit lower cmc value and higher surface activity, which make them superior to the sole surfactant employed in EOR area at present. Owing to the superiorities Gemini surfactants have mentioned above, which could be introduced into EOR area. In this dissertation, a series of research on Gemini surfactants were carried out, so as to solve the problems conventional surfactants confronted at present, and at the same time, which would provide the technical and theoretical support on the applied research of Gemini surfactants in oil field.The synthesis and characterization results of cationic Gemini surfactants indicated that, first, there exists quaternary ammonium structure in the molecules of sample synthesized in lab by 红外光谱法 method, second, NMR method verified the existence of Gemini structure in the molecules of sample synthesized in lab, last, through the two methods mentioned above, the samples synthesized are sure to be object product, that is, cationic Gemini surfactants.The investigation results of cationic Gemini surfactant solution reducing oil/water interfacial tension indicated that this sort of surfactants have high interfacial activity, and at low concentration and no alkaline added, Gemini surfactants could reduce water and oil interfacial tension even to super-low level, that is 10~-3mN/m order of magnitude, and with the increase of heavy components of oil, Gemini surfactants reduce O/W IFT easier, and the results also indicated that during the course of Geminis reducing O/W IFT , there exists the match between Gemini molecule structure and the components of oil. The results would provide probability on employing Gemini surfactants into compound flooding with no alkaline, which will make it possible to employ Gemini surfactants to reduce oil/water IFT during the course of oil exploitation.The research was carried out on synergetic effect of cationic Gemini surfactants and conventional surfactants mixture reducing oil and water interfacial tension by use of Uniform Design, and the results indicated that there exhibited obvious synergetic effect for non-ion conventional surfactant, OP-10, and Gemini surfactant, GS14-2-14, during the course of mixture reducing oil /water IFT, and Uniform Design method can be used in the area of chemical flooding and compound chemical flooding. And the investigation results in this part can guide for making use of the synergetic effect resulted from Gemini surfactants andconventional surfactants to increase efficiency and decrease cost.The investigation results of cationic Gemini surfactants converting solid surface wettability indicated that cationic Gemini surfactants could convert oil-wet surface into waterwet surface, even into strong water wet surface. And as for water wet surface, most cationic Gemini surfactants could convert water-wet surface into weak water-wet surface. The investigation results in this part would provide the theoretical and practical guide for employing cationic Gemini surfactants to change the wettability of reservoir, so as to enhance oil displacement efficiency.Microscopic displacement course and results of cationic Gemini surfactants’ solution indicated that, in capillary model, Gemini surfactants exhibited higher oil displacement efficiency than water, and at the same concentration, GS12-4 exhibited higher oil displacement efficiency than GS14-2. and in sand packed model, GS12-4 exhibited higher oil displacement efficiency than GS14-2, too. The two microscopic models and core flooding results indicated that Gemini surfactants solution have high oil displacement efficiency and wettability of solid surface also influences oil displacement efficiency a lot. At last, according to the microscopic displacement course and results, oil displacement mechanism of cationic Gemini surfactants was put forward, which includes reducing O/W IFT, converting the wettability of solid surface, conglomerating oil drop, forming oil zone and emulsifying crude oil, and etc.In all, cationic Gemini surfactants can be an effective oil displacement chemical in EOR area.更多还原