聚醚改性有机硅表面活性剂构效关系及压裂助排性能

Structure-function relationship of polyether-modified siloxane surfactants and performance in the fracturing fluid as clean-up additives

摘要:

为系统研究有机硅表面活性剂分子结构与表面张力、界面张力、乳化、润湿和耐水解稳定性之间的构效关系，以七甲基三硅氧烷（MDHM）和三种烯丙基聚醚〔甲基烯丙基聚氧乙烯醚（MAPEG）、烯丙基聚氧烷基乙酰基醚（APAE）和烯丙基聚氧烷基环氧基醚（APAEE）〕构筑了三种聚醚改性有机硅表面活性剂MAPEG-MDHM、APAE-MDHM和APAEE-MDHM-ATS，采用响应面法优化了合成的最佳反应条件，评价了三种聚醚改性有机硅表面活性剂的表面张力、界面张力、乳化、润湿和耐水解稳定性，探究三种表面活性剂分子结构与其性能之间的构效关系，发现烯丙基聚醚封端基团的亲疏水性、界面层表活分子堆积体积/横截面积、静电势分布分别是影响表面张力和界面张力、乳化性能和耐水解稳定性、润湿性的主要因素。以耐水解稳定性最好的双子型有机硅表面活性剂APAEE-MDHM-ATS作为压裂用助排剂，考察其与胍胶压裂液的配伍性和破胶后返排性能，结果表明，该助排剂添加质量分数为0.3%时，胍胶压裂液破胶后黏度为2.8 mPa?s，表面张力为22.4 mN/m，助排率为45%。

Abstract:

To understand the structure-function relationship between the molecular structure of organosilicon surfactants and surface tension, interfacial tension, emulsification, wettability and hydrolysis resistance, three polyether-modified organosilicon surfactants were designed and synthesized through combining the heptamethyltrisiloxane with allyl polyethers. The optimum synthesis conditions were determined by the response surface methodology. The surface and interfacial tension, emulsification, wettability and hydrolytic stability were evaluated. Moreover, the structure-function relationship of these organosilicon surfactants was elucidated. It is proposed that the hydrophilicity, molecular volume/cross-sectional area of surfactants stacked at interface, and polarity of the tail end within polyether chain are the main factors affecting the surface/interface tension, emulsification and hydrolytic stability, and wettability, respectively. Finally, APAEE-MDHM-ATS with the best hydrolysis resistance was employed as a clean-up additive in the fracturing fluid to study the compatibility with guanidine fracturing fluid and cleanup performance of drainage. It is found that APAEE-MDHM-ATS of 0.3wt.% shows a good compatibility, associated with a viscosity of 2.8 mPa?s, surface tension of 22.4 mN/m, and a cleanup additive efficiency of 45% after gel breaking.