新型Gemini表面活性剂复合清洁压裂液体系

为构建新型低伤害复合清洁压裂液体系，在合成阳离子双子表面活性剂的基础上，通过复配非离子表面活性剂以及有机盐助剂，研制出一种新型Gemini表面活性剂复合清洁压裂液体系。室内对压裂液体系进行了性能评价，结果表明120 ℃、170 s-1条件下剪切90 min后体系黏度仍可维持在90 mPa·s左右，具有良好的耐温抗剪切性能；体系在较低的黏度下仍具有较高的弹性，可以满足携砂要求；体系在室温下放置90 d后黏度几乎没有变化，具有良好的稳定性；使用煤油和地层水破胶20 min后的体系黏度均小于5.0 mPa·s，说明体系破胶迅速彻底；破胶液的界面张力分别为0.416 mN/m和0.605 mN/m，有利于压裂破胶液的返排；使用煤油和地层水破胶后的破胶液对天然岩心的伤害率分别为8.71%和12.02%，具有低伤害的特点。现场应用结果分析表明，使用新型Gemini表面活性剂复合清洁压裂液体系的CZ-22井压裂后的日产油量为未压裂邻井CZ-21井的4倍多，压裂增产效果显著。

A new compounded clean fracturing system based on Gemini surfactant

This paper is aimed at building up a new compounded clean fracturing system of low damage. After cationic Gemini surfactant was synthesized, a new compounded clean fracturing system based on Gemini surfactant was developed by combining nonionic surfactant with organic salt additive. Then, its performance was evaluated in laboratory. It is shown that after this fracturing system is sheared at 170 s-1 under 120 ℃ for 90 min, it is better in temperature and shear resistance and its viscosity is still kept at about 90 mPa·s. Its elasticity is still higher in the case of lower viscosity, so it can satisfy the demand of proppant carrying. After this fracturing system is set under the air temperature for 90 d, its viscosity is nearly constant, indicating good stability. Its viscosity is lower than 5.0 mPa·s after gel breaking for 20 min by kerosene and formation water. And it is indicated that the gel breaking of this fracturing system is fast and thorough. The interfacial tension of gel breakers is 0.416 mN/m and 0.605 mN/m, respectively, which are favorable for the back flow of fracturing gel breaker. After gel breaking by kerosene and formation water, their damage ratios to natural cores are 8.71%and 12.02%, respectively, presenting the characteristic of low damage. This new type of compounded clean fracturing system based on Gemini surfactant is applied on site in Well CZ-22. It is shown that after the fracturing, the daily oil production of Well CZ-22 is four times that of its neighboring unfractured well (Well CZ-21). It is demonstrated that the fracturing stimulation effect of this fracturing fluid system is remarkable.