一种压裂用黏弹性表面活性剂的合成及其应用性能研究

为降低压裂过程对地层的伤害,以芥酸为主要原料,合成了一种可生物降解的甜菜碱型黏弹性表面活性剂,并对其反应条件进行了优化。最佳合成工艺如下:酰胺化反应中芥酸与N,N-二甲基-1,3-丙二胺的摩尔比为1∶1.2,反应温度150℃,反应时间为12h;季铵化反应中环氧氯丙烷与Na2SO3以等摩尔量混合后与中间体反应,摩尔比为1.2∶1,反应温度80℃,反应时间为6h。最终产物为表面活性剂有效含量为65%的黏稠状物质。同时,利用红外光谱和1 H NMR对提纯后的表面活性剂结构进行表征。对黏弹性表面活性剂压裂液进行应用性能测试,结果表明,该体系在剪切速率170s1,温度高于80℃时,黏度仍大于25mPa.s,60℃剪切3600s后黏度仍大于85mPa.s,说明该体系具有良好的耐温抗剪切性和增稠性能。

SYNTHESIS AND PERFORMANCE OF VES SURFACTANT FRACTURING FLUID

In order to reduce the formation damage of fracturing process,a kind of biodegradable,viscoelastic surfactant,betaine has been synthesized with erucic acid as the main raw material.The synthesis processes have been optimized,and the best conditions are obtained as follows: the first step is amidation,the molar ratio of erucic acid to N,N′-dimethyl-1,3-propane diamine is 1∶1.2,temperature of reaction is 150 ℃,and time of reaction is 12 h;the second step is quaternary ammoniation,epichlorohydrin and Na2SO3 was mixed in equimolar,then reacted with intermediate,the molar ratio is 1.2∶1,temperature of reaction is 80 ℃ and the time of reaction is 6 h.The effective content of the target product was 65%.At the same time,the surfactant structure has been characterized by infrared spectroscopy and 1H NMR.The application performance of the viscoelastic surfactant have been tested,and results show that at the shear rate of 170 s-1,temperature is above 80 ℃,viscosity is larger than 25 mPa·s;after 3 600 s sustained shearing at 60 ℃,the viscosity is still greater than 85 mPa·s.These data indicate that the fluid system have favorable temperature tolerance and shearing resistance performance,and have a good thickening effect.