一种新型乳化胶凝酸的制备与性能评价

摘要

Gelled acids have commonly been used as retarded acids in acid fracturing carbonate reservoirs. Gelled acids have good retarding and friction reducing performance, they cannot satisfy the requirements of deep acidification of high temperature reservoirs though, and a retarded acid with high temperature resistance and better retarding performance is required. Emulsified acids have these characteristics such as low filter loss, good retarding performance, and capable of generating long acid-eroded fractures, it is the poor high temperature stability of emulsified acids limits their application in acid fracturing operations. In this study, a gel acid and an emulsified acid were mixed together in the development of a new retarded acid, the so-called emulsified gelled acid (EGA). The formula and preparation method of an EGA resistant to 120 ℃ were determined through laboratory experiment. The stability, temperature resistance, high temperature rheology and acid-rock reaction have been evaluated. It showed that the EGA prepared was stable at room temperature, no segregation and demulsification have ever been observed after standing 48 hours. The EGA can maintain stable for 2 hours under 120 ℃. The viscosity of the EGA after sheared 80 min under 120 ℃ and 170 s-1 was 40 mPa·s. Kinetics of the reaction between the EGA and rocks indicated that the reaction rate of EGA with rocks was less than that of emulsified acid and gelled acid with rocks, respectively. These data demonstrate that EGA has good high temperature resistance, double retarding performance, and is worth popularizing.%在碳酸盐岩储层酸压施工中,胶凝酸作为常用缓速酸体系,具有良好缓速效果和降摩阻效果,但不能满足高温储层深度酸化要求.因此,需要研发耐温和缓速性能更加优良的缓速酸液体.乳化酸具有滤失量小、缓速性能好、能产生较长酸蚀裂缝的特点,其高温稳定性差限制了进一步推广应用.本研究将胶凝酸和乳化酸合二为一,研发了一种新型双重缓速酸液体系——乳化胶凝酸(EGA).室内实验确定了耐温120℃乳化胶凝酸配方与制备工艺,并对乳化胶凝酸体系的稳定性能、耐温性能、高温流变性能、酸岩反应等进行了评价研究.乳化胶凝酸室温下稳定放置48 h无分层破乳现象,120℃下可稳定2 h以上,120℃、170 s-1下剪切80 min后黏度大于40 mPa·s,酸岩反应动力学实验表明乳化胶凝酸酸岩反应速率小于乳化酸及胶凝酸.说明乳化胶凝酸体系具有良好的耐温性能、耐温耐剪切性能、双重缓速性能,具有良好的推广应用前景.