低渗透油气藏用防水锁剂体系的制备与性能评价

Preparation and Performance Evaluation of Waterproof Lock Agent System for Low Permeability Oil and Gas Reservoir

为改善低渗透油气藏水锁损害,以多元醇和脂肪酸为主要原料制备非离子型表面活性剂,将其与分散剂和稳定剂混合制得防水锁剂体系。通过红外光谱对表面活性剂的结构进行了表征,研究了防锁水剂体系水溶液的粒径分布,表面张力、热稳定性及对页岩岩心接触角的影响。结果表明,表面活性剂产物的热分解温度为218℃,在清水中的分散达到微-纳米级别。80℃下防锁水剂体系水溶液的表面张力可降至19.68 mN/m,临界胶束浓度为80 mg/L,表现出良好的抗盐性能。页岩岩心在常温常压下浸泡于防水锁剂体系水溶液中4 h后,清水在岩心表面的接触角从46.1°增至80°数130°;防水锁剂体系经过120℃老化8 h后,清水在岩心表面的接触角仍可达103.9°。防锁水剂体系抗高温、抗盐、防水锁性能良好,可用于改善低渗透油气藏水锁损害。

In order to improve the water-locking damage of low permeability oil and gas reservoir,polyol and fatty acid were used as main raw materials to prepare non-ionic surfactant.The surfactant product was mixed with dispersant and stabilizer to prepare a waterproof lock agent system.The structure of the surfactant was characterized by infrared spectroscopy,and the particle size distribution,surface tension,thermal stability of waterproof lock agent system and the effect on contact angle of shale core were studied.The results showed that the thermal decomposition temperature of the surfactant was 218℃,and the dispersion in water reached micro-nano level.At 80℃,the surface tension of the waterproof lock agent system solution was reduced to 19.68 mN/m,and the critical micelle concentration was 80 mg/L,indicating good salt resistance.After shale cores were immersed in an aqueous solution of waterproof lock agent system for 4 hours at normal temperature and pressure,the contact angle of clean water on the core surface increased from 46.1°to 80°—130°.After the waterproof lock agent system was aged at 120℃for 8 hours,the contact angle of water on the core surface could still reach 103.9°.The waterproof lock agent system had good high temperature resistance,salt resistance and waterproof lock performance,and could be used to improve the water lock damage of low permeability oil and gas reservoir.