不同酸液体系残酸-原油乳状液破乳室内评价

 酸压后的残酸与原油混合形成的乳状液会增加泵、管柱的载荷，也容易造成管柱腐蚀结蜡等，给实际生产带来诸多不便。因此，在酸压后的开井试产前尽量让残酸与原油混合形成的乳状液破乳，将水分脱出。为测定残酸与原油混合形成的乳状液的破乳效果，确定破乳时间，针对目前使用比较广泛的胶凝酸、冻胶酸、变黏酸体系，进行这3 种酸液体系不同浓度残酸与原油混合形成的乳状液的破乳室内评价研究，对各种影响因素进行分析，得出了破乳效果胶凝酸>冻胶酸>变黏酸，在模拟井底温度（90℃）时，胶凝酸残酸原油乳状液破乳脱水率达到98%以上；酸液浓度越低，越有利于破乳，变黏酸的这项特性尤为突出；时间越长破乳效果越好，但在90 min 时达到基本破乳；在高温条件下残酸与原油形成的乳状液破乳快，脱水率高。但随着开井试采，地层原油由储层流动到井口，温度降低，脱水率可能降低。

Demulsification Experiment Evaluation of Emulsion of Crude Oil and Different Spent Acids

The emulsion of crude oil and spent acid after acid fracturing treatment brings many troubles to production, such as increasing the loads of pump and pipe, causing corrosion and wax precipitation of pipe, and so on. Therefore, before trial-production we should find a way to break the emulsion which is made of residual acid and crude oil and then dehydrate it. In order to measure the demulsification effect and time of the mixed emulsion, demulsification experiments of emulsion of crude oil and three different spent acids with different concentrations are conducted in the laboratory. The spent acids include gelled acids, cross-linked acids, insitu gelled acids which are widely used in the field. Through analyzing all the impact factors, the results show that the demulsification efficiency of gelled acid is the best, followed by cross-linked acid, and the efficiency of in-situ acid is the worst. At the simulated bottom hole temperature of 90℃, the dehydration rate after demulsification of emulsion of crude oil and spent gelled acids is over 98%. The lower the acid concentration is, the better the demulsification efficiency will be. This feature is most obvious when in-situ acids are used. The longer the time taken, the better the demulsification efficiency will be. But the demulsification ends after 90 min.The demulsification is fast and the dehydration rate is high at high temperatures. However, with the production of the well, crude oil flows to the bottom hole from the reservoir and the temperature declines, so the dehydration rate may decrease.