稠油O/W型乳状液的低温稳定性

Stability of Heavy Oil-in-Water Emulsion at Low Temperature

安云朋 敬加强 刘雪健 王雷振 田 震

AN Yun-Peng JING Jia-Qiang LIU Xue-Jian WANG Lei-Zhen TIAN Zhen

绥中36-1稠油50℃与3℃的黏度分别为1251.5与417518.1 mPa·s，在3~60℃范围内表现为牛顿流体，20℃密度为0.953 g/cm3，属重质普通稠油。用非离子型表面活性剂BJN-01作为乳化剂，制备了不同乳化剂加量（0.3%~0.7%）及油水比（8:2~6:4）的稠油O/W型乳状液。采用恒温静置、流变测量和微观影像分析方法，研究了乳化剂加量及油水比对该乳状液低温（3℃）静态及动态稳定性的影响。结果表明，O/W型乳状液3℃的静态稳定性随乳化剂加量的增大而明显提高；油水比6:4和7:3乳状液的分水率随静置时间延长而增大；油水比8:2的乳状液在制备完成后即发生油水两相分离，稳定性较差。在动态剪切2.0 h后，O/W型乳状液均发生了不同程度的聚集与聚并，油水比越高或乳化剂加量越低，聚集与聚并现象越显著。乳化剂加量0.5%、油水体积比6:4时，在动态剪切2.0 h内，O/W型乳状液表现为牛顿流体，3℃下的黏度小于50 mPa·s；乳化剂加量0.7%、油水比7:3的O/W型乳状液3℃下的黏度小于100 mPa·s，具有良好的低温静、动态稳定性，对管道低温采输及停产停输再启动有良好的适应性。

The viscosity of heavy oil in Suizhong36-1 (SZ36-1) oilfield was 1251.5 mPa·s and 417518.1 mPa·s at 50℃ and 3℃ respectively. The heavy oil presented Newtonian fluid during 3—60℃, and the density was 0.953 g/cm3at 20℃ which belonged to ordinary heavy oil. The SZ36-1 heavy oil-in-water emulsions with different volume ratios of oil and water (8:2—6:4) and dosages of emulsifier (0.3%—0.7%) were prepared using non-ionic surfactant BJN-01 as emulsifier. The effect of oil and water ratio and emulsifier concentration on the stability of oil-in-water emulsion was studied through thermostatic standing, rheological experiment and microscopic observation at low temperature (3℃). The results showed that the stability of O/W emulsion improved significantly with increasing emulsifier concentration. Water separation rate of the emulsion with 6:4 and 7:3 oil and water ratio increased when the time extended. When oil and water ratio was 8:2, the emulsion was unstable, oil and water phase was separated immediately after preparation. Flocculation and coalescence took place in O/W emulsions at different degrees after dynamic shearing for 2 hrs. When the oil and water ratio was higher or emulsifier concentration was lower, the flocculation and coalescence was more significant. When the dosage of emulsifier was 0.5% and oil and water ratio was 6:4, the O/W emulsion showed Newtonian fluid, the viscosity of emulsion was less than 50 mPa·s, and when the dosage of emulsifier was 0.7% and oil and water ratio was 7:3, the viscosity of emulsion was less than 100 mPa·s after dynamic shearing for 2 hrs at 3℃. Therefore, the static and dynamic stabilities of these emulsions were perfect. The oil-in-water emulsion was suitable for transportation and restart-up of pipeline at low temperature.