新疆油田复合驱过程中的乳状液类型转变

为分析新疆油田部分采油井二元复合驱油中出现高黏度(3000 m Pa·s)油包水型乳状液现象的原因,室内模拟化学驱中表面活性剂/聚合物二元复合体系与原油的乳化过程,研究了矿化度、油水比、表面活性剂浓度和地层水稀释对乳状液类型的影响,建立了在岩心驱油过程中乳状液的转变模型。研究结果表明,当矿化度较低(100 mg/L Na Cl)时,乳状液主要为水包油型;随着矿化度的增大,水包油型乳状液的稳定性变差,当矿化度达到10 g/L时,乳状液开始向油包水型转变。油水比为1∶9和3∶7时,乳状液主要为水包油型;当油水比为5∶5、表面活性剂加量为500 mg/L时,乳状液为油包水型。随着地层水稀释比例的增加,乳状液由水包油型向油包水型转变。室内岩心驱油实验结果表明,随着二元体系的注入与推进,矿化度升高,表面活性剂浓度降低,油水比变大,导致乳状液产生了由水包油型向油包水型的转化。

Type Transformation of Emulsion during Surfactant/Polymer Flooding in Xinjiang Oilfield

In order to analyze the appearance of water-in-oil type emulsion with high viscosity (3000 mPa?s) during some binary flooding production wells in Xinjiang oilfield, the emulsification process of surfactant/polymer compound system and crude oil in chemical flooding was simulated in laboratory. The effect of salinity, oil-water ratio, surfactant concentration and the dilution of underwater on the type of emulsion was studied. The model of emulsion conversion was also built during core flooding. The results showed that when the salinity was lower (100 mg/L NaCl), the main emulsion type was oil-in-water. When the salinity was 10 g/L, the water-in-oil emulsion formed. The emulsion type was oil-in-water when the ratio of oil to water was 1:9 and 3:7. Once oil-water ratio reached 5:5 and the concentration of surfactant was 500 mg/L, water-in-oil emulsion formed. With the increase of groundwater, the oil-in-water emulsion changed to water-in-oil emulsion. The flooding experiment results showed that during the propulsion process of binary system, the salinity and water-oil ratio increased, the concentration of surfactant reduced, which made emulsion change from oil-in-water type to water-in-oil type.