碱/表面活性剂/聚合物三元复合驱采油井高黏稳定乳状液成因探讨

Forming Mechanism of Stable Emulsion with High Viscosity in Production Well duiring Alkail-Surfactant-Polymer Flooding

为揭示碱/表面活性剂/聚合物三元复合驱采油井高黏度乳状液的成因,分析了室内物理模拟驱油及矿场采出液中油相黏度特点,考察了外力作用、化学剂浓度和类型、含水率和原油组分对乳状液稳定性及黏度的影响规律,探讨了相关作用机理。结果表明,在适宜的含水率(低于50%)条件下,含有极低浓度化学剂的采出水与原油通过强烈的外力作用(均化器转速超过6000 r/min),可形成高黏度稳定乳状液,原油中的沥青质是形成高黏度乳状液的关键物质。在模拟地层水中外加浓度较低的化学剂(重烷基苯磺酸盐、碱或部分水解聚丙烯酰胺)时,无论哪种类型的化学剂体系与原油在含水50%、均化器转速11000 r/min下形成的乳状液放置90 d后仍不分相,黏度均超过100 m Pa·s;当模拟地层水中外加化学剂浓度较高时,高黏度稳定乳状液不易形成,乳状液放置7 d后,析水率均大于85%,黏度均低于100 m Pa·s,外加的重烷基苯磺酸盐和部分水解聚丙烯酰胺等主要起破乳剂的作用。

In order to discover the reason of stable emulsion with high viscosity from ASP production well, on the basis of analyzing oil phase viscosity difference from core and production well, the affecting factors of emulsion stability and viscosity were investigated by changing stirring rate and chemical type and concentration and water cut and petroleum composition. In addition, the related mechanism was discussed. The results showed that high viscosity emulsion was formed by mixing produced water with ultra-low concentration chemical agents and crude oil using strong acting force（stirring rate of homogenizer 〉6000 r/min） at certain water cut （ ~〈 50% ）, and asphaltene in crude oil was the key factor to the formation of stable emulsion with high viscosity. When chemical agents （heavy alkyl benzene sulfonate, alkali or HPAM）with low concentration were added in the simulated formation water, the viscosity of crude oil-water emulsion, prepared at water cut of 50% and at the stirring rate of 11000 r/min, was over 100 mPa. s and phase separation didnont appear after 90 days; however, the addition of chemical agents with high concentration in the simulated formation water was unfavourable for the formation of high viscosity emulsion , and viscosity of emulsion was less than 100 mPa. s and water separating proportion was over 85% after 7 days, which was mainly because that the added heavy alkyl benzene sulfonate and HPAM mainly played the role of de-emulsifier.