无碱与含碱化学体系驱替稠油特征比较

Comparative study between alkali-free and alkali-containing chemical systems for recovering heavy oil

韩玉贵 丁名臣 刘义刚 邹剑 赵鹏 王业飞

中海石油（中国）有限公司天津分公司渤海石油研究院，天津 300452 中国石油大学（华东）石油工程学院，山东 青岛 266580

Bohai Oilfield Research Institute, Tianjin Branch of CNOOC Ltd., Tianjin 300452, China College of Petroleum Engineering, China University of Petroleum, Qingdao 266580, China

稠油含碱体系化学驱能够显著提高采收率，但是碱的加入会带来结垢、采出液破乳难等问题，因此，人们逐渐考虑用无碱体系驱替稠油。当前关于2类体系驱替稠油特征和机理差异的研究较少，为了明确无碱和含碱化学体系驱替稠油差异，文中主要针对表面活性剂￣聚合物（SP）和碱￣聚合物（AP）体系开展了界面张力（IFT）、乳化性能和驱油特征研究。结果表明，SP和AP驱替稠油机理存在显著不同，即前者通过超低IFT形成油在水中乳化型（O/W）乳状液驱油，而后者与稠油没有达到超低IFT，形成水在油中乳化型（W/O）的乳状液。驱油结果表明，化学体系驱替稠油能力由强到弱依次为：AP、泡沫、SP、聚合物（P）、碱（A）、表面活性剂（S）。这说明：P的加入（扩大波及体积）是提高稠油采收率的前提，然后S和A才能充分发挥其超低IFT和乳化作用；气泡辅助的SP驱￣泡沫驱是当前无碱复合体系驱替稠油的较好的注入方式，是接替AP驱的重要技术；与泡沫驱相比，单一SP驱存在对化学药剂的潜在浪费。

The chemical flooding of heavy oil with alkali-containing system can significantly improve oil recovery, but the addition of alkali will lead to scaling and the difficulty of demulsification. Therefore, people gradually consider replacing it with alkali-free system, but there are few reports on the difference of characteristics and mechanism between those two systems. To clarify those differences between alkali-free and alkali-containing chemical systems in recovering heavy oil, the interfacial tension(IFT), emulsification behaviors and oil displacement characteristics of surfactant-polymer(SP) and alkali-polymer(AP) systems were experimentally studied. The results show that there are significant differences in the mechanism of heavy oil recovery between SP and AP: the former is mainly driven by ultra-low IFT and the formation of O/W emulsion, while the latter could hardly reach ultra-low IFT and mainly forms W/O emulsion. The recovery data proves that the ability of the chemical system to displace heavy oil from strong to weak is: AP, foam, SP, polyer, alkali, surfactant, which indicates that the sweep volume enlargement is the prerequisite for improving heavy oil recovery, then, the ultra-low IFT and emulsification mechanism can give full play; on the other hand, foam flooding is the best strategy for displacing heavy oil by the alkali-free systems, which is an important method to replace the AP method. Compared with the foam flooding, the single SP flooding has potential waste to the chemical agent.

10.6056/dkyqt202101024