海上油田注水井复合纳米降压增注技术研究

为解决海上油田注水井压力升高过快，欠注现象严重的问题，在室内复配了一种适合于海上油田注水井的复合纳米降压增注物料体系。进而评价了该体系的稳定性、界面活性、防膨性能、改变岩石润湿性能以及降低微粒运移伤害能力，还通过岩心驱替实验评价了其降压增注效果。结果表明，该复合纳米降压增注体系具有良好的稳定性和界面性能，在储层温度下放置50 d后界面张力仍然可以稳定在10-2 mN/m的数量级。体系对岩心粉末的防膨率可以达到96.7%，并且可以有效改变岩石表面润湿性。使用该复合纳米降压增注物料处理后的驱替液颗粒总数以及粒径中值都明显降低，说明其具有较好的降低微粒运移堵塞的可能性。岩心驱替实验结果表明，经增注措施处理以后压力降低率均可以达到35%以上，可见复合纳米降压增注物料体系具有明显的减阻效果，能够满足海上油田注水井长期降压增注的需要。

Study on the Technology of Composite Nano Depressurization and Augmented Injection for Water Injection Well in Offshore Oil Field

In order to solve the rapid increase of pressure and under injection of water injection wells in offshore oilfeld, a composite nano depressurization and augmented injection system for water injection well in offshore oilfeld was developed. The stability, interfacial activity, anti-swelling property, change of the rock wettability, and the ability to reduce the migration and damage of the particles were evaluated. Meanwhile, the effect of depressurization and augmented injection was demonstrated by the displacement experiment. The results show that the composite nano depressurization and augmented injection has a good stability and interfacial property, and the interfacial tension can be stabilized at 10-2 mN/m when placed under the simulated reservoir temperature for 50 days. The anti-swelling rate of core powder can reach 96.7%, which can effectively change the surface wettability of rock. The total number of the particles and the median diameter of the flooding particles were signifcantly decreased after treating by the system, it means the possibility of blockage caused by particle migration can be reduced to some extent. Core flooding experiments showed that the depressurization rate reaches more than 35% after taking the augmented injection measure. It can be concluded that the drag reducing effect of the composite nano depressurization and augmented injection system is obvious, and can meet the needs of longterm depressurization and augmented injection of water injection wells in offshore oilfeld.