添加纳米SiO_2颗粒的泡沫表面性质及调剖性能

Experimental study on interface properties and oil displacement efficiency of foams stabilized by SiO_2 nanoparticles

泡沫驱在三次采油中取得了很好的开采效果,但是泡沫的稳定性制约其应用,在表面活性剂中加入纳米SiO_2以提高泡沫的稳定性。利用Tracker全自动界面流变仪测量复配体系的表面张力和界面扩张黏弹模量;利用微观驱油试验模型分析添加纳米SiO_2泡沫体系的驱油机制并与普通泡沫体系进行对比;利用岩心试验研究纳米SiO_2含量对泡沫体系驱油效果的影响。结果表明:随着纳米颗粒质量分数的增加,泡沫的稳定性和界面扩张黏弹模量均增加;泡沫稳定性的增强可以有效避免气液分离现象,使气泡更好地圈闭气体,提高泡沫的封堵效率,增加波及体积;界面扩张黏弹模量增强可以加强对孔道壁面油的挤压和携带作用;随着纳米SiO_2质量分数的增加,含油岩心的采收率及压差均上升,与普通泡沫驱比采收率可提高25%以上。

Foam flooding is proven to be an effective technique for improve d oil recovery, but the stability of foam has limited its application. Nano-SiO2 is therefore added into surfactant solutions to increase the foam＇s stability. In this study, the sur-face tension and surface dilatational properties of a combined foam system SiO2＋SDS were measured by a Tracker Interfacial Rheometer, and the mechanism of the foam flooding was investigated using a microscopic model in comparison with the SDS foam flooding. The effect of the nano-SiO2 agent on oil displacement was also studied via core flooding experiments. The experimental results show that the stability of the foam and the surface dilatational viscoelasticity modules increase with the increase of mass fraction of SiO2 nanoparticles. The enhanced foam stability can effectively prevent separation of gas and liq-uid, and increase the efficiency of foam plugging and sweeping. The enhanced surface dilatational viscoelasticity modules can increase oil displacement efficiency as demonstrated in the microscopic model experiments. The core flooding results show that both the oil recovery and the pressure drop increase with the increase of nano-SiO2 mass fraction, and the oil recovery efficiency is 25% higher than that of the SDS foam flooding.