油湿灰岩储层中季胺类物质对周期注水开发效果的影响

Effect of quaternary ammonium polymer on production behaviors of low-permeability and oil-wet limestone reservoir in cyclic water-flooding stage

周期注水是开发灰岩储层低渗透基质中原油的一种有效方法,但对于亲油储层效果较差。对基质含水饱和度变化特征进行了分析,建立了基质含水饱和度变化特征方程,提出了周期注水与润湿反转技术相结合的开采方式。利用油湿灰岩裂缝模型,在注入水中加入低浓度具有润湿反转能力的季胺类物质———十六烷基三甲基溴化铵(CTAB)进行了周期注水室内模拟研究。结果表明,CTAB可使油湿灰岩储层的表面性质发生明显变化,基质毛管的自吸及滞水排油能力增强,周期注水开发效果明显改善。

The cyclic water-flooding method is effective for development of oil in low-permeability matrix of limestone reservoir and unsuitable for the oil-wet reservoir. The changing characters of matrix water saturation were analyzed, and the equation for describing the change of matrix water saturation was derived. The laboratory experiment on cyclic water-flooding was made with oil-wet limestone reservoir models by adding cetyl trimethylammonium bromide (CTAB) with wettability alteration and low concentration into the injected water. The results showed that the surface property of oil-wet limestone reservoir changed towards that of water-wet reservoir greatly, and the capabilities of capillary imbibition, water storage and oil displacement were enhanced by using CTAB. The efficiency of cyclic water-flooding could be improved considerably.