微泡沫在高温高盐油藏中的驱油作用

Microfoam Flooding Effect in High Temperature and High Salinity Reservoir

针对普通泡沫在高温高盐油藏中稳定性弱、驱油效果差的问题,采用将气体和起泡剂溶液(5000 mg/L甜菜碱表面活性剂SL1+5000 mg/L黄原胶XG)同时注入填砂管泡沫发生器的方法制备了一种稳定性强、尺寸细微的微泡沫体系,即黄原胶稳定的微泡沫。通过微观可视化模型对比了普通微泡沫(5000 mg/L SL1)与黄原胶稳定的微泡沫在原油存在条件的下稳定性差异,分析了驱油机理,借助填砂管模型对比了两种微泡沫的驱油性能。微观实验结果表明:气泡液膜中吸附的黄原胶增加了微泡沫液膜厚度,有效抑制了气泡聚并和液膜排液,使黄原胶稳定的微泡沫具有更强的稳定性和耐油能力。微泡沫越稳定,微观波及体积越高、采油效率越高。微泡沫主要的驱油机理为直接驱替机理、乳化机理、同向液膜流动机理、逆向液膜流动机理。物模实验结果表明,在160 g/L矿化度、90℃条件下,黄原胶稳定的微泡沫驱的采收率可在水驱基础上提高22.9%,比普通微泡沫驱高15.2%。

Aimed at the problems of poor stability and worse oil displacement performance of common foam, a xanthan gum-stabilized microfoam with excellent stability and fine particle size was prepared by using a sandpack foam generator with co-flowing gas and foaming solution （5000 mg/L betaine surfactant SL1 ＋5000 mg/L xanthan gum）. Stability of the common microfoam （5000 mg/L SL1） and the xanthan gum-stabilized microfoam with the presence of a crude oil was studied and the displacement mechanism was analyzed by micromodel, the oil displacement performance of the microfoam was evaluated by sandpack flooding tests. The experimental results showed that xanthan gum-stabilized microfoam had better oil tolerance than common microfoam did, due to the adsorption of xanthan gum on the surface of the bubble, the absorption of xanthan gum in lamellas increased thickness of the microfoam lamella and inhibited bubble coalescence and liquid drainage. The displacement efficiency strongly depended on the stability of the microfoam, when the microfoam became more stable, the microscopic sweep volume became bigger and the oil recovery efficiency became higher. The main microscopic displacement mechanisms of microfoam flooding for enhanced oil recovery was that direct displacement, emulsification, co-current film flow and counter-current film flow. Xanthan gum-stabilized microfoam flooding increased oil recovery by 22.9%, which was 15.2% higher than that for common microfoam at salinity of 160 g/L and at the temperature of 90℃.