阳离子/非离子复合表面活性剂改变油湿性砂岩表面润湿性机制

Mechanistic study on wettability alteration of oil-wet sandstone surface using mixed cationic-nonionic surfactants

通过表面张力、接触角及Zeta电位测量首次研究并提出阳离子/非离子复合表面活性剂十六烷基三甲基溴化铵(CTAB)/辛基苯聚氧乙烯醚(TX-100)改变油湿性砂岩表面润湿性的吸附模型及机制。结果表明:阳离子/非离子复合表面活性剂CTAB/TX-100改变油湿性砂岩表面润湿性的效果比单一阳离子表面活性剂CTAB及非离子表面活性剂TX-100的效果更显著;CTAB与TX-100间存在良好的协同效应,CTAB分子预先吸附在油湿性砂岩表面充当锚粒子,TX-100分子通过疏水作用与其形成聚集体,从而提高了TX-100及CTAB在油湿性砂岩表面的吸附量;TX-100的存在也提高了CTAB与油湿性砂岩表面羧酸类物质形成离子对的能力,并使离子对的解吸附能力增强,因此改变油湿性砂岩表面润湿性的效果更显著。

The surface tension,contact angle and zeta potential measurements were used to study adsorption models for CTAB/TX-100 mixtures on oil-wet sandstone surface and mechanism for wettability alteration of oil-wet sandstone surface using mixed cationic-nonionic surfactants.It is found that the mixed cationic-nonionic surfactants CTAB/TX-100 show better performance in changing wettability of oil-wet sandstone surface than single CTAB and TX-100.The CTAB and TX-100 present good synergistic effects.The pre-adsorbed CTAB molecules act as anchors on the oil-wet sandstone surface,allowing TX-100 molecules to for^n mixed aggregates with them through chain-chain interactions,which results in the promotion of TX-100 and CTAB adsorption on oil-wet sandstone surface.Meanwhile,the ability of CTAB for forming ion pairs with carboxylic acid substances can be promoted by TX-100.And the adsorption and desorption capability of ion pairs are enhanced as well.Therefore,the mixed cationic-nonionic surfactants show better effect on wettability alteration of oil-wet sandstone surface than single surfactants.