分别用十六烷基三甲基溴化铵(CTAB)和阳离子氟碳型表面活性剂FC911处理石英砂,然后用Washburn法测定处理后石英砂对水和油的接触角,研究两种阳离子表面活性剂对砂岩表面润湿性的影响。实验结果表明随着处理液CTAB浓度从0增至10000 mg/L,石英砂水相接触角由0°增至89°,再减至66°,表面从水湿变为中性润湿,再变为弱水湿。FC911浓度为10~1000 mg/L时,水相接触角由〉90°逐渐减小至89.7°;油相接触角由15.3°逐渐增至〉90°。石英砂表面由强油湿变为弱油湿后再变为中间气湿。较低浓度的FC911即可将石英砂表面转变为既疏水又疏油的中间气湿,最佳使用浓度为200 mg/L。
The effects of two surfactants on wettability of sandstone surface were studied by treating the quartz sand with hexadecyl trimethyl ammonium bromide(CTAB) and cationic fluorocarbon surfactant FC911 respectively and then measuring the contact angles according to Washburn's method.The results showed that with the concentration of CTAB solution increasing from 0 to 10000 mg/L,the air-water contact angles of quartz sand increased from 0° to 89° and then dropped to 66°,which meant the surface of the solid changed from water-wetting to neutral wetting,and then to weakly water-wetting.When the concentration of FC911 ranged from 10 to 1000 mg/L,the air-water contact angles decreased from 90° to 89.7°,while the air-oil contact angles increased from 15.3° to 90°.The wettability of the sand surface changed from strongly oil-wetting to weakly oil-wetting,and then to intermediate gas-wetting.The optimal concentration of FC911 was of 200 mg/L.