表面活性剂吸附引起的硅石润湿性改变

WETTABILITY ALTERATION OF SILICA INDUCED BY SURFACTANT ADSORPTION

用两相滴定法测定了十六烷基三甲基溴化铵(CTAB)和十二烷基苯磺酸钠(SDDBS)在水湿和油湿硅石(SiO_2)上的吸附量,考察了电解质和pH值对吸附量的影响,用Amott/USBM法测定了这两种表面活性剂引起的砂岩岩样润湿性改变。测定结果表明,阳离子活性剂比阴离子活性剂更容易吸附在水湿硅石表面,导致硅石水湿性明显减弱甚至变为油湿。无机电解质使阴离子活性剂在硅石上的吸附量显著增加,Ca^(2+)与阴离子活性剂间的络合作用有可能使硅石表面从水湿向油湿转化。pH值对CTAB和SDDBS在硅石上的吸附量有相反的影响。

The adsorption of surfactants CTAB and SDDBS on silica under different conditions is measured by a two-phase titration and the wettability of the core samples of sandstone caused by surfactant adsorption-by the combined Amott/USBM method. The cationic surfactant, CTAB, is more readily adsorbed on the surfaces of water-wet silica than the anionic, SDDBS, making the surfaces less water-wet or even oil-wet. Inorganic electrolytes enhance the adsorption of SDDBS on silica significantly and change the surfaces from water-wet to oil-wet. The effects of pH values on the adsorption of the two surfactants are opposite. All the results are in good agreement with the results obtained from the zeta potential measurements according to the concept of water film stabilization.