阳离子表面活性剂在不同砂岩表面的吸附与吸附焓变研究

Adsorption and adsorption enthalpy of cationic surfactant on different sandstone surface

姚同玉 姚风英 李继山

YAO Tongyu YAO Fengying LI Jishan

中国石油大学石油工程学院，山东东营　257061 胜利油田有限责任公司地质科学研究院，山东东营　257015

College of Petroleum Engineering in China University of Petroleum, Dongying 257061, China Geological Scientific Research Institute of Shengli Oilfield Company Ltd., Dongying 257015, China

驱油过程中，阳离子表面活性剂不仅能够降低油水界面张力，而且能够改变岩石表面的润湿性。为了加深对阳离子表面活性剂与砂岩表面作用机理的认识，用紫外分光光度法测定了阳离子表面活性剂在不同润湿性砂岩表面的吸附量，并利用相应的数学公式计算了吸附焓变。吸附量的测定说明阳离子表面活性剂在砂岩表面的吸附符合Langmuir吸附规律，不同润湿性砂岩表面的饱和吸附量不同，油砂表面的饱和吸附量最大，亲油表面的饱和吸附量中等，亲水表面的饱和吸附量最小。吸附焓变与吸附量相对应，油砂表面吸附焓变最大，亲油表面的吸附焓变中等，亲水表面的吸附焓变最小。这说明阳离子表面活性剂与油砂表面的作用最强，有利于改变储层岩石表面的性质，提高洗油效率。

During the process of oil displacement, cationic surfactant can not only be used to lower the oil-water interfacial tension, but can be used to change the wettability of rock surface. In order to deeply understand the mechanism of action between cationic surfactant and sandstone surface, the ultraviolet spectrophotometry is applied to measure the adsorption capacity of cationic surfactant on the sandstone surface of different wettability, as well as the adsorption enthalpy is calculated according to related mathematical formula. The measurement indicates that the adsorption of cationic surfactant on sandstone surface accords with the Langmuir adsorption law. The saturated adsorption capacity of cationic surfactant on different sandstone surface varies a lot: the saturated adsorption capacity on oil sand surface reaches the highest, that on the oil wetted surface is moderate, and that on the water wetted surface is the lowest. The adsorption enthalpy is consistent with the adsorption capacity: the adsorption enthalpy on oil sand surface is the most, that on the oil wetted surface is moderate, and that on the water wetted surface is the lowest. This shows the action between cationic surfactant and oil sand surface is the strongest, which is favorable for changing the surface properties of reservoir rock and improving oil displacement efficiency.