阴离子型表面活性剂改变油湿性砂岩表面润湿性机理

Wettability Changing Mechanism of Oil-wet Sandstone Surface by Anionic Surfactant

石 鑫 许艳艳 伍亚军 吴贝贝 席玲慧 侯宝峰

SHI Xin XU Yanyan WU Yajun WU Beibei XI Linghui HOU Baofeng

研究表面活性剂改变岩石表面润湿性的机理对油田现场施工具有一定的理论指导意义。通过红外光谱、形貌扫描成像、Zeta 电位、固体表面振荡频率和接触角等的测定，研究了阴离子型表面活性剂十二烷基醇聚氧乙烯醚硫酸钠-1（PES）改变油湿性砂岩表面润湿性的机理。结果表明，与油湿性石英粉的红外光谱相比，PES处理后的石英粉红外谱图中具有S—O键、亚砜S=O键和砜—SO2—键的拉伸振动峰，说明“吸附”为 PES 改变油湿性砂岩表面润湿性的机理。由于 PES 吸附在油湿性石英片表面，使得石英片表面较为平坦，平均粗糙度大大减小。未经 PES 处理的油湿性石英颗粒的 Zeta 电位为-4.2 mV，用 PES 处理样品的 Zeta 电位值随着 PES 浓度的升高而降低，最终趋于平衡。PES与带负电岩石表面的静电排斥力使得PES以微弱的分子间作用力吸附在砂岩表面。随着 PES 浓度的增加，石英晶体表面的共振频率降幅越来越大，即 PES 分子在岩石表面的吸附量越来越大。另外，未经 PES 处理的油湿性石英片原始接触角为 140°，经过 PES 处理的油湿性石英片对应的接触角为109°。随着 PES 的加入，表面活性剂疏水链与原油组分的疏水端形成双层吸附结构，此时表面活性剂亲水头基裸露在外面，使得接触角逐渐降低，从而改变了固体表面的润湿性。

Research on the mechanism by which surfactants change the wettability of rock surfaces has certain theoretical guiding significance for on-site construction in oilfield. The wettability changing mechanism of oil-wet sandstone surface by anionic surfactant sodium lauryl alcohol polyoxyethylene ether sulfate-1（PES）was studied through the determination of infrared spectrum， morphological scanning imaging，Zeta potential，solid surface oscillation frequency and contact angle. The results showed that compared with the infrared spectrum of oil-wet quartz powder，the infrared spectrum of quartz powder treated with PES had stretching vibration peaks of S—O bond，sulfoxide S=O bond and sulfone —SO2— bond，indicating that“adsorption”was the wettability changing mechanism of oil-wet sandstone surface by PES. Due to the adsorption of PES on the surface of oil-wet quartz wafer，the surface of quartz wafer was relatively flat and the average roughness was greatly reduced. The Zeta potential of untreated oil-wet quartz particles was -4.2 mV. The Zeta potential value of the sample treated with PES decreased with the increase of PES concentration，and finally tended to equilibrium. The electrostatic repulsion force between PES and negatively charged rock surface made PES adsorb on the sandstone surface with weak intermolecular force. As the concentration of PES increased，the resonance frequency decreasing amplitude of quartz crystal surface became larger and larger，that was，the adsorption amount of PES molecules on the rock surface became larger and larger. In addition，the original contact angle of untreated oil-wet quartz wafer was 140° ，while the corresponding contact angle of oil-wet quartz wafer treated with PES was 109° . With the addition of PES，a double-layer adsorption structure formed between the hydrophobic chain of surfactant and the hydrophobic end of crude oil components. At this time，the hydrophilic head group of surfactant exposed outside，making the contact angle gradually decrease， thus changing the wettability of solid surface.

10.19346/j.cnki.1000-4092.2024.04.015