Deng Xiao, Zhou Xianmin, Kamal Muhammad Shahzad, Hussain Syed Muhammad Shakil, Mahmoud Mohamed, Patil Shirish
Department of Petroleum Engineering, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
Center for Integrative Petroleum Research, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
Molecules. 2022 Feb 10;27(4):1195. doi: 10.3390/molecules27041195.
Static contact angle measurement is a widely applied method for wettability assessment. Despite its convenience, it suffers from errors induced by contact angle hysteresis, material heterogeneity, and other factors. This paper discusses the oil drop spreading phenomenon that was frequently observed during contact angle measurements. Experimental tests showed that this phenomenon is closely related to surfactants in the surrounding phase, the remaining oil on the rock surface, and oil inside the surrounding phase. A modified contact angle measurement process was proposed. In the modified method, deionized water was used as the surrounding phase, and a rock surface cleaning step was added. Subsequent measurements showed a very low chance of oil drop spreading and improved precision. A further comparison study showed that, when the surrounding phase was deionized water, the measured contact angle values tended to be closer to intermediate-wet conditions compared to the values measured in clean surfactant solutions. This difference became more significant when the surface was strongly water-wet or strongly oil-wet. As a result, the developed process has two prerequisites: that the in-situ contact angle values inside surfactant solutions are not required, and that the wettability alteration induced by the surfactant solution is irreversible.
静态接触角测量是一种广泛应用于润湿性评估的方法。尽管其具有便利性，但它会受到接触角滞后、材料不均匀性和其他因素引起的误差影响。本文讨论了在接触角测量过程中经常观察到的油滴铺展现象。实验测试表明，这种现象与周围相中存在的表面活性剂、岩石表面残留的油以及周围相内部的油密切相关。本文提出了一种改进的接触角测量方法。在改进后的方法中，使用去离子水作为周围相，并增加了岩石表面清洁步骤。后续测量表明，油滴铺展的可能性非常低，测量精度得到了提高。进一步的对比研究表明，当周围相为去离子水时，与在清洁表面活性剂溶液中测量的值相比，测量得到的接触角值更接近中间润湿性条件。当表面为强水湿或强油湿时，这种差异变得更加显著。因此，所开发的方法有两个前提条件：不需要表面活性剂溶液内部的原位接触角值，以及表面活性剂溶液引起的润湿性改变是不可逆的。
