Experimental measurement and theoretical estimation of diffusion coefficients for multi-components fluid mixtures

扩散是流体混合物中质量的分子传递，它发生在存在浓度梯度的情况下，并倾向于消除浓度变化。当质量的传递是由热梯度引起的，它被称为热扩散或索雷特效应。在自然界和通过技术的许多重要过程中，这两种现象都起着至关重要的作用，即海洋中的热盐对流、火山熔岩、晶体生长过程、合金的凝固、同位素分离以及聚合物的表征和分离。值得注意的是，由于地球地热梯度的存在，烃（油）储层的组成受到扩散和索雷特效应的显著影响。目前，还没有可靠的理论方法来预测这些因素对油气储量的影响，这极大地阻碍了石油公司制定最佳采收率策略。通过了解和预测油藏组成分布中的扩散和Soret效应，这些公司可以更好地管理资源的最佳开发，实施高效的采油技术。本文将重点研究三元液体混合物在不同温度和浓度下的扩散系数和热扩散系数的实验测量和理论估计。这些实验结果将与申请人目前正在开发的用于研究多组分液体混合物热扩散过程的理论方法进行比较。

Diffusion is the molecular transport of mass in fluid mixtures, which occurs in the presence of a concentration gradient and tends to eliminate concentration variations. When the transport of mass is caused by a thermal gradient, it is known as thermodiffusion or the Soret effect. There are many important processes in nature and through technology where both these phenomena play a very crucial role, viz. thermohaline convection in oceans, volcanic lava, crystal growth processes, solidification of alloys, isotope separation, and the characterization and separation of polymers. Notably, due to the presence of the planet’s geothermal gradient, the composition of hydrocarbon (oil) reservoirs is significantly affected by both diffusion and the Soret effect. Currently, there is no reliable theoretical approach to predict the effects of these factors on hydrocarbon reserves, which is significantly hampering the development of optimal oil recovery strategies by oil companies. By understanding and predicting both diffusion and the Soret effect in the component distribution of oil reservoirs, these companies can better manage the optimal exploitation of resources to implement efficient oil recovery techniques. This proposal will focus on the experimental measurement and theoretical estimation of the diffusion and thermodiffusion coefficients for ternary liquid mixtures at different temperatures and concentrations. These experimental results will be compared with the theoretical approach that is currently being developed by the applicant to study the thermodiffusion process in multi-component liquid mixtures.