A novel level set‐based approach is presented to calculate in situ contact angle distribution, θ, from pore‐scale immiscible fluids and rock configuration directly imaged with micro‐computed tomography (micro‐CT) techniques. We first identify interfaces of the fluid‐fluid and fluid‐solid by their zero level set functions. This is accomplished by reinitializing the level set functions with a signed distance function. Then the three‐phase contact line is determined at the crossover of the two zero level set functions that represent the two interfaces. The normal vectors of both surfaces are calculated directly using the two level set functions, and the contact angle is found from the dot product of these vectors where they meet at the contact line. We first validated our newly proposed method for the semianalytically calculated fluid configurations in a 2‐D tube and then tested the algorithm on a synthetic spherical oil droplet residing on a tilted flat solid surface where the contact angle is analytically defined. It was then used to measure the in situ contact angle of droplets directly imaged by micro‐CT, and the results are compared with the manually and other available automatically measured results. Compared with other available automatic approaches, our approach is mathematically well defined, and it does not require any other complicated tuning procedures for surface smoothing. This proposed approach allow us to accurately characterize local in situ pore‐scale wettability, which is essential to model multiphase flow in porous media and eventually help us to design and assess optimal processes, such as hydrocarbon recovery and carbon dioxide storage.

中文翻译：

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基于水平集法的原位接触角自动测定

提出了一种新的基于水平集的方法来计算原位接触角分布 θ，从孔隙尺度的不混溶流体和岩石构造直接用显微计算机断层扫描 (micro-CT) 技术成像。我们首先通过它们的零水平集函数来识别流体 - 流体和流体 - 固体的界面。这是通过使用带符号距离函数重新初始化水平集函数来实现的。然后在代表两个界面的两个零水平集函数的交叉处确定三相接触线。两个表面的法向量直接使用两个水平集函数计算，接触角是从这些向量在接触线相交处的点积中找到的。我们首先验证了我们新提出的用于在 2-D 管中进行半分析计算流体配置的方法，然后在位于倾斜平坦固体表面上的合成球形油滴上测试该算法，其中接触角是解析定义的。然后将其用于测量通过微 CT 直接成像的液滴的原位接触角，并将结果与​​手动和其他可用的自动测量结果进行比较。与其他可用的自动方法相比，我们的方法在数学上定义良好，并且不需要任何其他复杂的表面平滑调整程序。这种提议的方法使我们能够准确地表征局部的原位孔隙尺度润湿性，