We encounter three-phase flow in porous media within a range of settings, such as enhanced oil recovery, geologic CO₂ sequestration, and groundwater remediation. While an abundance of studies has been performed on the behavior of two fluid phases (e.g. oil/water or air/water) in porous media, relatively little information exists for three-phase flow systems (e.g. oil/water/air). This work explores the relationships between capillary pressure (P_c), saturation (S) and fluid-fluid interfacial area (a) for water-wet three-phase flow systems where water is the wetting phase, oil is the intermediate-wet phase, and air (or gas) is the non-wetting phase. Specifically, we examine whether the P_c-S-a relationships exhibit hysteresis during drainage and imbibition cycles. We present data collected via x-ray microtomography resulting in high-resolution three-dimensional images of the fluid configurations for varying degrees of saturation. Among the findings of the study (based on the available data), we highlight that (1) the P_c-S-a relationship is non-hysteretic for both the oil-water fluid pair, and the air-oil fluid pair, and (2) that this same relationship is independent of the initial water saturation at the point of air injection. This finding suggests that both the oil-water and air-oil fluid pairs in a three-phase system can be adequately described by the thermodynamics-based theory originally proposed by Hassanizadeh and Gray (1993), as is the case for the equivalent two-phase system.

我们在一定范围内的多孔介质中遇到三相流，例如提高采油率，地质CO ₂固存和地下水修复。尽管已经对多孔介质中两个流体相（例如油/水或空气/水）的行为进行了大量研究，但对于三相流系统（例如油/水/空气）的信息却很少。这项工作探索了水-湿三相流系统中毛细压力（P _c），饱和度（S）和流体-流体界面面积（a）之间的关系，其中水是湿相，油是中湿相，空气（或气体）是非润湿阶段。具体来说，我们检查P _c是否-小号-一个关系中的排水和渗吸周期表现出滞后现象。我们介绍通过X射线显微断层摄影术收集的数据，从而获得不同饱和度的流体构造的高分辨率三维图像。在研究结果（基于可用数据）中，我们强调（1）P _c - S - a对于油-水流体对和空气-油流体对，这种关系都是非滞后的，并且（2）这种相同的关系与注气点的初始水饱和度无关。这一发现表明，三相系统中的油-水和空气-油流体对都可以由Hassanizadeh和Gray（1993）最初提出的基于热力学的理论来充分描述，等效的两相流体就是这种情况。相系统。