The effect of capillary pressure on multiphase flow is described by the capillary pressure gradient term in the fractional flow equation. This term is typically neglected during core‐flooding experiments, as it is not easily accessible. However, the capillary pressure is not constant during core flooding owing to a capillary pressure discontinuity at the core outlet. By imaging spatial fluid distributions under two‐phase steady‐state flow, we determine in situ phase saturations and capillary pressures from interfacial curvature measurements along an entire core, thus achieving the assessment of the capillary pressure gradient and its influence on multiphase flow. We demonstrate how the pore‐scale capillary pressure gradient affects multiphase flow and, in turn, the core‐scale relative permeability measurements. Further, an alternative approach to determining relative permeability from a single fractional flow experiment is proposed. The approach provides a range of relative permeabilities for a single fractional flow experiment and does not require capillary‐end correction, as the formulation directly accounts for the effect of capillary pressure on the flow.

中文翻译：

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毛细作用对分流中相对渗透率的影响

毛细管压力对多相流的影响通过分数流方程中的毛细管压力梯度项来描述。该术语在岩心驱替实验中通常被忽略，因为它不容易获得。但是，由于岩心出口处的毛细管压力不连续，因此在岩心驱替期间，毛细管压力不是恒定的。通过对两相稳态流下的空间流体分布进行成像，我们就地确定了相角饱和度和沿整个岩心的界面曲率测量产生的毛细管压力，从而实现了对毛细管压力梯度及其对多相流影响的评估。我们证明了孔隙尺度的毛细管压力梯度如何影响多相流，进而影响了岩心尺度的相对渗透率测量。此外，提出了一种从单个分流实验确定相对渗透率的替代方法。该方法为单次分流实验提供了一定范围的相对渗透率，并且不需要毛细管末端校正，因为该配方直接考虑了毛细管压力对流动的影响。