Macroscopic observations of two-phase flow in porous rocks are largely affected by the heterogeneity in continuum properties at length scales smaller than a typical laboratory sample. The ability to discriminate among the rock properties at the origin of the heterogeneity is key to the development of numerical models to be used for prediction. Here, we present a capillary equilibrium model that represents spatial heterogeneity in dual-porosity porous media in terms of the capillary entry pressure, $1/\alpha ,$ and the irreducible wetting phase saturation, $S_{\mathrm{ir}}$. Both parameters are used to scale local capillary pressure curves by using three-dimensional imagery acquired during multi-rate gas/liquid drainage displacements. We verify the proposed approach by considering the case study of a dual-porosity limestone core and use the spatial variation in $S_{\mathrm{ir}}$ as proxy for microporosity heterogeneity. The latter places potentially next-to-leading order controls on the observed fluid saturation distribution, which is strongly correlated to the distribution of $1/\alpha$. While microporosity is by and large uniform at the observation scale on the order of 0.1 cm${}^3,$ the spatial correlation of $1/\alpha$ is on the order of 1 cm and is therefore not statistically represented in the volume of typical laboratory core samples.

多孔岩中两相流的宏观观测在很大程度上受连续体特性非均质性的影响，其长度尺度小于典型的实验室样品。区分非均质性起源处的岩石特性的能力是开发用于预测的数值模型的关键。在这里，我们介绍了一个毛细管平衡模型，该模型代表了毛孔进入压力方面的双孔隙多孔介质中的空间异质性，$\mathrm{1个}/\alpha ，$ 和不可减少的润湿相饱和度， ${\mathrm{小号}}_{\mathrm{ir}}$。通过使用在多速率气/液排放位移过程中获取的三维图像，这两个参数都可用于缩放局部毛细管压力曲线。我们通过考虑双孔隙石灰岩岩心的案例研究来验证所提出的方法，并使用${\mathrm{小号}}_{\mathrm{ir}}$作为微孔异质性的代理。后者在观察到的流体饱和度分布上放置了潜在的次于前导的阶跃控制，它与流体的饱和度分布密切相关。$\mathrm{1个}/\alpha$。虽然微孔在观察范围内大致均匀，但约为0.1厘米${}^3，$ 的空间相关性 $\mathrm{1个}/\alpha$ 大约为1厘米，因此在典型的实验室核心样品的体积中没有统计学上的代表。