Carbonate rock reservoirs are dominated by heterogeneity across a large and continuous range of spatial scales. We study the impact of heterogeneities on relative permeability and residual trapping for three carbonate rocks selected for their distinct spatial scales of rock texture. The Indiana limestone comprises millimeter‐scale heterogeneities, the Estaillades limestone consists of half‐centimeter‐scale heterogeneities, and the Edwards dolomite includes decimeter‐scale heterogeneity. Along with routine characterization of rock samples, steady‐state N₂–deionized water drainage relative permeability measurements are made for each rock at two distinct total flow rates, at least 1 order of magnitude apart. The variation in flow potential across the core results in observations of fluid distribution, core‐average relative permeability, and residual trapping obtained for a range of continuum‐scale capillary number . The relative permeability curves for all rocks shift to the right of the water saturation axis with increasing flow potential; the nitrogen relative permeability increases while the water relative permeability decreases. However, the magnitude of the shift depends on the spatial scale of heterogeneity. An inspection of 3D saturation distributions in the cores and estimation of the capillary numbers of flow shows that the rock with the largest heterogeneity is capillary flow dominated throughout the range of injection rates tested; observations in the Indiana and Estaillades carbonates traverse capillary to viscous dominated flow regimes, with commensurate flow rate dependence in the relative permeability. In all cases, residual trapping is poorly described by the Land model.

中文翻译：

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毫米至厘米尺度的非均质性对碳酸盐岩相对渗透率和圈闭的影响的观测

碳酸盐岩储层在较大范围和连续范围的空间尺度上均以非均质性为主。我们研究了非均质性对三种碳酸盐岩石相对渗透率和残余捕集的影响，这些碳酸盐岩石因岩石纹理的不同空间尺度而被选择。印第安纳州的石灰岩包括毫米级的非均质性，伊斯塔利亚德斯的石灰岩包括半厘米级的非均质性，爱德华兹的白云岩包括分米级的非均质性。除了对岩石样品进行常规表征外，还需要稳态N ₂–在两种不同的总流速（相距至少1个数量级）下，对每块岩石进行去离子水相对渗透率测量。穿过岩心的流动电位变化导致观察到的流体分布，岩心平均相对渗透率和在一定范围的连续尺度毛细管数下获得的残留捕集。随着流动势的增加，所有岩石的相对渗透率曲线都向水饱和轴的右侧移动。氮相对渗透率增加而水相对渗透率降低。但是，这种变化的幅度取决于异质性的空间尺度。检查岩心中的3D饱和度分布并估计毛细流动数表明，在测试的注入速率范围内，非均质性最大的岩石是毛细流动占主导地位。印第安纳州和埃斯塔利亚德斯州的碳酸盐岩横穿毛细管至粘性为主的流动状态，相对渗透率具有相应的流速依赖性。在所有情况下，Land模型都无法很好地描述残留陷阱。