Our understanding and modelling of flow instabilities (e.g. viscous, gravitational) in the presence of geological heterogeneity is limited by a lack of experimental observations at relevant scales in consolidated media. Typically, small sample sizes (<50 mm diameter) restrict the scale of heterogeneity, and the development of unstable fingers may be damped by the sample boundaries. Furthermore, there is a lack of 3D dynamic data, resolved at a level to observe finger growth and interaction. To this end, we conduct a series of drainage & imbibition fluid-flow experiments with nitrogen and brine in meter-long, 100 mm-diameter Bentheimer and Boise sandstone samples using an advanced, high-pressure setup with medical X-Ray CT (XCT) imaging. Using novel beam-hardening and noise removal methods, we can resolve fluid distributions with a spatial resolution of 1.2 mm³ and temporal resolution of 90 s. The mobility (M) regime in each case is weakly unstable, M ≈ 0.5-5, with flow velocities equivalent to field scale injection rates. In the case of the weakly heterogeneous Bentheimer sample (porosity 0.26 ± 0.025), we find the plume migration is mainly controlled by buoyancy. On the other hand, the fluid distribution in the Boise sample is controlled by the strong unstructured heterogeneity (porosity 0.3 ± 0.1). The heterogeneity increases the gas trapping as less of the core is ultimately bypassed, and residual gas saturation increases behind local capillary barriers. We see little viscous instability in each experiment despite the unstable regime; structural heterogeneity and buoyancy largely control the flow under these field-relevant conditions. The meter scale 3D experimental dataset is provided open-access and represents an ideal benchmark to calibrate and improve multiphase flow models and upscaling methods.

我们对存在地质异质性的流动不稳定性（例如粘性、重力）的理解和建模受到缺乏在固结介质中相关尺度的实验观察的限制。通常，小样本尺寸（<50 mm 直径）限制了异质性的规模，并且不稳定手指的发展可能会受到样本边界的抑制。此外，缺乏 3D 动态数据，在一定程度上解决了观察手指生长和交互的问题。为此，我们使用先进的高压装置和医用 X 射线 CT (XCT ) 成像。使用新颖的光束硬化和噪声去除方法，³和 90 秒的时间分辨率。每种情况下的迁移率 ( M ) 状态都是弱不稳定的，M≈ 0.5-5，流速相当于现场规模的注入速率。在弱异质 Bentheimer 样品（孔隙度 0.26 ± 0.025）的情况下，我们发现羽流迁移主要受浮力控制。另一方面，博伊西样品中的流体分布受强烈的非结构化非均质性（孔隙率 0.3 ± 0.1）控制。由于最终绕过较少的岩心，非均质性增加了气体捕获，并且局部毛细管屏障后面的残余气体饱和度增加。尽管状态不稳定，但我们在每个实验中几乎没有看到粘性不稳定性；在这些与现场相关的条件下，结构异质性和浮力在很大程度上控制了流动。