During the flow of a matrix-dissolving fluid through porous media, positive feedback between flow and reaction can create various, time-evolving forms. These forms exhibit a range of geometries, from complex, cave-like structures (wormholes) to simple frontal dissolution. This complex example of hydrodynamic instability is sensitive not only to flow parameters but also to the spatial properties of the porous media. While the effects of flow rate and reaction rate on the morphologies of wormholes are now understood, the mechanisms governing their propagation dynamics remain significantly less characterized.
Our work is focused on the fast-progressing dominant wormhole regime, which is relevant in a range of industrial and natural cases, including carbon capture and storage (CCS). To understand the dynamics of fluid interaction with the surrounding porous matrix, high temporal and spatial resolution data are required, both in experimental and numerical studies. On experimental side, we leveraged the capabilities of the ID-19 beamline at the European Synchrotron Radiation Facility (ESRF), to conduct a series of experiments that aimed to capture 4D X-ray computed tomography (X-CT) high-resolution images of developing wormholes under different flow conditions. Such datasets allowed for the evaluation of a wide range of geometrical properties, which could be correlated with both numerical and analytical studies. The numerical work utilized resources of ICM UW and LUMI supercomputer in an attempt to recover experimental results in simulations based on CT data. In both approaches we focus on how the dynamics of the instability that grows in natural, highly heterogeneous rock relate to an analytical model of a tube growth and the onset of the instability.
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