Investigations of CO2 flow and transport processes in high pressure gas injections (100 bar) using micro-computer tomography, representative micro-models and numerical models

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Underground CO2-gas storage (CCS) is an important option for a climate-friendly energy policy. On the other hand, energy security must be guaranteed through "enhanced" oil production (EOR) using CO2 gas injection. Within the framework of the research project, important CO2-flow- and transport processes are investigated during high-pressure gas injections (100 bar) using µ-Computer Tomography (CT) and representative micromodels. For this purpose, a high-pressure measuring station (up to 100 bar) will be set up for both column and micro-model experiments. The main objective is to verify the results of previous μ-CT- and micromodel studies on the influence of wettability and surface roughness on multiphase flow patterns under high-pressure conditions and to discover new pressure-dependent phenomena. CO2, water and oil are used as fluids and glass beads sediments, fine sands and sandstones as porous media. The wettability is controlled by means of silanization or suitable fluid-fluid pairs. Of fundamental interest are the questions, whether percolation can describe the multiphase flow behavior and universal scaling the cluster size distribution and what influence, pore structure, microstructure of the solid surface and heterogeneous wettability have on the flow pattern and the trapping process. To understand the gas formation processes, it is important to compare pressure-dependent CO2 transport (diffusion, mass transfer) in homogeneous and heterogeneous thermodynamic systems. Porous media saturated with water or oil are used as heterogeneous systems. Methodologically, the pore structure and pore space topology are analyzed and quantified by means of µ-CT and image analysis, and the geometry and static distribution of trapped fluid clusters by means of cluster analysis. The dynamics of the trapping process are investigated using optical visualization with a high-resolution SLR camera or fluorescence microscopy of representative 2D-Si-micromodels with controlled wall roughness. The expected results are of fundamental interest as well as of great practical relevance, as they improve the understanding of the pore scale processes and thus contribute to CCS and EOR.