Dispersion coefficients are determined, and entry/exit effects during gas displacement experiments in porous media are characterized. Two methods are proposed for measuring concentration breakthrough profiles: using an X-ray scanner for internal core measurements and a Raman spectrometer for postcore measurements. The experimental setup includes a coreflooding system with X-ray scanning capabilities and a high-pressure Raman probe. A description of the data processing of X-ray and Raman signals to derive concentration profiles and calculate mixing coefficients is presented. Results from the experiments are discussed, including mixing coefficients for CO₂ displacing CH₄ and CH₄ displacing CO₂, and their variations with pressure, temperature, and flow velocity. Dispersion coefficients are found to be higher with CH₄ as the displacing fluid compared to CO₂, suggesting higher mixing during gas injection in underground gas storage with a CO₂ cushion. The study extends the analysis to the structure promising for underground storage in Poland, analyzing dispersion coefficients and other parameters for gas injection and production scenarios. The proposed methods show promise for characterizing mixing processes and optimizing UGS operations, with potential applications in studying other gases such as higher hydrocarbons or H₂ for future energy developments.

中文翻译：

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地下天然气储存岩心中二氧化碳/甲烷混合过程分析


确定分散系数，并表征多孔介质中气体驱替实验期间的进入/退出效应。提出了两种测量浓度突破分布的方法：使用 X 射线扫描仪进行内部岩心测量，使用拉曼光谱仪进行岩心后测量。实验装置包括具有 X 射线扫描功能的岩心驱替系统和高压拉曼探头。描述了 X 射线和拉曼信号的数据处理，以得出浓度分布并计算混合系数。讨论了实验结果，包括 CO ₂ 置换 CH ₄ 和 CH ₄ 置换 CO ₂ 的混合系数及其变化与压力、温度和流速。研究发现，与 CO ₂ 相比，以 CH ₄ 作为驱替液的分散系数更高，这表明在使用 CO ₂ 坐垫。该研究将分析扩展到波兰有望用于地下储存的结构，分析气体注入和生产场景的分散系数和其他参数。所提出的方法显示出表征混合过程和优化 UGS 操作的前景，并在研究其他气体（例如高级碳氢化合物或 H ₂ ）以用于未来能源开发方面具有潜在应用。