This paper focuses on the modeling of hydrogen (H2) storage in subsurface formations, particularly focusing on the equilibrium between H2 and brine and its implications for hydrogen transport properties in black-oil reservoir simulations. Initially, we evaluate and calibrate various equations of state (EoS) for H2-water and H2-brine mixtures. Our analysis ranges from the molecular-level Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equation to a more explicit version of the Redlich–Kwong cubic EoS, and concludes with an empirical Henry–Setschenow (HS) model. These models are compared in terms of their ability to predict mutual solubilities with validation against experimental data. This study compares the strengths and limitations of each thermodynamic model, highlighting their overall good predictability across various temperatures, pressures, and salinity levels with a relatively moderate number of adjustable parameters. Subsequently, we apply these thermodynamic models to generate Pressure–Volume–Temperature (PVT) phase equilibrium data for use in black-oil simulations, focusing on the behavior of H2 in saline aquifers. Our investigation examines the effects of salt concentration, H2 solubility, molecular diffusion, and the impact of cycling frequency, injection and withdrawal rates on the storage and recoverability process. We present three numerical examples to illustrate these concepts: a 2D aquifer model, a modified benchmark originally designed for simulating the conversion of natural gas to hydrogen storage, and a 3D anticlinal dome-shaped aquifer model. These examples cover a range of complexities, such as heterogeneous permeability, porosity variations, and diverse rock types with specific entry pressures, providing a comprehensive overview of the factors influencing H2 storage in subsurface formations.

中文翻译：

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咸水层储氢的相行为和黑油模拟


本文重点关注地下地层中氢 (H2) 储存的建模，特别关注 H2 和盐水之间的平衡及其对黑油储层模拟中氢传输特性的影响。最初，我们评估和校准氢气-水和氢气-盐水混合物的各种状态方程（EoS）。我们的分析范围从分子水平的扰动链统计关联流体理论 (PC-SAFT) 方程到更明确版本的 Redlich-Kwong 立方 EoS，并以经验性的 Henry-Setschenow (HS) 模型作为结论。对这些模型预测互溶性的能力进行了比较，并根据实验数据进行了验证。这项研究比较了每种热力学模型的优点和局限性，强调了它们在各种温度、压力和盐度水平上的总体良好可预测性，以及相对适中的可调节参数。随后，我们应用这些热力学模型生成压力-体积-温度 (PVT) 相平衡数据，用于黑油模拟，重点关注盐水含水层中氢气的行为。我们的研究考察了盐浓度、氢气溶解度、分子扩散的影响，以及循环频率、注入和提取速率对储存和可恢复过程的影响。我们提出了三个数值示例来说明这些概念：2D 含水层模型、最初设计用于模拟天然气向储氢转化的修改基准，以及 3D 背斜圆顶形含水层模型。 这些例子涵盖了一系列复杂性，例如非均质渗透率、孔隙度变化以及具有特定入口压力的不同岩石类型，全面概述了影响地下地层中氢气储存的因素。