Boon Maartje, Rademaker Tim, Winardhi Chandra Widyananda, Hajibeygi Hadi
Institute of Applied Mechanics, University of Stuttgart, 70569, Stuttgart, Germany.
Faculty of Civil Engineering and Geosciences, Delft University of Technology, 2600 GA, Delft, The Netherlands.
Sci Rep. 2024 Dec 4;14(1):30170. doi: 10.1038/s41598-024-81720-4.
To safely and efficiently utilize porous reservoirs for underground hydrogen storage (UHS), it is essential to characterize hydrogen transport properties at multiple scales. In this study, hydrogen/brine multiphase flow at 50 bar and 25 °C in a 17 cm Berea sandstone rock core was characterized and visualized at the pore and core scales using micro X-ray CT. The experiment included a single drainage and imbibition cycle during which relative permeability hysteresis was measured, and two no-flow periods to study the redistribution of hydrogen in the pore space during storage periods. An end-point relative permeability of 0.043 was found at [Formula: see text], and the residual gas saturation was measured to be 0.32. Despite extensive pre-equilibration, significant dissolution of hydrogen into brine occurred near the core inlet due to elevated pressures and the corresponding increase in hydrogen solubility. During drainage, many disconnected hydrogen ganglia were observed further down the core which could be explained by the exsolution of the dissolved hydrogen. During imbibition, the dissolution of hydrogen led to the formation of preferential flow paths near the inlet, and eventually removed most of the trapped hydrogen in the final stage of the experiment. The two no-flow periods were characterized by the fragmentation of medium-sized hydrogen ganglia and the growth of a few larger ganglia, providing evidence for hydrogen re-connection through the dissolution-driven process of Ostwald ripening. These results demonstrate that despite the low solubility of hydrogen in brine, hydrogen dissolution can significantly influence the observed multiphase flow and trapping behavior in the reservoir and should be considered in UHS modeling.
为了安全、高效地利用多孔储层进行地下氢存储（UHS），在多个尺度上表征氢传输特性至关重要。在本研究中，使用微型X射线计算机断层扫描（micro X-ray CT）在孔隙和岩心尺度上对17厘米长的贝雷砂岩岩心中50巴和25℃下的氢/盐水多相流进行了表征和可视化。实验包括一个单一的排水和吸水循环，在此期间测量了相对渗透率滞后，以及两个无流动期，以研究存储期间孔隙空间中氢的重新分布。在[公式：见原文]时发现端点相对渗透率为0.043，残余气饱和度测量值为0.32。尽管进行了广泛的预平衡，但由于压力升高以及氢溶解度相应增加，在岩心入口附近仍发生了大量氢溶解于盐水的现象。在排水过程中，在岩心更下游观察到许多不连续的氢气泡，这可以用溶解氢的析出解释。在吸水过程中，氢的溶解导致入口附近形成优先流动路径，并最终在实验的最后阶段去除了大部分被困氢。两个无流动期的特征是中等大小的氢气泡破碎以及少数较大气泡的生长，这为通过奥斯特瓦尔德熟化的溶解驱动过程实现氢重新连接提供了证据。这些结果表明，尽管氢在盐水中的溶解度较低，但氢溶解会显著影响储层中观察到的多相流和捕集行为，在UHS建模中应予以考虑。
