Volume 66

Reactive Transport Modeling of Mineral Precipitation Induced by Geo-methanation Tianduoyi Wang, Keliu Wu, Qingyuan Zhu, Zhe Hu, Zhangxin Chen

Abstract

Methanation is one of the most common microbial reactions in underground hydrogen storage (UHS). This biogeochemical reaction induces biofilm growth and mineral dissolution/precipitation, which in turn alter the reservoir pore structure and permeability, affecting the long-term multi-cycle operation of UHS systems. However, quantitative studies on biomass variation, the formation mechanism, spatiotemporal evolution, and key controlling factors of mineral precipitation during the injection and storage stages of UHS systems remain scarce. Based on PHREEQC software, this study developed a Darcy-scale reactive transport model integrating microbial reaction kinetics and mineral precipitation kinetics, followed by model validation. The model was used to analyze the spatiotemporal evolution characteristics of porosity during the hydrogen injection stage and the characteristics of UHS system parameters during the storage stage. The results show that mineral precipitation exhibits a heterogeneous distribution during the injection stage, and porosity is mainly influenced by mineral precipitation. During the storage stage, hydrogen consumption reaches its maximum after approximately 4.5 months, and the subsequent UHS system attains a stable state. This study provides a quantitative prediction tool for mineral precipitation in UHS systems and geo-methanation processes, and offers critical technical support for the site selection and evaluation of related projects.

Keywords Underground hydrogen storage, Geo-methanation, Biofilm growth, Mineral precipitation, Reaction transport model