Abstract: The migrating and enriching of fault gas during dynamic load-unload process are important indexes to evaluate the stress state and tectonic activity of underground medium. The Hutubi underground gas storage provides a natural experiment site for the analysis of the relationship between the gas geochemistry and the stress-strain status. In this paper, the soil gas concentrations of Rn, CO₂, Hg and H₂ during the gas injection in the Hutubi underground gas storage were analyzed. The results show that the soil gas contents and changing trend are close to the background value in the non-reservoir area and fault zone, which may reveal the weak activity of the fault. Significantly higher concentrations of soil gas H₂ and Hg are observed in the gas storage area, where H₂ maximum reaches 5.551×10^-4 and Hg maximum reaches 53ng/m³. Moreover, the abnormal soil gas H₂ and Hg measurement locations are more consistent. The variation trends of soil gas Hg, H₂, Rn, and CO₂may be related to the different gas generation and response mechanisms. The concentrations of soil gas H₂ and Hg are sensitive to the variation of pressure and the development of cracks in the underground gas storage, and they can reveal gas injection's effect on fault activity. This study provides a new basis for analyzing the influence of gas injection and withdrawal in Hutubi underground gas storage on fault activity.

Key words: soil gas, hydrogen, mercury, Hutubi underground gas storage, fault, seismic activity

摘要： 动力加卸载过程中的断层气体运移和富集特征，是评价地下介质受力状态和构造活动程度的重要指标之一。呼图壁地下储气库为研究气体地球化学变化特征与应力应变之间的关系提供了天然的实验场地。呼图壁地下储气库加压存储阶段，土壤气中Rn、CO₂、Hg和H₂浓度的观测结果表明，在非储气库区和断层处，土壤气浓度及变化趋势为背景值特征，可能揭示出断层的活动状态较弱。而在储气库区内观测到了土壤气中H₂和Hg浓度显著升高的现象，最大值分别为5.551×10^-4和53ng/m³，而且H₂和Hg浓度异常的测量位置较为一致。土壤气中Hg、H₂与Rn、CO₂的差异性变化趋势，可能与气体的产生机理和响应机制不同有关。土壤气中H₂和Hg的浓度可反映出地下储气库内的压力变化和裂隙通道，可揭示出储气库注气对断层活动性的影响程度。研究结果为分析呼图壁地下储气库注采气对断层活动性的影响提供了新的依据。

关键词: 土壤气, 氢气, 汞, 呼图壁地下储气库, 断层, 地震活动