Influence of carbon dioxide on underground gas storage

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This literature study surveys the effect of CO2 in underground gas storage, particularly in light of increasing renewable energy sources. As biogas usage rises, CO2 levels are expected to exceed the current natural gas concentration of less than 1%, potentially reaching the EASEE-gas-standard value of 2.5% in the German gas grid. This study investigates the implications of such changes, noting that no effects on underground storage for natural gas with similar CO2 concentrations have been documented. The analysis includes extreme cases involving sour gas (CO2 + H2S), enhanced oil recovery (100% CO2), carbon capture and storage technology (100% CO2), and town gas storage (CO2, CO, H2, O2). The findings suggest that an increase in CO2 content up to 2.5% does not negatively impact the integrity and reservoir properties of storage facilities, which are designed to accommodate this concentration. However, a rise to 4% due to biogas processing is not well-documented, and any increase in CO2 may lead to increased corrosion in wellbores and surface facilities, necessitating corrosion control measures. The interactions between reservoir materials and biogas components remain uncertain, and the transferability of experiences from French underground gas storage regarding CO2 and H2S concentrations is not confirmed. Further investigation is needed to clarify the mechanisms at play and assess risks for German underground gas storage relate