Abstract Case study of geochemical reactions at the Nagaoka CO2 injection site, Japan.
International Journal of Greenhouse Gas Control, 2, 309-318, 2008.
Mito Saeko, Xue Ziqiu, Ohsumi Takashi

In this paper we present the results of an integrated field and experimental study on the geochemical reactions in a sandstone reservoir at Nagaoka, Japan, where the first Japanese pilot project of CO2 geological storage is underway. Prior to the CO2 injection, we collected formation water and rock samples from the reservoir, and conducted laboratory experiments to investigate the geochemical reactions when injecting CO2 into the reservoir. About 1 year after stopping the CO2 injection, we again collected formation fluid using a Cased Hole Dynamics Tester (CHDT) at one of the three observation wells where CO2 breakthrough was confirmed by time-lapse well logging. Chemical analyses of the post-CO2 injection samples indicate a high HCO3- concentration compared to original formation water. Concentrations of Ca, Mg, Fe, Mn and Si also increased. The field results were quite similar to the laboratory experiments on CO2?water?rock reactivity. Our results demonstrated the potential of CO2 storage by formation water dissolution and mineral trapping of CO2.

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