Case study of geochemical reactions at the Nagaoka CO2 injection site, Japan

in this paper we present the results of an integrated field and experimental study on the geochernical reactions in a sandstone reservoir at Nagaoka, Japan, where the first Japanese pilot project Of C02 geological storage is underway. Prior to the C02 injection, we collected formation water and rock samples from the reservoir, and conducted laboratory experiments to investigate the geochemical reactions when injecting C02 into the reservoir. About 1 year after stopping the C02 injection, we again collected formation fluid using a Cased Hole Dynamics Tester (CHDT) at one of the three observation wells where C02 breakthrough was confirmed by time-lapse well logging. Chemical analyses of the POSt-CO2 injection samples indicate a high HC03- 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 C02-watey-rock reactivity. Our results demonstrated the potential Of C02 storage by formation water dissolution and mineral trapping Of C02. (c) 2008 Elsevier Ltd. All rights reserved.