Trapping mechanisms in field scale: Results from Nagaoka geologic CO2 storage site

The importance of capillary and solubility trappings has been reported, since they contribute the integrity of CO2 sequestration from the early stage of CO2 storage. This paper reports contribution of these trappings in field scale derived from the logging data at the Nagaoak site. At this site, loggings for the monitoring purpose have been conducted for more than 12 years and about 11 years during the post-injection period. From the neutron logging CO2 saturation was evaluated, and the negative anomaly in the induction logging accounted for the solubility trapping. The relationship between the maximum and the latest CO2 saturation was used to investigate the initial-residual (IR) curve at the site. The IR curve obtained from the down-dip position showed that a Land's model could explain the hysteretic flow properties. These results among the observation wells could be used to interpret the migration of CO2 in the reservoir. The results from induction logging indicated that solubility trapping was progressing as diffusion process. These results could be used for the calibration of two-phase flow models for the long-term behavior of CO2 in geological storage site. (C) 2017 The Authors. Published by Elsevier Ltd.