Geophysical Monitoring on Controlled CO₂ Released Field Experiments: a Review Study = Geophysical Monitoring on Controlled CO₂ Released Field Experiments: a Review Study

다국어 초록 (Multilingual Abstract)

Geologically sequestrated carbon dioxide (CO₂) in deep subsurface can leak through leaky well or fault, thus the storage fails. Leaked CO₂ contaminates groundwater when reaching to the atmosphere. Many field experiments of releasing CO₂ into shallow depth in test bed sites, have been made not only to understand impacts of CO₂ in shallow groundwater or atmosphere but also to test monitoring methods for detecting the leaked CO₂. Among various monitoring methods, geophysical methods have been widely utilized to detect CO₂ plume migration in shallow depth before CO₂’s reaching to the atmosphere. This study reviews and analyzes geophysical monitoring experiments and results in seven existing field experiment sites. In several fields, geophysical measurements were carried out in time-lapse manners to monitor changes in physical properties of subsurface due to the presence of CO₂ before and during injection, while a couple of fields conducted CO₂ monitoring even after injection has been finished. After the analysis, this study not only summarizes changes in subsurface physical properties such as bulk electrical resistivity, complex resistivity and permittivity, but also analyzes effects of geological conditions on the changes in physical properties; whether the CO₂ injection zone is saturated or vadose zone, contains calcite minerals or clay, precipitation rate, etc. Further, this paper will also introduce tests of geophysical monitoring for shallow CO₂ injection experiment in Korea. This research was supported by KEITI (Project Number: 2018001810002), and partly by KETEP (No. 20194010201920).