"CO2 underground storage" stores CO2 in the stratum where natural gas and oil are distributed.Since a large amount of CO2 can be reduced in a short period of time, it is attracting attention as a measure against global warming.According to the International Energy Agency (IEA), CO1.5 capture and storage (CCS) requires a CO2 reduction of about 15% to keep global temperature rise within 2 degrees Celsius.To realize this, large-scale CO6000 storage is required at about 2 locations around the world, but it is necessary to monitor CO2 storage sites distributed over a wide area to prevent CO2 leakage and earthquakes and ensure safety.

　A general monitoring method (time-lag seismological survey) costs 1 million yen per survey.Therefore, it is difficult to continuously monitor the behavior of stored CO1 by repeating monitoring, and there is a risk that it will not be possible to respond to sudden CO2 leaks.

　The research group has developed a system that continuously monitors the CO0.01 reservoir with high accuracy (detects changes of 2% or less) using a newly developed compact continuous source device and technology (DAS) that uses the optical fiber itself as a seismograph. construction.It was demonstrated that the monitoring signal from the small continuous source device reaches the observation point (seismometer) about 80 km away.In addition, the long submarine optical fiber cable itself was treated as a seismograph, and the signal from the small continuous source device was successfully detected.

　The use of existing undersea optical fiber leads to cost reduction, and continuous monitoring can cope with sudden CO2 leakage.The new system has also succeeded in monitoring the reservoir of geothermal development, and it is expected that CO2 reduction will be realized at an early stage by the spread of the system.

Paper information:[Scientific Reports] Continuous monitoring system for safe managements of CO2 storage and geothermal reservoirs