5:15 PM - 6:30 PM
[HSC05-P05] Development of a micro-seismic monitoring system for safety management at offshore CO2 geological storage site
Keywords:Geological CO2 storage, Traffic Light System, micro-seismicity, OBC
As various underground fluid injection projects, there are concerns that an increase of formation pressure induces earthquakes in geological CO2 storage. In enhanced geothermal systems (EGS) a protocol to manage the induced earthquakes had been proposed (Major et al., 2012). The system to manage large earthquakes by their operation with the monitoring of micro-seismicity is called Traffic Light System (TLS). Although earthquakes larger than the magnitude of 1.1 have not been reported at geological CO2 storage sites, we should deeply consider risk managements of induced earthquakes.
Our group has been developing a micro-seismicity management system for offshore CO2 geological storage, called Advanced TLS (ATLS). The requirements for the system are:(1) Capability to extract micro-seismic events ground motion data that include data of a natural earthquakes and high-level environmental noise by human activities, (2) Function to determine the hypocenters of micro-seismic events, and (3) Capability to process data in real time.
For the monitoring of seismicity at offshore site, Ocean Bottom Cable (OBC) is a powerful tool. It enables us not only real-time observation at far offshore seismometers, but also array data analyses. For the event pick from noisy data, we implemented Sequentially Discounting Auto-Regressive model learning (SDAR) and Adaptive Multiband Picking Algorithm (AMPA). We have examined this event picking method in real observation data, and confirmed that it works properly without time delay. After the event picking, the event information was evaluated using “hypomh” (Hirata and Matsuura, 1987). In parallel, a latest hypo-centre catalogue is collected from the Japan Methodological Agency (JMA), which is used to exclude natural earthquakes from the catalogue generated in ATLS.
The output of ATLS is the color of traffic light, representing safety level of the CO2 injection operates. The safety level is classified by several thresholds such as magnitude, hypocenter position, and frequency of earthquakes. These thresholds should be decided at each site. In addition to the main system, we have developed auxiliary tools to support seismic observation planning. The validation of ATLS and auxiliary tool have completed, and they are now ready to be applied to geological CO2 storage sites.
Our group has been developing a micro-seismicity management system for offshore CO2 geological storage, called Advanced TLS (ATLS). The requirements for the system are:(1) Capability to extract micro-seismic events ground motion data that include data of a natural earthquakes and high-level environmental noise by human activities, (2) Function to determine the hypocenters of micro-seismic events, and (3) Capability to process data in real time.
For the monitoring of seismicity at offshore site, Ocean Bottom Cable (OBC) is a powerful tool. It enables us not only real-time observation at far offshore seismometers, but also array data analyses. For the event pick from noisy data, we implemented Sequentially Discounting Auto-Regressive model learning (SDAR) and Adaptive Multiband Picking Algorithm (AMPA). We have examined this event picking method in real observation data, and confirmed that it works properly without time delay. After the event picking, the event information was evaluated using “hypomh” (Hirata and Matsuura, 1987). In parallel, a latest hypo-centre catalogue is collected from the Japan Methodological Agency (JMA), which is used to exclude natural earthquakes from the catalogue generated in ATLS.
The output of ATLS is the color of traffic light, representing safety level of the CO2 injection operates. The safety level is classified by several thresholds such as magnitude, hypocenter position, and frequency of earthquakes. These thresholds should be decided at each site. In addition to the main system, we have developed auxiliary tools to support seismic observation planning. The validation of ATLS and auxiliary tool have completed, and they are now ready to be applied to geological CO2 storage sites.