Developing DAS Technology for CCS Monitoring and Subsurface Properties Assessment using Underground and Submarine Dark-fiber

Summary The long-term monitoring of Carbon Capture and Storage (CCS) sites requires scalable, high-resolution sensing to ensure CO2 stability and detect leakage. Distributed Acoustic Sensing (DAS) with underground and submarine dark-fiber networks offers a cost-effective solution for seismic and environmental monitoring. Field experiments across South Korea validated DAS for CCS applications. In Pyeongtaek, a 35 km dark-fiber segment detected seismic signals, confirming strong performance in the mid-frequency range (≥3 Hz). Controlled-source tests further demonstrated its ability to capture high-frequency seismic signals (≤150 Hz). In Daejeon, back-tracking methods reconstructed fiber paths, enhancing geospatial referencing for CCS monitoring. Additionally, DAS applications extended to traffic monitoring in Gyeongju and tunnel detection in Paju, highlighting its broader potential. DAS-equipped dark-fiber networks provide a scalable and cost-effective alternative for CCS and geophysical monitoring. Future research will enhance real-time data processing and expand applications to submarine and underutilized optical fiber networks