Overview
Reliable seismic monitoring provides information on the location and size of events and is essential for ensuring the safety and integrity of offshore CO₂ storage. In the North Sea, this presents specific challenges: storage sites are located offshore, existing public monitoring networks are located onshore, non-public offshore monitoring networks are unevenly distributed, and environmental noise can limit data quality.
SAFE-C addresses these challenges by developing and integrating advanced monitoring technologies tailored to offshore conditions, combining established approaches with emerging solutions.
Monitoring Challenges in the North Sea
Seismic monitoring in the North Sea must account for several constraints:
- Limited sensor coverage of offshore areas compared to onshore
- Possibly large distances between monitoring stations and storage sites
- High levels of environmental and industrial noise
- Variability in data availability and accessibility across countries
These factors can lead to reduced detectability of small seismic events and increased uncertainty in their location and interpretation.
Sensor Technologies
SAFE-C evaluates and combines multiple sensing technologies to improve monitoring performance:
- Onshore seismic networks
Existing national networks provide continuous regional coverage and form the backbone for detecting larger events. - Ocean-bottom sensors
Seafloor instruments allow monitoring closer to offshore storage sites, improving detection thresholds and location accuracy. - Distributed Acoustic Sensing (DAS)
Fibre-optic cables are used as dense arrays of sensors, enabling high-resolution measurements over large distances. - Posthole seismometers
A novel sensor concept developed for North Sea conditions, designed to provide stable, real-time seismic data from shallow offshore installations. Learn more on posthole seismometers
Integrated Monitoring Systems
A key objective of SAFE-C is to integrate these technologies into a coherent monitoring system. This includes:
- Combining onshore and offshore data streams
- Evaluating the performance of different sensor configurations
- Assessing data quality and completeness in near real time
- Identifying gaps in current monitoring coverage
By integrating multiple data sources, the project improves both the detection capability and the reliability of seismic observations.
Network Design and Performance
SAFE-C develops tools to assess and optimise monitoring networks, including:
- Detection capability and magnitude thresholds
- Location accuracy and uncertainty
- Cost-benefit analysis of different sensor deployments
These analyses support the design of efficient monitoring strategies tailored to specific storage sites and regional conditions.
Case Studies
The monitoring technologies and strategies developed in SAFE-C are tested and validated at selected CO₂ storage sites in the North Sea.
Learn more about our case study sites