Monitoring of Fluid Injection in Longyearbyen CO2-Lab, Svalbard Using Microearthquakes

This study tempts to investigate the relationship between fluid injection and stress changes in a reservoir at the Longyearbyen CO2-Lab, Svalbard using microseismicity. It is a first step to verify the CO2 injectivity and storage abilities of the reservoir and turn Svalbard into a CO2 neutral community in the near future. We first use the continuous seismic data recorded at eight geophones near the injection well to automatically detect, phase-pick, and locate local earthquakes. Due to the complicated characteristics of the raw data, careful post-processing methods have to be followed to verify the automatically detected earthquakes from the first step. Then we will use those verified microearthquakes to study the migration pattern of the injected fluid and associated stress changes during and immediately after the injection period. In addition, we use a well-identified event, which occurred 17 hours after the water injection test, as a template and search similar events with low SNR using the matched filter method. We have found seven events with six of them occurred on the same day as the template. We will perform a comprehensive search of microearthquakes once we locate more template events.