The industry partners of the Northern Lights full-scale CCS project and CGG, together with researchers at NORSAR and the Univeristy of Bergen, are working on developing and demonstrating cost effective monitoring of seismicity. HNET3 is the current project phase, leading up to planned start of injection in 2024.
HNET3 is building on earlier project phases. These projects also build on many other CLIMIT projects. Below you can read more about previous phases.
HNET Phase 1
Phase 1, called Smeaheia Natural Seismicity Network (SNS-Net), ran from August 2018 to July 2019 and was set up to design and verify the plans for the operational phases.
SNS-Net was dedicated to accelerating monitoring solutions for the first full-chain offshore CO2 storage project. The main objective was to investigate solutions for seismic instrumentation that are sufficient and cost-effective to establish the necessary background seismic level in the Smeaheia area.
SNS-Net was also a CLIMIT Demo project, led by NORSAR and was co-funded by Equinor and Gassnova.
HNET Phase 2
Phase 2, called Demonstration of optimized basline seismicmonitoring network for the Horda platform (H-Net project) , was focused on development, demonstration and optimization of a Natural Seismicity Network for the wider Horda Platform region, which includes the Northern Lights Aurora CO2 injection site.
Phase 2 was executed jointly by Equinor and NORSAR, with Shell and Total acting in a technical advisory role, and was co-financed by Gassnova and Equinor.
Phase 2 started in September 2019 and ended in January 2021.
Summary of the main outcomes of the HNET Phase 2 project
- Deployment and testing of a new enhanced onshore seismic monitoring array, called HNAR, and located at Holsnøy north of Bergen.
- Using this array, we were able to demonstrate several improvements that could be achieved with a dedicated seismic event detection array, including significantly improved event detection and improved accuracy in determining the location of events.
- We also evaluated optimal use of selected geophones from offshore permanent reservoir monitoring arrays (PRM systems) and showed how in combination with onshore detection systems we can further improved event location accuracy.
- Furthermore, by analyzing event data from the offshore geophones at the Grane field we were able to show how offshore arrays could function in terms of detection of natural seismicity as a function of distance.
- Statistics of natural seismicity for the Horda platform area, using the entire Norwegian seismic catalogue, were also assessed to determine earthquake likelihoods and current detection thresholds.
- The overall Magnitude of completeness (Mc) for this region was found to be 1.4 and the slope of the earthquake frequency plot (the b-value) was found to be close to 1, suggesting a dominantly tectonic character for seismicity in this region.
- Using these technical assessments along with the observations from the new HNAR array, we were able to gain new insights into the natural seismicity in this area as a contribution to background seismicity monitoring prior to start of CO2 injection at the Northern Lights (Aurora) site.
The Phase 2 HNET report can be downloaded here.