Monitoring Subsurface CO2 Injection and Security of Storage Using Muon Tomography

The monitoring of carbon storage sites during CO2 injection and subsequent storage (to detect for possible leakage) is a major challenge. The methods available today, particularly those which can be applied to offshore sites are episodic and expensive. An elegant solution may be provided by cosmic-ray muon tomography, muons being the subatomic unstable particles produced from oxygen and nitrogen atoms, in the upper atmosphere in collision of protons and heavy nuclei accelerated in remnants of supernova explosions. Muon tomography has already been used to seek archaeological and geological features. We developed a model to test if this approach would work for monitoring CO2 storage and show that muon detection is a viable method. Our results indicate that we could detect as little as 0.4% change in the mean reservoir density at about 1 km depth (equivalent to 7% of pore volume). Hence, cosmic ray muon detection could monitor migration of injected CO2 continuously and inexpensively relative to seismic monitoring and help rapid introduction of this essential technology.