Carbon Capture and Storage (CCS) and geothermal energy production are now extensively developed industries contributing to sustainable energy production. Both CCS and geothermal industries operate wells drilled in the subsurface and used to inject fluids (CO2 or water) and, in some cases, to produce injected fluids back such as at water circulation in geothermal energy production.
Energy- and cost-efficiency as well as safety and conformance of well operations are the main challenges faced now in the industries mentioned above. This PhD study focuses on finding new solutions to address these challenges through development of efficient well monitoring technologies based on capabilities of modern sensing systems, e.g. permanent downhole gauges providing cost- and energy-efficient pressure and temperature monitoring in the wells. Leakage of injected fluids from wellbore and target geological formation chosen for injection or storage is one of the conformance issues addressed in this study. Combination of physical models, results of laboratory experiments with machine learning methods and interpretation of well pressure and temperature measurements is used to solve this and other issues occurring during injection operations. Monitoring of wells after injection operations is also in the focus in the context of long-term CO2 storage in geological formations. The study contributes to development of new sustainable solutions for CO2 storage & geothermal wells facilitating progress in these emerging industries.