CO2 injection in the subsurface is characterized by intermittent behavior during the well start-up, shut-in, due to fluctuations in CO2 supply, or due to undesired events. Such cases might be accompanied by phase changes, which are associated with temperature changes. The associated thermal stresses can lead to severe problems because the sealing ability of well barriers such as steel, casing, cement, and rock formation can be compromised.
The commercial solutions for assessing thermal stresses in the near-wellbore region utilize coupling of wellbore flow and geomechanical simulators. However, running such models is computationally expensive and is not well suited for calibration using monitoring data. Besides, a large amount of data is required to set up the models, which is often not available.
The project will tailor a numerical simulation model for single- and multiphase mixtures of CO2 and CO2-rich mixtures in realistic well configurations, including friction and heat transfer. In order to account for the induced thermal stresses in the cement and in the reservoir, an approximate model for the near-wellbore stresses distribution will be developed and coupled to the wellbore flow model. This will allow exploring the operational conditions that minimize the risks (e.g., leakage and wellbore stability) associated with the induced thermal stresses. The developed simulation tool will be applied for a planned CO2 injection well at the Stenlille gas storage site, operated by Gas Storage Denmark.
- Construct a realistic coupled model at the well-scale.
- Preliminary analysis of high-level risks associated with the induced thermal stresses.
- Identify the safe operating envelope for the conditions of a selected Stenlille well.