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ABSTRACT: Wellbore integrity is critical to the long-term security of CO2 geological storage. During CO2 injection, the significant temperature difference between the injected CO2 and formation at depth will stress the near wellbore region, potentially leading to generation of leakage pathways. In this work, we perform a numerical study to investigate the role of CO2 injection temperature and pressure based on a 3D coupled thermal-hydro-mechanical model of the formation-cement-casing system. The study takes advantage of the publically available dataset of the Northern Lights project. We present a multistage finite element model that considers the sequential changes of stress and displacement during each stage of the CO2 injector life, such as drilling, casing, cementing, completion, and injection. We simulate a cyclic thermal loading and the results show that no debonding occurs at cement-casing or cement-formation interface during cooling and heating phases, which indicates that the high in-situ effective horizontal stresses tend to mitigate the negative impacts of thermal stresses on wellbore integrity. We also study the impact of several key factors such as the cement elastic moduli and thermal properties. The numerical model offers a solution to quantify the potential thermal-mechanical impact across the entire lifecycle of CO2 injector. 1. INTRODUCTION Carbon capture, utilization and storage (CCUS) is a critical technology to remove the massive amount of CO2 from the atmosphere and mitigate global warming (Bachu, 2008; Benson Pacala Rutqvist et al., 2012; Sun et al., 2023, 2022). It is crucial to prevent leakage from wellbores to establish long-term CO2 storage (Bachu Wigand et al., 2009).
Sun et al. (Sun,) studied this question.