Impact of cement composition, brine concentration, diffusion rate, reaction rate and boundary condition on self-sealing predictions for cement-CO 2 systems

Journal Article · 19 April 2024 · International Journal of Greenhouse Gas Control

DOI: https://doi.org/10.1016/j.ijggc.2024.104126 · OSTI ID:2375941

Iyer, Jaisree  ^[1]; Smith, Megan M.  ^[1]

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1. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Geological CO₂ storage (GCS) plays an important role in curbing CO₂ emissions by reducing the carbon footprint of difficult to decarbonize operations and achieve negative CO₂ emissions through activities like Bioenergy with Carbon Capture and Storage (BECCS) and Direct Air Carbon Capture and Storage (DACCS). Leakage of CO₂ through wells is an important concern when it comes to deployment of large-scale GCS. Existing wells in sites that are otherwise suitable for GCS can act as conduits for stored CO₂ to escape the reservoir. There is broad consensus that the main risk of leakage through wellbores is via fractures/damaged pathways. The results from several studies evaluating the permeability evolution of cement fractures in wells upon leakage of CO₂ agree that smaller fracture apertures, slower brine velocities and higher brine residence times promote self-sealing of fractures by mineral precipitation. Quantitatively, however, the differences in sealing conditions are significant and are typically attributed to differences in experimental conditions or model assumptions. Here we examine the sensitivity of our model, describing CO₂ leakage through wellbores, to cement composition, brine concentration, diffusion rates, and reaction rates. We also evaluate the impact of the boundary condition to allow comparisons between observations from experiments performed at constant flow rate and model predictions made at constant pressure conditions. Our results show that diffusion and reactions rates have the most impact on the self-sealing criteria for cement-CO₂ systems. In addition, conditions associated with self-sealing of fractures at constant flow rate require longer fractures, smaller fracture apertures, and slower velocities than under constant pressure.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); USDOE Office of Fossil Energy and Carbon Management (FECM), Office of Carbon Management
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 2375941
• Report Number(s): LLNL--JRNL-855175; 1084066
• Journal Information: International Journal of Greenhouse Gas Control, Journal Name: International Journal of Greenhouse Gas Control Vol. 134; ISSN 1750-5836
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English