TY - JOUR

T1 - Thermoporoelastic model for fluid-driven debonding of cement during CO2 injection in a vertical well

AU - Valov, A. V.

AU - Dontsov, E. V.

AU - Zhang, Fengshou

N1 - A.V. Valov acknowledges the financial support of the Russian Federation represented by the Ministry of Science and Higher Education (grant No. 075-15-2023-588). F. Zhang acknowledges the support provided by the National Key Research and Development Project (grant No. 2023YFE0110900).

PY - 2026/3

Y1 - 2026/3

N2 - Well integrity is a critical challenge in carbon capture and storage (CCS) projects, where debonding of cement sheath can form preferential pathways for CO2 leakage. This study introduces a numerical framework for simulating fluid-driven debonding along the cement interfaces during CO2 injection. A pseudo-3D fracture propagation model, adapted to cylindrical well geometry, is coupled with a thermoporoelastic finite element mechanical model of the composite casing-cement-formation system. The framework accounts for poroelastic material behavior, thermal stresses, variations in fluid pressure and temperature, in-situ stress anisotropy, formation layering, and initial stress states induced by well construction and cement hydration. Fracture propagation is simulated in both vertical and circumferential directions, incorporating the effects of buoyancy, fluid viscosity, interfacial adhesion strength, and pressure-dependent leak-off. Numerical results reveal three distinct debonding regimes: crescent-shaped partial debonding, large incomplete debonding with non-monotonic aperture, and complete debonding that is characterized by a fully open channel around the circumference of the well. Sensitivity analysis reveals that debonding evolution is strongly influenced by cement shrinkage, injection conditions, cold fluid effects, and changes in reservoir stress over time. The model provides a predictive tool for assessing leakage risk and fracture evolution under varying cementing conditions, injection scenarios, and reservoir stress states.

AB - Well integrity is a critical challenge in carbon capture and storage (CCS) projects, where debonding of cement sheath can form preferential pathways for CO2 leakage. This study introduces a numerical framework for simulating fluid-driven debonding along the cement interfaces during CO2 injection. A pseudo-3D fracture propagation model, adapted to cylindrical well geometry, is coupled with a thermoporoelastic finite element mechanical model of the composite casing-cement-formation system. The framework accounts for poroelastic material behavior, thermal stresses, variations in fluid pressure and temperature, in-situ stress anisotropy, formation layering, and initial stress states induced by well construction and cement hydration. Fracture propagation is simulated in both vertical and circumferential directions, incorporating the effects of buoyancy, fluid viscosity, interfacial adhesion strength, and pressure-dependent leak-off. Numerical results reveal three distinct debonding regimes: crescent-shaped partial debonding, large incomplete debonding with non-monotonic aperture, and complete debonding that is characterized by a fully open channel around the circumference of the well. Sensitivity analysis reveals that debonding evolution is strongly influenced by cement shrinkage, injection conditions, cold fluid effects, and changes in reservoir stress over time. The model provides a predictive tool for assessing leakage risk and fracture evolution under varying cementing conditions, injection scenarios, and reservoir stress states.

KW - CO2 injection

KW - Interface debonding

KW - Well integrity

UR - https://www.scopus.com/pages/publications/105026696963

UR - https://www.mendeley.com/catalogue/29697332-4ec2-33ec-bc07-3e7190dddb19/

U2 - 10.1016/j.gete.2025.100785

DO - 10.1016/j.gete.2025.100785

M3 - Article

VL - 45

JO - Geomechanics for Energy and the Environment

JF - Geomechanics for Energy and the Environment

SN - 2352-3808

M1 - 100785

ER -