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Fully Coupled Thermo-hydro-mechanical Model for Wellbore Stability Analysis in Deep Gas-Bearing Unsaturated Formations Based on Thermodynamics
https://orcid.org/http://orcid.org/0000-0002-8754-9156
A fully rigorous unsaturated thermo-hydro-mechanical (THM) coupling model based on non-equilibrium thermodynamics and continuum mechanics is developed to investigate the instability mechanism of the borehole drilled in deep gas-bearing formations. It incorporates the gas–water two-phase seepage phenomena, geomechanical loading, and temperature-difference disturbance during deep drilling process. Comparing the predictions of the previous saturated THM model and the presented model, the maximum relative errors of pore pressure, effective radial stress, effective tangential stress, and temperature are 30.2%, 34.6%, 3.4%, and 0.5%, respectively. The maximum prediction deviation in the width and depth of the failure zone occurs at the early time (t = 10−5 d). The unsaturated thermal coupling effect, although less influential on pore pressure and effective radial stress, makes a great contribution to the effective tangential stress with a maximum relative error of 10.1% for the temperature-difference of 30 K, and enhances the time dependence of the failure zone. The cooling condition is favorable to avoid shear collapse failure of the borehole, while the heating condition is not. The results also show that the gas-bearing formations with lower initial water saturation, higher rock permeability, or higher water phase relative permeability correspond to the higher risk of wellbore instability. The thermal conductivity and thermal expansion coefficient of the solid phase have a much greater effect on wellbore stability than those of the fluid phases. The effect of unsaturated THM coupling on wellbore stability may be more significant at lower rock permeabilities. The research findings provide insight into the wellbore stability analysis during drilling in deep gas-bearing formations.
A fully rigorous unsaturated thermo-hydro-mechanical (THM) coupling model based on thermodynamics is developed.
The unsaturated THM responses of pore pressure, stress components, and failure zone of a borehole were clarified.
The prediction differences between the presented model and previous saturated THM and unsaturated HM models were quantitatively analyzed.
The influence of two-phase seepage and thermal transport on wellbore stability were discussed parametrically.
Fully Coupled Thermo-hydro-mechanical Model for Wellbore Stability Analysis in Deep Gas-Bearing Unsaturated Formations Based on Thermodynamics
https://orcid.org/http://orcid.org/0000-0002-8754-9156
A fully rigorous unsaturated thermo-hydro-mechanical (THM) coupling model based on non-equilibrium thermodynamics and continuum mechanics is developed to investigate the instability mechanism of the borehole drilled in deep gas-bearing formations. It incorporates the gas–water two-phase seepage phenomena, geomechanical loading, and temperature-difference disturbance during deep drilling process. Comparing the predictions of the previous saturated THM model and the presented model, the maximum relative errors of pore pressure, effective radial stress, effective tangential stress, and temperature are 30.2%, 34.6%, 3.4%, and 0.5%, respectively. The maximum prediction deviation in the width and depth of the failure zone occurs at the early time (t = 10−5 d). The unsaturated thermal coupling effect, although less influential on pore pressure and effective radial stress, makes a great contribution to the effective tangential stress with a maximum relative error of 10.1% for the temperature-difference of 30 K, and enhances the time dependence of the failure zone. The cooling condition is favorable to avoid shear collapse failure of the borehole, while the heating condition is not. The results also show that the gas-bearing formations with lower initial water saturation, higher rock permeability, or higher water phase relative permeability correspond to the higher risk of wellbore instability. The thermal conductivity and thermal expansion coefficient of the solid phase have a much greater effect on wellbore stability than those of the fluid phases. The effect of unsaturated THM coupling on wellbore stability may be more significant at lower rock permeabilities. The research findings provide insight into the wellbore stability analysis during drilling in deep gas-bearing formations.
A fully rigorous unsaturated thermo-hydro-mechanical (THM) coupling model based on thermodynamics is developed.
The unsaturated THM responses of pore pressure, stress components, and failure zone of a borehole were clarified.
The prediction differences between the presented model and previous saturated THM and unsaturated HM models were quantitatively analyzed.
The influence of two-phase seepage and thermal transport on wellbore stability were discussed parametrically.
Fully Coupled Thermo-hydro-mechanical Model for Wellbore Stability Analysis in Deep Gas-Bearing Unsaturated Formations Based on Thermodynamics
https://orcid.org/http://orcid.org/0000-0002-8754-9156
A fully rigorous unsaturated thermo-hydro-mechanical (THM) coupling model based on non-equilibrium thermodynamics and continuum mechanics is developed to investigate the instability mechanism of the borehole drilled in deep gas-bearing formations. It incorporates the gas–water two-phase seepage phenomena, geomechanical loading, and temperature-difference disturbance during deep drilling process. Comparing the predictions of the previous saturated THM model and the presented model, the maximum relative errors of pore pressure, effective radial stress, effective tangential stress, and temperature are 30.2%, 34.6%, 3.4%, and 0.5%, respectively. The maximum prediction deviation in the width and depth of the failure zone occurs at the early time (t = 10−5 d). The unsaturated thermal coupling effect, although less influential on pore pressure and effective radial stress, makes a great contribution to the effective tangential stress with a maximum relative error of 10.1% for the temperature-difference of 30 K, and enhances the time dependence of the failure zone. The cooling condition is favorable to avoid shear collapse failure of the borehole, while the heating condition is not. The results also show that the gas-bearing formations with lower initial water saturation, higher rock permeability, or higher water phase relative permeability correspond to the higher risk of wellbore instability. The thermal conductivity and thermal expansion coefficient of the solid phase have a much greater effect on wellbore stability than those of the fluid phases. The effect of unsaturated THM coupling on wellbore stability may be more significant at lower rock permeabilities. The research findings provide insight into the wellbore stability analysis during drilling in deep gas-bearing formations.
A fully rigorous unsaturated thermo-hydro-mechanical (THM) coupling model based on thermodynamics is developed.
The unsaturated THM responses of pore pressure, stress components, and failure zone of a borehole were clarified.
The prediction differences between the presented model and previous saturated THM and unsaturated HM models were quantitatively analyzed.
The influence of two-phase seepage and thermal transport on wellbore stability were discussed parametrically.
Fully Coupled Thermo-hydro-mechanical Model for Wellbore Stability Analysis in Deep Gas-Bearing Unsaturated Formations Based on Thermodynamics
Rock Mech Rock Eng
Ma, Tianshou (author) / Liu, Jinhua (author) / Fu, Jianhong (author) / Qiu, Yi (author) / Fan, Xiangyu (author) / Martyushev, Dmitriy A. (author)
Rock Mechanics and Rock Engineering ; 58 ; 33-64
2025-01-01
32 pages
Article (Journal)
Electronic Resource
English
Applications of a coupled thermo-hydro-mechanical model to wellbore stability
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