Thermo-Hydro-Mechanical Phase-Field Fracture Model with Micromechanical Strain Energy Degradation

Core Concepts

This work extends the hydro-mechanical phase-field fracture model to non-isothermal conditions with micromechanics-based poroelasticity, where the Biot's coefficient and porosity are degraded based on the phase-field variable and the energy decomposition scheme. The model also employs an isotropic diffusion method to stabilize the advection-dominated heat flux and adapts the fixed stress split method to account for thermal stress.

Abstract

The key highlights and insights of this content are:

The authors extend the existing hydro-mechanical phase-field fracture model to thermo-poro-elastic media by introducing the thermal strain. The degradation of the thermo-poro-elastic strain energy is achieved through micromechanically derived Biot's coefficient, which depends on both the phase-field (damage) and the energy decomposition scheme.

A new approach is proposed to update the porosity that only depends on the strain change rather than the damage evolution, which is different from the existing models that rely on the phase-field profile.

An isotropic diffusion method is employed to stabilize the advective dominated heat flow in fractures, and the fixed stress split stabilization method is adapted to account for thermal stress in the numerical implementation.

The proposed model is verified against a series of analytical solutions, including Terzaghi's consolidation, thermal consolidation, and the plane strain hydraulic fracture propagation (KGD fracture). The results show that the new porosity update improves the accuracy in representing the sharp fracture behaviors compared to the existing phase-field dependent porosity models.

Numerical experiments demonstrate the effectiveness of the stabilization method and the intricate thermo-hydro-mechanical interactions during hydraulic fracturing with and without a pre-existing weak interface.

Stats

The authors provide the following key metrics and figures to support their analysis:

Dimensionless viscosity M = 3.8 × 10−7 for the toughness-dominated hydraulic fracture regime
Effective critical surface energy release rate Geff
c
adjusted based on the mesh size he and characteristic length ℓ
Comparisons of numerical results and analytical solutions for Terzaghi's consolidation, thermal consolidation, and KGD hydraulic fracture propagation

Quotes

None.

Key Insights Distilled From

A phase-field fracture model in thermo-poro-elastic media with micromechanical strain energy degradation

by Yuhao Liu,Ke... at arxiv.org 04-25-2024

https://arxiv.org/pdf/2404.15322.pdf

Deeper Inquiries

How would the proposed thermo-hydro-mechanical phase-field model perform in more complex geological settings, such as fractured or heterogeneous reservoirs

The proposed thermo-hydro-mechanical phase-field model would likely perform well in more complex geological settings, such as fractured or heterogeneous reservoirs, due to its ability to capture intricate interactions between thermal, hydraulic, and mechanical processes. In fractured reservoirs, the model's phase-field approach can effectively simulate the propagation of fractures and their interactions with the surrounding rock matrix. The inclusion of micromechanically derived Biot's coefficient and porosity updates enhances the model's ability to represent the evolving poroelastic properties in such complex geological settings. Additionally, the model's capability to account for thermal effects, fluid flow, and mechanical deformation provides a comprehensive framework for analyzing the behavior of fractured or heterogeneous reservoirs under thermo-hydro-mechanical conditions.

What are the potential limitations or drawbacks of the micromechanically derived Biot's coefficient and porosity update approaches used in this study

While the micromechanically derived Biot's coefficient and porosity update approaches used in this study offer several advantages, there are potential limitations and drawbacks to consider. One limitation could be the complexity of incorporating detailed micromechanical models into larger-scale simulations, which may increase computational costs and complexity. The accuracy of the micromechanical approach may also depend on the assumptions and simplifications made in the model, potentially leading to discrepancies with real-world behavior. Additionally, the porosity update approach solely based on strain change may oversimplify the poroelastic behavior, especially in scenarios where damage evolution significantly influences porosity changes. It is essential to validate these approaches against experimental data and field observations to ensure their reliability and applicability in practical geological settings.

Could the insights from this work be extended to other types of fracturing processes, such as those involving chemical reactions or multiphase fluids

The insights gained from this work could be extended to other types of fracturing processes, including those involving chemical reactions or multiphase fluids. By incorporating additional mechanisms such as reactive chemistry or multiphase flow, the thermo-hydro-mechanical phase-field model could be adapted to simulate complex fracturing scenarios like acid fracturing or CO2 fracturing. The model's ability to capture the coupled effects of thermal, hydraulic, and mechanical processes makes it a versatile tool for studying a wide range of fracturing phenomena. Furthermore, the stabilization methods and numerical techniques developed in this study could be applied to enhance the simulation of various fracturing processes, enabling more comprehensive and accurate predictions in different geological contexts.