Coupled thermal-hydraulic-mechanical (THM) processes play a significant role in geothermal energy extraction. Accurate prediction and analysis of deformation and stress and thermal and flow behaviours remain challenging because of the complex geological structures and the interaction of coupled THM processes.

Over the past decades, numerous simulation models have been developed to study and understand the coupled THM phenomenon in the process of heat extraction from porous or fractured porous reservoirs. Many approaches have been proposed to model the coupled processes in reservoir simulation. For instance, finite differences, or finite elements for the mechanic problems, and finite volumes for the flow and thermal problems. Moreover, finite element models are being used to study fully coupled problems. Meanwhile, the coupling strategies for the solution of the flow, mechanics, and thermal issues have become a popular research topic. These coupling strategies are known as one-way coupling, sequential coupling, three-way coupling, and fully coupled approaches.

The aim of this Special Issue is to bring together research exploring our understanding of the coupled phenomenon in complex geological systems and our knowledge of geothermal extraction. We welcome both original research and review articles.

Potential topics include but are not limited to the following:

• Numerical modelling of coupled processes associated with geothermal extraction
• Advanced numerical modelling in predicting heat extraction performance
• Coupled thermo-hydro-mechanical (THM) processes in porous media
• Coupled processes in complex fracture networks
• Numerical simulation of coupled processes in other geological reservoirs
• Advances in numerical computation of coupled processes