Abstract：A fully coupled Thermo-Hydro-Mechanical model is presented in a single-phase，non-boiling linear thermoelastic medium，which incorporates cross-coupled fluid flow equation，energy conservation equation and mechanical equilibrium equation with many cross-coupling terms. A series of constitutive relations and cross-coupling relations between material properties and independent variables are defined in the model. The coupled multiphysics model is simultaneously simulated by using FEMLAB，the first engineering tool that performs partial differential equation-based multiphysics modeling in an interactive environment，which the mathematical model is translated into a set of partial differential equations. The pore pressure，displacements and temperature，which should theoretically approach the most realistic results，can be solved simultaneously by using FEMLAB，in which the errors in other coupling algorithms can be avoided. An example with known analytical and numerical results is used to validate the multiphysics model. In particular，cold water injection into wellbore is modeled with realistic time steps indicating that the coupled processes have significant effects on the stresses of borehole wall and wellbore stability.
