In order to study the thermo-mechanical effects induced by the injection of a fluid like CO2 in a host rock whose temperature is higher than those of the fluid, a DEM modeling has been imple-mented based on a "particulate" approach (Particle Flow code - PFC). The methodology devel-oped to build a particle rock model consistent with the rock petrophysical characteristics and the thermo-mechanical behavior is proposed in this paper. The three main steps are described: rock conceptualization (association of rock petrophysical and textural elements with numerical ob-jects), estimating geometrical and physical properties of the rock model from the petrographic characteristics, and finally mechanical and thermo-mechanical calibration. An example of a modeling of drilling mechanical effect and thermo-mechanical effects induced by injection of a cold fluid in a host rock is finally presented.