This paper presents the study of the coupled hydro-mechanical behavior of a faulted HP-HT hydrocarbon reservoir during depletion. Because of the large expected depletion, a number of phenomena may be enhanced, all related to the changes during production, of the in-situ stresses, which control the mechanical response of the reservoir. This includes essentially two types of deformation, the first one being the reactivation of in the reservoir existing faults, while the second one is the reservoir compaction. The objective of this paper is principally to present the study of the first phenomenon, and more particularly their hydro-mechanical aspects. The study has been carried out with the help of numerical simulations of the fully coupled hydro-mechanical behavior of 2D reservoir models, using the finite element code LAGAMINE.