This work investigates the geothermal resources at Vieux-Habitants, in the Basse-Terre island, Guadeloupe, French Antilles. Early field observations have shown a particular variation of the temperature as a function of depth in the geothermal plant implanted in the area. To better exploit the resource, the relationships between the heat flux and the hydrogeologic system have to be clarified. Various scenarios involving can explain the observed temperatures and water chemistry. We simulate the temperature field on a 2D model of the geothermal field with the software HYDROTHERM. We conduct a sensitivity analysis by varying various parameters, including the permeability of the host rock (vertical and horizontal), the presence of a geological heterogeneity as horizontal drain or the precipitation flux. The results of the simulations confirm the possibility of having a vertical heat flux corresponding to the temperature variations observed.