Since new environmental regulations were established prohibiting the use of drilling fluids that had elements such as diesel in their composition, it was necessary to search for new components that, besides being effective in their function, had a biodegradability characteristic, thus being less harmful to the environment. The base of the drilling fluid chosen to fit the new rules was studied in this thesis in order to characterize its stability and rheological behavior. The fluid used is an inverse emulsion whose continuous phase is the olefin and the dispersed phase, brine, plus a primary emulsifier, Cybermul, and a secondary one, Cyberplus. To delay the destabilization process, mainly characterized by sedimentation, in a second moment, hydrated lime was added to the emulsion s composition. The tests performed were divided into two stages: the first, emulsions prepared at 5000 rpm, 7500 rpm and 10,000 rpm without lime in their composition were analyzed and the second, emulsions prepared at the same rotation velocities however with hydrated lime in their composition. The main variable adopted was the speed of rotation in order to confirm the knowledge that the higher is the speed of agitation during emulsification, the smaller are the drops generated and, consequently, the more stable is the emulsion. The tests consisted of interfacial tension, bottle test, droplet size distribution (microscopy and dynamic light scattering) and rheological behavior tests, which include, creep tests, flow curve and stress and time sweep tests. The results obtained allowed to relate the size of the drops with the emulsion s stability and with its viscosity.