Pilot studies on solvent and steam injection were conducted in the heavy-oil Usa oil field (Permo-Carboniferons, fractured, porous-cavernous carbonate reservoir). The results of this study, which may help in developing efficiently high-viscosity oil accumulations, are presented. Delineating the high-permeability zones was important in choosing location of injection and producing wells. Detailed knowledge of reservoir characteristics (e.g.,fracture density, distribution, and orientation) is of utmost importance.