Presented are features of heterogeneous structure of fractured granitic basement reservoir, obtained on the basis of laboratory studies of most representative core collection, retaining typical voids under 100% core recovery. Oil displacement mechanics and processes are experimentaly studied, wettability para meters and expulsion factor under conditions of backflow capillary imbibition of oil by water in microfractured blocks and water filtration through oil bearing macrofractures and caves are examined. Empirical dependance of expulsion factors on macrovoids content and orientation and, also, on microvoids volume distribution is obtained. Expulsion factors for different reservoir zones are determined, optimum displacement Velocities are evaluated, which provide for microfractured blocks coverage by capillary-exchange processes..