The North Sokhs Field, located in the southern part of the Fergen depression, is composed of many horizons and has an anticlinal structure. The eighth horizon has highest oil saturation, with an average porosity of 17% and permeability of 80 md. Poor oil recovery was initially obtained from this horizon because the basic producing mechanism was solution gas drive. In 1961, when reservoir pressure was 94 kg/cmU2D and gas factor was 700-800mU3D/ton, pressure maintenance was initiated by injection of gas to the structure. Gas injection improved oil recovery considerably; however, high gas-oil ratios appeared in several wells. Next, peripheral water injection was started, and continued simultaneously with gas injection. The simultaneous injection of gas and water almost doubled oil production. Because of continued, high produced gas/oil ratios, gas injection was eventually discontinued, while water injection was continued. Water injection is building up reservoir pressure and improving oil recovery.