Abstract: A method of drilling well bore (20) through and below permeable formation (22) bearing such fluids as gas, oil, water wherein drill cuttings may be evacuated by formation fluid (23) being produced through the drill string (26) either by decreasing well head back pressure or by gas lift. Production rate is kept substantially stable by operating choke valves (140) and (142) placed after separator (52). Formation fluid being produced while drilling may be pumped into well bore (20) through annulus (31) or utilized. The unique injector included in the drill string provides for possibility to pump simultaneously into annulus (31) lifting gas and produced liquid and may be operated from the surface. A method and system (90) comprising a plurality of special 3-way valves included in drill string (26), are provided for making connections without interrupting flushing the well bore.