start up electrically or pneumatically actuated valves may be substituted therefor in an electrically actuated system suitable relays not shown would open and close the valves upon selective energization by electrical current delivered through an insulated lead or cable not shown positioned within the well casing 14 with a pneumatically actuated system however a pressurized pneumatic conduit not shown would be positioned in the well casing 14 to communicate with and control each of the valves operable at a predetermined pressures conventional means for imposing a vacuum such as vacuum pump 36 having a pump inlet connected through a conduit 38 communicating with the inside of the tubing 14 is provided to impose a vacuum on the oil bearing liquid collected in the sump 22 the vacuum serves to draw oil bearing liquid collected in the sump 22 into the inlet opening 28 and up the tubing 24 for recovery via the wellhead 26 and increases the rate at which oil bearing liquid enters the well casing 14 through perforations 20 preferably the amount of vacuum imposed by vacuum pump 36 upon the tubing 24 is selectively adjusted by a valve 40 in the conduit 38 to retain intake opening 28 partially submerged in oil bearing liquid collected in sump 22 the vacuum pump 36 compresses the gas transported through the conduit 38 to the desired degree and.