OIL WELL SCREW PUMPING UNIT Russian patent published in 2000 - IPC

FIELD: oil producing industry. SUBSTANCE: oil well screw pumping unit has tubing string on lower end of which single-screw pump is mounted. This pump has holder connected with tubing string, and screw which is rigidly secured inside casing pipe by means of locking device after lowering the tubing string to required depth. Locking device has three spring-loaded rollers moving along casing pipe walls, when tubing string is being lowered to required depth, and provided preliminary fastening of device when turbine string is stopped. Locking device has also screw-and-wedge mechanisms with retainers. With subsequent of tubing string, screw-and- wedge mechanism receives torque from turbine string through screw- holder pair, pushes retainers apart and finally secures locking device with pump screw inside casing pipe. Holder of pump which is secured in oil well continues turning together with tubing string, and pump delivers oil- containing liquid to surface. With tubing string being turned in opposite direction, screw-and-wedge mechanism releases retainers from contact with casing pipe making it possible to lift tubing string with pump to surface. EFFECT: enhanced reliability of preliminary and final fastening of pump fixed member. 2 cl, 1 dwg