DEVICE FOR HEAT INSULATION OF TUBING STRING IN WELL Russian patent published in 1996 - IPC

FIELD: gas and oil producing industry; operation of oil and gas wells with intensive paraffin deposition. SUBSTANCE: device for heat insulation of tubing string in well includes inner and outer strings of tubing which form closed circular space. Ejector is located at the distance from the day surface below the depth of paraffin occurrence. Ejector receiving chamber has valve communicating ejector hollow with closed circular space. Outer pipe string forms together with inner string under circular space and communicated with tubing-borehole space by means of circulation valve. During device operation, fluid is removed from additional and closed circular chambers, and they are subsequently vacuumized to increase heat insulation of the inner tubing string and to prevent paraffin deposition. Closed circular space and additional one, due to availability of circulation valve may be used as free channel for heat carrier circulation. EFFECT: higher efficiency. 6 cl, 4 dwg