DEVICE TO SEAL INTERNAL SPACE OF TUBING STRING IN PROCESS OF SINKING OR LIFTING FROM WELL UNDER PRESSURE Russian patent published in 2002 - IPC

FIELD: oil and gas production. SUBSTANCE: invention is meant to shut off internal duct of tubing string during emergency operations in oil field with lifting of tubing string from well under pressure. Device has body, members to fix body at the bottom of tubing string positioned in radial hole of body and in grooves of ring bushing, spring-loaded and mounted for radial movement. Sealing elements are installed in upper part of body. Ring bushing is spring-loaded and has capability of axial movement with reference to body. Device is fitted with sectional coupling-catcher that is joined to lower part of tubing string by means of thread. Cylindrical recess with formation of shoulder on its butts is made in internal duct of coupler-catcher. Internal duct narrows with formation of cone face under recess. Setting hole is located beneath cone face. Coupling-catcher makes it feasible to achieve reliable leak-proofness between body of device and tubing string thanks to seal of ring cylindrical clearance between lower part of body of device and setting hole in lower part of coupling-catcher. EFFECT: increased leak-proofness between body of device and tubing string. 4 dwg