METHOD FOR CONNECTING WATER-PROTECTIVE PIPE STRING WITH WELL-HEAD OF UNDERWATER WELL Russian patent published in 1998 - IPC

FIELD: oil and gas production industry. SUBSTANCE: according to method, first pipe of water-protective pipe string is profiled prior to its lowering with formation of longitudinal corrugations. Hermetic agent is placed into folds of corrugations. Upper end of well-head section over its length of conjugation with profiled pipe is made with inner diameter which is equal to outer diameter of water-protective pipe string. Length of end of upper protrusion of well-head section is determined with taking into consideration pulling forces required for uncoupling of connection. Water-protective pipe string is lowered until its profiled pipe enters upper end of well-head piece. By pumping in liquid under pressure, profiled pipe is expanded radially so that its wall becomes pressed against wall of upper end of well-head piece. Then, profiled pipe is beaded by beading tool until its wall is tightly pressed against wall of upper end of well-head piece and its inner diameter becomes equal to diameter equivalent to inner diameter of main part of well-head piece. Uncoupling of connection is obtained by extracting water-protective pipe string from well-head piece by pulling aforesaid pipe string by means of drilling rig drawworks. Method allows for improving reliability of connection due to excluding devices which are complex in design and operation. EFFECT: high efficiency. 2 dwg