Device by tubing

A tubing system for use in an oil or gas well includes a tubing, provided with a holder portion; a casing, around the tubing; a packer, disposed in an annulus defined by the tubing and the casing; and a telescopic extension, positioned within the tubing and extendable beyond a distal portion of the tubing. The telescopic extension is provided with structures for fastening the telescopic extension to the holder portion of the tubing, and structures for accepting a tool by which the telescopic extension is axially displaceable to withdraw the telescopic extension from the distal portion of the tubing. The tubing system is further provided with a first part of a coupling, in the holder portion of the tubing, provided with lines which pass through a portion of the annulus above the packing to communicate with equipment on the surface; and a second part of the coupling, in the telescopic extension, provided with lines which pass within the telescopic extension to equipment provided within a length of the telescopic extension. In the embodiments described, the lines of the tubing system can be electric conductors or hydraulic lines.