to set the packers in another the plug is sheared by movement of the sleeve through contact with a pressure differential sensitive piston that shifts in response to an increase in annular pressure application_number US 69370485 A description in fig1 a reference t designates the string of a production tubing the string t is followed by several sections of drill collars dp1 to dp3 between which are placed for example a slip joint sj and a reversing valve rv allowing backflow by internal pressure cycling as shown in fig1 b the pipe section dp3 is followed by the control means 1 according to the invention after these is first of all placed the dst tool which comprises a test device downhole valve controlled by the annular pressure dst 1 and a hydrostatic reference tool dst 2 a pressure recorder pr is then provided it is also optionally possible to add a hydraulic jar hj as well as a safety joint sj we then have the packer apparatus according to the invention shown by reference numeral 2 which is followed by a perforated pipe stp under which may be placed pressure recorders a line or pipe 19 connects the devices 1 and 2 of fig1 b it is noted that this pipe is advantageously wound helically at the level of the devices dst 2 and hj to allow variations in the length of the production tubing fig2 shows a main mandrel or pipe 10 whose head is equipped with threading 100 on which is placed an annular end fitting 11 on the outside the annular fitting 11 receives a cylindrical wall 12 this same.