Uncoupling device for connecting a drilling tool to the end of a drilling column and a drilling system comprising such an uncoupling device

Abstract

Collection device for connecting a drilling tool, such as a bit, to the end of a drilling column, in which the connection device comprises a first element, with a first end, intended to be connected to the end of the drilling column, and a second element, with a second end, intended to be connected to the drilling tool, in which the second element is fixed to the first element so as to allow a translational movement in a longitudinal direction in order to make it possible to change the distance between the first end and this second end, characterized in that the connection device comprises a “pusher” structure for transmitting a thrust force from this first element towards the second element, comprising a set of “Belleville” washers making it possible to ensure that said thrust force, from the first element toward the second element, is substantially constant in any position of the second element with respect to the first element.

1 . Uncoupling device for connecting a drilling tool, such as a bit, to the end of a drill string, wherein the uncoupling device comprises a first element, with a first end, intended to be connected to the end of the drill string, and a second element, with a second end, intended to be connected to the drilling tool, wherein the second element is fixed to the first element for allowing a translational movement, in a longitudinal direction for allowing to modify the distance between this first end and this second end, characterized in that the uncoupling device comprises a “pusher” structure for transmitting a compressive strain from this first element towards the second element, comprising a set of “Belleville” washers, designed and used in their operating range thereof such that they allow to ensure that said compressive strain, from this first element towards the second element is substantially constant in any position of the second element relative to the first element. 
     
     
         2 . Uncoupling device according to  claim 1 , wherein said compressive force is provided with an acceptable tolerance range of maximum 20%, but preferably maximum 10%, ideally of maximum 2%. 
     
     
         3 . Uncoupling device according to  claim 1 , wherein the “pusher” structure comprises a set of “Belleville” washers positioned relative to each other so as to form a column of washers. 
     
     
         4 . Uncoupling device according to  claim 3 , wherein the washers are positioned relative to each other so as to obtain a pack of washers. 
     
     
         5 . Uncoupling device according to  claim 2 , wherein the washers are positioned so as to obtain columns of packs of washers. 
     
     
         6 . Device according to  claim 1 , wherein the “pusher” structure comprises a plurality of modules mounted in sequence, in the longitudinal direction, between the first element and the second element, each module being adapted for transferring a portion of the compressive strain from this first element towards this second element, so that the sum of said portions of the compressive strain of the modules is equal to the compressive strain of the “pusher” assembly. 
     
     
         7 . Device according to  claim 6 , wherein the device is provided with “locking” elements adapted for locking the functionality of at least one module for allowing to the unlocked modules only to transfer the compressive strain from the first element towards the second element. 
     
     
         8 . Uncoupling device according to  claim 6 , wherein the modules of the plurality are identical, each of the modules supplying an identical part of the compressive strain. 
     
     
         9 . Device according to  claim 6 , wherein the modules are different so as to ensure that one of the modules is adapted for transferring a compressive strain, with another magnitude than the one of the other modules. 
     
     
         10 . Device according to  claim 6 , wherein each module comprises an inner tube portion, and an outer tube portion surrounding the inner tube portion, and wherein:
 the outer tube portions are rigidly connected in sequence with each other and with the first element,   the inner tube portions are rigidly connected in sequence with each other and with the second element, and   each module transfers said part of the compressive strain to the inner tube portion of said module.   
     
     
         11 . Device according to  claim 1 , wherein the “pusher” structure is housed in an annular volume extending radially between an inner tube, destined to channelling at least one fluid inside said inner tube, and an outer tube, rigidly connected with the first element and encasing said “pusher” structure. 
     
     
         12 . Drilling system comprising an uncoupling device, according to  claim 1 , and further comprising:
 a drill string comprising at least one tube, said drill string being connected to the first element of the uncoupling device,   a drilling tool, such as a bit, for drilling a geological formation, the drilling tool being connected to the second element of the uncoupling device, and   a device for retaining the drill string, at the drilling wellhead, suitable for controlling the movement up and down of the drill string in the wellbore.   
     
     
         13 . System according to  claim 12 , wherein the uncoupling device comprises at least one displacement sensor for determining the position of the second element with respect to the first element over time so as to obtain the feed rate of the second element with respect to the first. 
     
     
         14 . System according to the  claim 13 , wherein the uncoupling device comprises a rotation, thrust measurement and torque measurement sensor for estimating the resistance of the drilled rock and the degree of wear of the drilling tool by means of a cutting model. 
     
     
         15 . System according to  claim 12 , wherein the uncoupling device comprises at least one displacement sensor for determining a position of the second element with respect to the first element, wherein the system comprises transmission means for transmitting said position of the second element to the retaining device for controlling a retaining effort of the drill string. 
     
     
         16 . System according to  claim 15 , wherein the retaining effort of the drill string is increased if the position transmitted to the retaining device indicates that the second element is in the vicinity of the first element, and the effort of the drill string is reduced if the position transmitted to the retaining device indicates that the second element is far from the first element.