Plug, and methods for setting and releasing the plug

Abstract

A plug includes a slip actuator for setting and release of slips, and a locking element in contact with the slip actuator. The locking element includes multiple parts with internal threads which constitute an enclosure around threads of a pipe. On the radial outer surface of the locking element are provided resilient elements. When setting the plug, the locking element is capable of sliding over the pipe threads for movement of the slip actuator and setting of the slips, until the locking element comes into engagement with a locking sleeve, fixed relative to the pipe, which prevents rotation of the locking element. When releasing the plug, the locking element is released from the locking sleeve, and the locking element rotates off the pipe threads, and the slip actuator follows the movement of the locking element and releases the slips.

1 . A plug for a hydrocarbon well, wherein the plug can be held fixed relative to a casing/borehole wall, and wherein the plug further comprises:
 a slip actuator for setting and releasing slips,   a locking element in contact with the slip actuator, and   one or more resilient packing elements which are adapted for sealing against the casing/borehole wall,   wherein the locking element comprises multiple parts having internal threads which constitute an enclosure around threads on a pipe, and wherein on the radial outer surface of the locking element there are arranged resilient elements ( 6 ), and   wherein the locking element, when setting the plug, is capable of sliding over the pipe threads for movement of the slip actuator and setting of the slips, and that the locking element comes into engagement with a locking sleeve in order to prevent rotation of the locking element;   whilst when releasing the plug, the locking sleeve is released from the locking element, the locking element rotates off the pipe threads and the slips are released.   
     
     
         2 . The plug according to  claim 1 , wherein the plug is held fixed to the casing/borehole wall by a holding member with radially acting elements. 
     
     
         3 . The plug according to  claim 1 , wherein the setting and the release of the plug is controlled by axial movement of the pipe. 
     
     
         4 . The plug according to one of  claim 1 , wherein the holding member is in end contact with a guide sleeve and that the locking element is in end contact with the other end of the guide sleeve. 
     
     
         5 . The plug according to  claim 1 , wherein a pin is provided on the pipe which follows the movement of the pipe, the pin being movable in a recess in the guide sleeve. 
     
     
         6 . The plug according to  claim 1 , wherein the locking element and the locking sleeve have corresponding locking grooves and locking pins. 
     
     
         7 . The plug according to  claim 1 , wherein the activation of the setting of the plug is controlled by a first timer that is activated by a specific pressure on the pipe over a given period of time. 
     
     
         8 . The plug according to  claim 7 , wherein the at least one timer is hydraulic, and that the pressure acting on the timer controls the transfer of hydraulic fluid from a first chamber to a second chamber in the timer, and where the setting starts when all hydraulic fluid has been transferred between the chambers. 
     
     
         9 . The plug according to  claim 1 , wherein the activation of the release of the plug is controlled by a second timer which is activated by a specific pressure on the pipe over a given period of time. 
     
     
         10 . The plug according to  claim 7 , wherein the at least one timer is hydraulic, and that the pressure that acts on the timer controls the transfer of hydraulic fluid from a first chamber to a second chamber in the timer, and where the release starts when all hydraulic fluid has been transferred between the chambers. 
     
     
         11 . The plug according to  claim 1 , wherein the resilient packing elements are compressed by setting of the slips, and on the release the resilient packing elements expand axially, this axial expansion motion rotating the locking element off the pipe threads. 
     
     
         12 . A method for setting the plug according to  claim 1 , wherein the setting is activated by an axial movement of the pipe, wherein the movement further causes a guide sleeve to apply a force on the locking element which, by virtue of its high-pitch threads against the pipe, will slide over the threads and exert a force on the slip actuator which presses the slips out into firm engagement with the casing/borehole wall. 
     
     
         13 . A method for release of the plug according to  claim 1 , wherein an axial movement of the pipe activates the release of the locking sleeve from the locking element, such that the locking element is free to rotate off the threads on the pipe and the slips are released. 
     
     
         14 . A method according to  claim 13 , wherein the locking element rotates off the threads on the pipe in that resilient packing elements on the plug expand axially and act on the locking element.