Downhole actuation system

Abstract

A downhole actuation system wherein a counting sleeve comprises at least one radial opening in which at least one seat element is arranged, the at least one seat element being capable of taking up a first, active position in which the at least one seat element projects into a longitudinal through-channel of the counting sleeve and a second, passive position in which the at least one seat element is retracted from the through-channel, the at least one seat element in its first position forming an annular seat configured to engage the actuating body.

1 . A downhole actuation system, designed to be actuated by an axial movement of a counting sleeve, where the counting sleeve is arranged in a pipe section in a well, the pipe section forming a housing for the counting sleeve, where the axial movement of the counting sleeve is designed to be initiated by an actuating body in the pipe section, wherein the counting sleeve comprises:
 at least one radial opening in which at least one seat element is arranged, the at least one seat element being capable of taking up a first, active position in which the at least one seat element projects into a longitudinal through-channel of the counting sleeve and a second, passive position in which the at least one seat element is retracted from the through-channel, the at least one seat element in its first position forming an annular seat configured to engage the actuating body.   
     
     
         2 . The actuation system according to  claim 1 , wherein the at least one seat element is an elongate element arranged along an inner circumference of the counting sleeve. 
     
     
         3 . The actuation system according to  claim 2 , wherein the at least one seat element is a split ring. 
     
     
         4 . The actuation system according to  claim 3 , wherein the split ring is a C-ring. 
     
     
         5 . The actuation system according to  claim 1 , wherein the at least one radial opening comprises a plurality of holes arranged circumferentially around the counting sleeve, wherein each hole has a seat element arranged therein. 
     
     
         6 . The actuation system according to  claim 1 , wherein the actuating body is a ball. 
     
     
         7 . The actuation system according to  claim 1 , wherein the actuating body is decomposable. 
     
     
         8 . The actuation system according to  claim 1 , wherein the counting sleeve is configured to start and carry out its axial movement when the actuating body lands on the annular seat whilst the at least one seat element is in its first position. 
     
     
         9 . The actuation system according to  claim 1 , wherein the counting sleeve is configured to end and stop its axial movement when the at least one seat element that forms the annular seat retracts to the second position, whereby the actuating body is released and allowed to move further down in the well. 
     
     
         10 . The actuation system according to  claim 1 , wherein the counting sleeve further comprises two or more longitudinally spaced radial openings, each of which having at least one seat element arranged therein. 
     
     
         11 . The actuation system according to  claim 10 , wherein the counting sleeve comprises a final seat, the final seat comprising:
 a split ring, the split ring being configured to rest on one or more shoulders and to be compressed to an inner diameter that is smaller than the diameter of the actuating body.   
     
     
         12 . The actuation system according to  claim 10 , wherein the actuation system is configured to form a new annular seat when the actuating body has axially displaced the counting sleeve a predetermined distance. 
     
     
         13 . The actuation system according to  claim 12 , wherein the predetermined distance corresponds to the distance between two rows of holes in which one or more seat elements are arranged. 
     
     
         14 . The actuation system according to  claim 1 , comprising a cam in the pipe section outside the counting sleeve, the cam configured to engage the at least one seat element and bring the at least one seat element:
 from the first position to the second position, and/or   from the second position to the first position.   
     
     
         15 . The actuation system according to  claim 5 , wherein the counting sleeve comprises additional circumferentially arranged holes comprising ball seat elements, the distance between the additional circumferentially arranged holes and an underlying annular ball seat being adapted such that a ball lying on the annular ball seat will press the ball seat elements out of the wellbore and into external grooves provided in the pipe section forming a housing for the counting sleeve. 
     
     
         16 . The actuation system according to  claim 15 , wherein the ball seat elements that are arranged in the additional circumferentially arranged holes and are pressed into the external grooves are configured to prevent rotation of the counting sleeve. 
     
     
         17 . The actuation system according to  claim 16 , wherein the ball seat elements that are arranged in the additional circumferentially arranged holes and are pressed into the external grooves prevent axial displacement of the counting sleeve over a limited distance by adaptation of the length of the grooves, the grooves in a downward axial direction ending when the underlying annular seat has been established, the termination of the grooves forming seats for the ball seat elements. 
     
     
         18 . The actuation system according to  claim 15 , wherein the ball seat elements are released into the wellbore and out of the grooves when the actuating body that forces them into the grooves has been dropped further down in the well. 
     
     
         19 . The actuation system according to  claim 1 , wherein the number of sets of longitudinally spaced radial openings corresponds to the number of actuating bodies which is desired should pass before the actuation system is triggered or actuated. 
     
     
         20 . The actuation system according to  claim 1 , further comprising friction elements arranged between the counting sleeve and the pipe section, the friction elements configured to control, brake and/or stop the axial movement of the counting sleeve, the friction elements consisting of at least one of: a split ring, a rough surface, a coating, ridges, c-clip rings, shear rings, or shear pins.