Downhole injection tool and method for injecting a fluid in an annulus surrounding a downhole tubular

Abstract

A downhole injection tool for injecting a treatment fluid in a space surrounding a downhole tubular installed in a borehole in the Earth is based on an elongate tool housing extending around a central longitudinal tool axis. At least two stings are provided, each having a fluid channel. At least two treatment fluid cannisters are provided in the downhole injection tool, for holding the treatment fluid that is to be injected. A first cannister of the at least two treatment fluid cannisters is fluidly connected with the exterior of the tool housing via a first sting of the at least two stings, but not via a second sting of the at least two stings. A second cannister of the at least two treatment fluid cannisters is fluidly connected with the exterior of the tool housing via the second sting, but not via the first sting.

1 . A downhole injection tool for injecting a treatment fluid in a space surrounding a downhole tubular installed in a borehole in the Earth, comprising:
 an elongate tool housing extending around a central longitudinal tool axis;   at least two stings, each of the stings comprising a fluid channel to establish fluid communication from within the tool housing to an exterior of the tool housing through the fluid channel, wherein each said sting is movable in a radially outward direction, away from the central longitudinal tool axis, from a retracted position to an extended position whereby each sting extends to outside the elongate tool housing;   at least two treatment fluid cannisters, for holding the treatment fluid that is to be injected, wherein a first cannister of the at least two treatment fluid cannisters is fluidly connected with the exterior of the tool housing via a first sting of the at least two stings, but not via a second sting of the at least two stings, and wherein a second cannister of the at least two treatment fluid cannisters is fluidly connected with the exterior of the tool housing via the second sting, but not via the first sting.   
     
     
         2 . The downhole injection tool of  claim 1 , further comprising a hydraulic drive mechanism functionally connected to the at least two stings to move each of the at least two stings from the retraced position to the extended position, said hydraulic drive mechanism comprising a piston and pump, which piston is actuated by a hydraulic fluid that is displaced by said pump. 
     
     
         3 . The downhole injection tool of  claim 2 , wherein both the first cannister and the second cannister are in selective fluid communication with said pump. 
     
     
         4 . The downhole injection tool of  claim 3 , wherein the pump is in selective fluid communication with both the first cannister and the second cannister via a selectable valve which selectively isolates both the first cannister and the second cannister from the pump or opens both the first cannister and the second cannister to the pump. 
     
     
         5 . The downhole injection tool of  claim 1 , wherein the first sting and the second sting are movable in mutually differing directions. 
     
     
         6 . The downhole injection tool of  claim 1 , wherein the first sting and the second sting are movable in mutually opposing directions. 
     
     
         7 . A method of injecting a treatment fluid in an annulus surrounding a downhole tubular arranged within a borehole in the Earth, said method comprising:
 providing a downhole injection tool comprising:
 an elongate tool housing extending around a central longitudinal tool axis; 
 at least two stings, each of the stings comprising a fluid channel to establish fluid communication from within the tool housing to an exterior of the tool housing through the fluid channel, wherein each said sting is movable in a radially outward direction, away from the central longitudinal tool axis, from a retracted position to an extended position whereby each sting extends to outside the elongate tool housing, 
 at least two treatment fluid cannisters, for holding the treatment fluid that is to be injected, wherein a first cannister of the at least two treatment fluid cannisters is fluidly connected with the exterior of the tool housing via a first string of the at least two stings, but not via a second sting of the at least two stings, and wherein a second cannister of the at least two treatment fluid cannisters is fluidly connected with the exterior of the tool housing via the second sting, but not via the first sting; 
   lowering the downhole injection tool into the borehole through the downhole tubular to a selected depth;   at the selected depth, extending the first sting and the second sting through a wall of the downhole tubular, to establish fluid communication between downhole injection tool and the annulus surrounding the downhole tubular;   injecting the treatment fluid from the downhole injection tool from the at least two treatment fluid cannisters through the first sting into the annulus surrounding the downhole tubular and through the second sting into the annulus;   retrieving the downhole injection tool from the downhole tubular.   
     
     
         8 . The method of  claim 7 , further comprising moving each of the at least two stings from the retraced position to the extended position by means of a hydraulic drive mechanism. 
     
     
         9 . The method of  claim 8 , further comprising actuating a piston comprised in said hydraulic drive mechanism by a hydraulic fluid that is displaced by a pump. 
     
     
         10 . The method of  claim 9 , wherein both the first cannister and the second cannister are in selective fluid communication with said pump. 
     
     
         11 . The method of  claim 10 , wherein the pump is in selective fluid communication with both the first cannister and the second cannister via a selectable valve which selectively isolates both the first cannister and the second cannister from the pump or opens both the first cannister and the second cannister to the pump. 
     
     
         12 . The method of  claim 8 , wherein the first sting and the second sting are moved in mutually differing directions. 
     
     
         13 . The method of  claim 8 , wherein the first sting and the second sting are moved in mutually opposing directions.