Improvements In Or Relating To Well Abandonment

Abstract

An apparatus and method for anchoring a string at a well for the purpose of cutting a tubular ( 30 ) which includes an anchor mechanism ( 110 ) being a tubular body ( 60 ) having a cone ( 116 ) arranged around the body, a plurality of selectively operable slips ( 112 ), and a plurality of pistons ( 44 ), there being a piston for each slip, each piston being operable to act to move each slip independently over the cone between a retracted configuration and an extended configuration wherein the outer surface ( 96 ) of each of the slips contacts the inner surface of the tubular ( 30 ). The method includes the action of cutting the tubular ( 30 ) with a cutting tool ( 102 ) which is stabilised by the slips ( 112 ).

1 . Apparatus for anchoring a string at a well for the purpose of cutting a tubular, including an anchor mechanism, the anchor mechanism comprising:
 a tubular body having a central bore between a first inlet and a first outlet, the first inlet and first outlet being adapted for connection in a drill string to be run into the tubular;   a cone arranged around the tubular body, the cone having an outer surface including a slope;   a plurality of selectively operable slips, each slip having an outer surface configured to grip an inner surface of the tubular and an inner surface matching the slope of the cone they are arranged upon; and   a plurality of pistons, there being a piston for each slip, each piston being operable to act to move each slip independently over the cone between a retracted configuration and an extended configuration wherein the outer surface of each of the slips contacts the inner surface of the tubular.   
     
     
         2 . Apparatus according to  claim 1  wherein the tubular body is rotatable relative to the cone. 
     
     
         3 . Apparatus according to  claim 1  wherein each piston comprises a piston rod contained within a cylinder arranged co-linearly with a central axis of the apparatus and each piston rod is arranged to act on a face of each slip. 
     
     
         4 . Apparatus according to  claim 1  wherein the pistons are hydraulically operated by action of fluid from the central bore. 
     
     
         5 . Apparatus according to  claim 1  wherein each piston includes an emergency release arrangement so as to ensure retraction of each slip when the apparatus is moved back from the extended configuration to the retracted configuration. 
     
     
         6 . Apparatus according to  claim 5  wherein the arrangement comprises a release piston configured to act on each piston rod. 
     
     
         7 . Apparatus according to  claim 6  wherein the release piston is hydraulically operated by action of fluid from the central bore. 
     
     
         8 . Apparatus according to  claim 1  wherein the apparatus includes a plurality of selectively operable centralisation pads, each pad having an outer surface configured to match an inner surface of the tubular and an inner surface matching the slope of the cone they are arranged upon; and
 the plurality of pistons including a piston for each centralisation pad, each piston associated with a centralisation pad being operable to move each centralisation pad independently over the cone between a retracted configuration and an extended configuration wherein the outer surface of each of the centralisation pads is at drift to the inner surface of tubular. 
 
     
     
         9 . Apparatus according to  claim 8  wherein the slope of the cone at each centralisation pad is steeper in gradient than the slope of the cone at each slip. 
     
     
         10 . Apparatus according to  claim 8  wherein there are an equal number of slips to centralisation pads on the apparatus and a centralisation pad is located between each slip and spaced equidistantly around a circumference of the tool body. 
     
     
         11 . A method for anchoring a string at a well and cutting a tubular, comprising the steps:
 (a) mounting apparatus on a drill string, the apparatus including an anchor mechanism, the anchor mechanism comprising:
 a tubular body having a central bore between a first inlet and a first outlet, the first inlet and first outlet being adapted for connection in a drill string to be run into the tubular; 
 a cone arranged around the tubular body, the cone having an outer surface including a slope; 
 a plurality of selectively operable slips, each slip having an outer surface configured to grip an inner surface of the tubular and an inner surface matching the slope of the cone they are arranged upon; and 
 a plurality of pistons, there being a piston for each slip, each piston being operable to act to move each slip independently over the cone between a retracted configuration and an extended configuration wherein the outer surface of each of the slips contacts the inner surface of the tubular; 
   (b) mounting a cutting tool on the drill string;   (c) running the drill string in the wellbore and locating the cutting tool at a location at which the tubular is to be cut;   (d) setting the slips independently to anchor the apparatus to an inner surface of the tubular to be cut;   (e) cutting the tubular using the cutting tool; and   (f) unsetting the slips to release the apparatus from the inner surface of the cut section of tubular.   
     
     
         12 . A method according to  claim 11  wherein the method includes the step of hydraulically actuating the pistons to contact the slips to the inner surface of the tubular. 
     
     
         13 . A method according to  claim 11  wherein the method includes the step of applying an over pull to the anchor mechanism once the slips have contacted the inner surface of the tubular. 
     
     
         14 . A method according to  claim 11  wherein the step of unsetting the slips is by applying a downward force to the tool. 
     
     
         15 . A method according to  claim 11  wherein the cutting tool is operated via rotation of the drill string with the anchor mechanism set against the tubular to provide stability to the cutting tool. 
     
     
         16 . A method according to  claim 11  wherein the method includes radially extending centralising pads independently on the anchor mechanism. 
     
     
         17 . A method according to  claim 11  wherein the method includes activating an emergency release arrangement to unset the anchor mechanism and draw the slips away s from the inner surface of the tubular in the event that they don't release. 
     
     
         18 . A method according to  claim 11  wherein the cut section of tubing is removed from the well by using the anchor mechanism as a spear.