Single trip annular seal repair method and associated equipment

Abstract

A single trip method of repairing a leaking annular seal located within an annulus that encircles an oil/as wellbore tubular body, examples of such seals including annular packers or cement seals. The method comprises providing deflector within a wellbore tubular body adjacent to one or more openings in the wall of the tubular body. Alloy beads are then deployed downhole via the tubular body so that the alloy beads are deflected via said openings into the annulus where they accumulate on top of the annular seal. The alloy is then heated to form an alloy plug above the annular seal. The present invention also provides an annular seal repair tool assembly for use in the repair method of the present invention.

1 . A method of repairing a leaking annular seal located within an annulus that encircles an oil/gas wellbore tubular body, said method comprising:
 deploying a heating tool comprising at least one heater downhole via the tubular body to a downhole target region that is proximal to the annular seal;   positioning a deflector in the downhole target region so that the deflector is up-hole of the annular seal and down-hole of a portion of the tubular body wall that comprises one or more openings;   delivering alloy beads to the downhole target region via the tubular body such that the deflector redirects the alloy beads radially outwards towards said one or more openings and into the annulus, wherein the alloy beads accumulate on top of the annular seal; and   operating said heating tool to increase the temperature within the downhole target region to a temperature that is sufficient to melt the alloy beads accumulated within the annulus before allowing the molten alloy to cool and form an alloy plug that repairs the leaking annular seal.   
     
     
         2 . The method of  claim 1 , wherein the annular seal comprises a cement seal and/or an annular packer. 
     
     
         3 . The method of  claim 1 , wherein said heating tool is deployed to a location within the wellbore tubular body that is proximal to and up-hole of the annular seal. 
     
     
         4 . The method of  claim 1  or  2 , wherein the heating tool comprises multiple heaters that are operated independently to provide heat at different times. 
     
     
         5 . The method of  claim 4 , wherein said heaters are independently operated to:
 a) commence generating heat before the heating tool reaches the downhole target region;   b) pre-heat the alloy beads before they are redirected into the annulus by the deflector;   c) pre-heat the downhole target region before the alloy beads are accumulated on top of the annular seal;   d) provide the alloy melting temperature within the downhole target region after the alloy beads have begun to accumulate on top of the annular seal; and/or   e) provide the alloy melting temperature within the downhole target region once the alloy beads have accumulated on top of the annular seal.   
     
     
         6 . The method of any one of  claims 1  to  5 , wherein the heating tool and the deflector are provided as an annular seal repair tool assembly that is deployed downhole via a common delivery support that is connected to delivery means located above-ground at the surface of the wellbore. 
     
     
         7 . The method of  claim 6 , wherein the common delivery support used to deploy the annular seal repair tool assembly downhole is selected from: coiled tubing, pipe, slick line and wireline. 
     
     
         8 . The method of any one of  claims 1  to  7 , wherein the delivery of the alloy beads is achieved by dumping the alloy beads into the wellbore tubular body from a location above-ground at the surface of the wellbore. 
     
     
         9 . The method of  claim 6  or  7 , wherein the delivery of the alloy beads is achieved by a dump bailer deployed downhole via the tubular body, said dump bailer forming part of the annular seal repair tool assembly. 
     
     
         10 . The method of  claim 6  or  7 , wherein the delivery of the alloy beads is achieved via the coiled tubing or pipe that is used to deploy the annular seal repair tool assembly downhole. 
     
     
         11 . The method of any one of the preceding claims, further comprising forming one or more openings in the portion of the tubular body wall that is located up-hole from the annular seal, wherein said one or more openings are formed prior to the delivery of the alloy beads using a hole making tool that forms part of the annular seal repair tool assembly. 
     
     
         12 . The method of any one of the preceding claims, wherein the downhole target region is agitated in order to assist the passage of the alloy beads through said one or more openings into the annulus. 
     
     
         13 . The method of  claim 12 , wherein the deflector is vibrated to agitate the downhole target region. 
     
     
         14 . The method of  claim 12  or  13 , wherein the tubular body is vibrated to agitate the downhole target region. 
     
     
         15 . The method of any one of the preceding claims, wherein the deflector comprises insulating means configured to restrict the passage of conducted heat through the deflector. 
     
     
         16 . The method of any one of the preceding claims, wherein the deflector is deployed downhole in an unexpanded or partially expanded state and then expanded towards the tubular body wall in the downhole target region so as to increase the extent to which the deflector redirects the alloy beads. 
     
     
         17 . The method of any one of the preceding claims, wherein the heating tool comprises one or more chemical reaction heaters. 
     
     
         18 . The method of any one of the preceding claims, wherein the alloy beads are provided in the form of a low melting alloy that has melting point of less than 300° C. 
     
     
         19 . The method of any one of the preceding claims, wherein the alloy beads are provided in the form of a bismuth based alloy. 
     
     
         20 . A downhole annular seal repair tool assembly for use in forming an alloy plug on an existing annular seal that substantially encircles an oil/gas wellbore tubular body, said assembly comprising:
 a delivery support connection point, by which the assembly is connectable to delivery means via a delivery support such that the assembly can be delivered to and retrieved from a downhole target region of the wellbore via the tubular body;   a heating tool having at least one heater, said heating tool configured to increase the temperature within the downhole target region to temperature that is sufficient to melt alloy beads accumulated within the annulus so as to enable the formation of the alloy plug on the existing annular seal; and   a deflector arranged up-hole of said heating tool, wherein the deflector is configured to obstruct alloy beads delivered downhole and redirect them radially outwards towards the walls of the wellbore tubular body.   
     
     
         21 . The assembly of  claim 20 , wherein the heating tool comprises multiple heaters that are independently controlled. 
     
     
         22 . The assembly of  claim 20  or  21 , wherein the deflector comprises an up-hole facing surface that comprises at least one sloped region. 
     
     
         23 . The assembly of  claim 22 , wherein the up-hole facing surface of the deflector is cone shaped and preferably the apex of the cone is located at the central axis of the deflector. 
     
     
         24 . The assembly of any one of  claims 20  to  23 , further comprising an agitation mechanism configured to agitate and/or vibrate the downhole target region of the wellbore. 
     
     
         25 . The assembly of any one of  claims 20  to  24 , wherein the agitation mechanism is configured to vibrate the deflector. 
     
     
         26 . The assembly of any one of  claims 20  to  25 , wherein the agitation mechanism is configured to vibrate the tubular body within the downhole target region of the wellbore. 
     
     
         27 . The assembly of any one of  claims 20  to  26 , wherein the deflector is configured to be expandable radially outwards towards the tubular body wall. 
     
     
         28 . The assembly of  claim 27 , wherein the mechanism by which the expansion of the deflector is achieved is selected from hydraulic means, pneumatic means, mechanical means and combinations thereof. 
     
     
         29 . The assembly of  claim 27  or  28 , wherein the deflector is urged to expand and/or contract by way of one or more resilient biasing means. 
     
     
         30 . The assembly of  claim 29 , wherein the deflector comprises a canopy of flexible material connected to an umbrella spring mechanism. 
     
     
         31 . The assembly of any one of  claims 20  to  30 , wherein the deflector comprises insulating means configured to restrict the passage of conducted heat through the deflector. 
     
     
         32 . The assembly of any one of  claims 20  to  31 , further comprising a delivery support selected from: coiled tubing, pipe, slick line and wireline. 
     
     
         33 . The assembly of  claim 32 , wherein the delivery support is either coiled tubing or pipe and such are configured to deliver alloy beads to the downhole target region of the wellbore. 
     
     
         34 . The assembly of any one of  claims 20  to  32 , further comprising alloy bead delivery means in the form of a dump bailer arranged up-hole of the deflector and said heating tool. 
     
     
         35 . The assembly of any one of  claims 20  to  34 , further comprising hole making equipment configured to form one or more opening in the walls of the wellbore tubular body. 
     
     
         36 . The assembly of  claim 35 , wherein the hole making equipment is selected from: a drill, a mechanical punch, a perforating gun, a saw or any other suitable cutting tools such as chemical cutters and fluid jet cutters. 
     
     
         37 . The assembly of any one of  claims 20  to  36 , further comprising a junk basket positioned at a leading end of the assembly. 
     
     
         38 . The assembly of any one of  claims 20  to  37 , wherein the heating tool comprises one or more chemical reaction heaters.