Multi-trip annular seal repair method and associated equipment

Abstract

A multi-trip method of repairing a leaking annular seal located within an annulus that encircles an oil/gas 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. A heating tool is then operated to heat the alloy within the annulus to form an alloy plug above the annular seal. The present invention also provides various pieces of downhole equipment for use in the repair method of the 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:
 positioning a deflector in a downhole target region within the tubular body 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   providing a heating tool comprising at least one heater within the wellbore tubular body at a location proximal to the annular seal and operating the 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 a 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  or  2 , wherein the heating tool is provided at 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 said 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 the preceding claims, wherein the step of positioning the deflector in the downhole target region comprises deploying a bridge plug assembly within the wellbore tubular body, said bridge plug assembly being provided with the deflector on an up-hole face thereof. 
     
     
         7 . The method of  claim 6 , wherein the bridge plug assembly is deployed using a delivery support that is connected to delivery means located above-ground at the surface of the wellbore. 
     
     
         8 . The method of any one of the preceding claims, wherein the heating tool is deployed using a delivery support that is connected to delivery means located above-ground at the surface of the wellbore. 
     
     
         9 . The method of  claim 8 , wherein the heating tool further comprises a baffle configured to be positionable in the wellbore tubular body at a location between the heating tool and the delivery means, said baffle being configured to restrict the movement of heating fluids produced during the operation of the heating tool. 
     
     
         10 . The method of  claim 9 , wherein the baffle is employed as a deflector to redirect the alloy beads radially outwards towards said one or more openings and into the annulus. 
     
     
         11 . The method of  claim 7 ,  8 ,  9  or  10 , wherein the delivery support is selected from: coiled tubing, pipe, slick line and wireline. 
     
     
         12 . The method of any one of the preceding claims, wherein the delivery of the alloy beads is achieved by dumping the alloy beads into the wellbore tubular body from above-ground at the surface of the wellbore. 
     
     
         13 . The method of any one of  claims 1  to  11 , wherein the delivery of the alloy beads is achieved by a dump bailer deployed downhole via the tubular body. 
     
     
         14 . The method of  claim 13 , wherein the alloy is delivered from a dump bailer that forms part of the bridge plug assembly and/or the heating tool. 
     
     
         15 . The method of  claim 11 , wherein the delivery of the alloy beads is achieved via the coiled tubing or pipe that is used to deploy the bridge plug assembly and/or the heating tool. 
     
     
         16 . 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 above the downhole target region and the annular seal. 
     
     
         17 . The method of  claim 16 , wherein said one or more openings are formed using hole making equipment, 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 or fluid jet cutters. 
     
     
         18 . The method of  claim 16  or  17 , wherein said one or more openings are formed in the tubular body wall before the deflector is positioned within the downhole target region. 
     
     
         19 . 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. 
     
     
         20 . The method of  claim 19 , wherein the deflector is vibrated to agitate the downhole target region. 
     
     
         21 . The method of  claim 19  or  20 , wherein the agitation of the downhole target region is achieved by a motor assembly deployed downhole after the deflector has been positioned in the target region. 
     
     
         22 . The method of any one of  claims 19  to  21 , wherein the tubular body is vibrated to agitate the downhole target region. 
     
     
         23 . 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. 
     
     
         24 . The method of any one of the preceding claims, further comprising the intermediate step of retrieving the deflector after the alloy beads have been delivered but before the heating tool is provided within the tubular body and operated. 
     
     
         25 . The method of any one of the preceding claims, further comprising the step of deploying a junk basket downhole via the wellbore tubular body to a position that is down-hole of the downhole target region. 
     
     
         26 . The method of  claim 25 , wherein the junk basket is delivered downhole either in combination with the bridge plug assembly or the heating tool assembly or on its own. 
     
     
         27 . The method of any one of the preceding claims, wherein the heating tool comprises one or more chemical reaction heaters. 
     
     
         28 . 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. 
     
     
         29 . The method of any one of the preceding claims, wherein the alloy beads are provided in the form of bismuth based alloy. 
     
     
         30 . A bridge plug assembly for use in forming an alloy plug on an existing annular seal that encircles an oil/gas wellbore tubular body, said assembly comprising:
 a bridge plug operable to expand against and engage with the wellbore tubular body such that the bridge plug is retained in position within the wellbore tubular body; and   a deflector configured to obstruct alloy beads delivered downhole and redirect them radially outwards towards the tubular body wall, wherein the deflector is arranged up-hole of the bridge plug.   
     
     
         31 . The bridge plug assembly of  claim 30 , further comprising a delivery support connection point, by which the assembly is connectable to delivery means via a delivery support such that said assembly can be delivered to and retrieved from a downhole target region of a wellbore tubular body. 
     
     
         32 . The bridge plug assembly of  claim 31 , further comprising a delivery support connected to the delivery support connection point and wherein the deflector is located on the delivery support; wherein preferably the delivery support is selected from: coiled tubing, pipe, slick line and wireline. 
     
     
         33 . The bridge plug assembly of  claim 30 ,  31  or  32 , wherein the deflector comprises an up-hole facing surface that comprises at least one sloped region. 
     
     
         34 . The bridge plug assembly of  claim 30 ,  31 ,  32  or  33 , 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. 
     
     
         35 . The bridge plug assembly of any one of  claims 30  to  34 , wherein the deflector comprises an agitation mechanism configured to vibrate the deflector. 
     
     
         36 . The bridge plug assembly of any one of  claims 30  to  35 , wherein the deflector is configured to be expandable radially outwards towards the tubular body wall. 
     
     
         37 . The bridge plug assembly of  claim 36 , wherein the mechanism by which the expansion of the deflector is achieved is selected from hydraulic means, pneumatic means, mechanical means and combinations thereof. 
     
     
         38 . The assembly of  claim 36  or  37 , wherein the deflector is urged to expand and/or contract by way of one or more resilient biasing means. 
     
     
         39 . The downhole heater assembly of  claim 38 , wherein the deflector comprises a canopy of flexible material connected to an umbrella spring mechanism. 
     
     
         40 . The assembly of any one of  claims 30  to  39 , wherein the deflector comprises insulating means configured to restrict the passage of conducted heat through the deflector. 
     
     
         41 . A downhole heating assembly comprising:
 a heating tool with at least one heater;   a delivery support connection point, by which the heating tool is connectable to delivery means via a delivery support such that said heating assembly can be delivered to and retrieved from a downhole target region of a wellbore tubular body; and   a baffle configured to be positionable in the wellbore tubular body at a location between said heating tool and said delivery means, said baffle being configured to restrict the movement of heated fluids produced during the operation of the heating tool.   
     
     
         42 . The downhole heating assembly of  claim 41 , wherein the baffle is located between the heating tool and the delivery support connection point. 
     
     
         43 . The downhole heater assembly of  claim 41  or  42 , further comprising a delivery support connected to the delivery support connection point and wherein the baffle is located on the delivery support. 
     
     
         44 . The downhole heater assembly of  claim 43 , wherein the delivery support is selected from: coiled tubing, pipe, slick line and wireline. 
     
     
         45 . The downhole heater assembly of any one of  claims 41  to  44 , wherein the baffle is configured to be expandable towards the walls of a wellbore tubular body so as to increase the extent to which the baffle restricts fluid movement within the wellbore. 
     
     
         46 . The downhole heater assembly of  claim 45 , wherein the mechanism by which the expansion of the baffle is achieved is selected from hydraulic means, pneumatic means, mechanical means and combinations thereof. 
     
     
         47 . The downhole heater assembly of  claim 45  or  46 , wherein the assembly comprises control means that co-ordinate the operation of the heating tool and the expansion of the baffle. 
     
     
         48 . The downhole heater assembly of any one of  claim 45 ,  46 , or  47 , wherein the control means that control the expansion of the baffle are provided on the heating tool. 
     
     
         49 . The downhole heater assembly of any one of  claims 45  to  48 , wherein the baffle is urged to expand and/or contract by way of one or more resilient biasing means. 
     
     
         50 . The downhole heater assembly of  claim 49 , wherein the baffle comprises a canopy of flexible material connected to an umbrella spring mechanism. 
     
     
         51 . The downhole heater assembly of any one of  claims 41  to  50 , wherein the baffle is positioned a distance of up to 6 m (approx. 20 feet) from the heating tool, and preferably between 0.3 to 1.0 m (approx. 1 to 3 feet). 
     
     
         52 . The downhole heater assembly of any one of  claims 41  to  51 , wherein the heating tool comprises one or more chemical reaction heaters. 
     
     
         53 . The downhole heater assembly of any one of  claims 41  to  52 , the baffle comprises insulating means configured to restrict the passage of conducted heat through the baffle. 
     
     
         54 . The downhole heater assembly of any one of the  claims 41  to  53 , further comprising a junk basket positioned at the leading end of the assembly.