Casing annulus leakage repair method and system

Abstract

A method for repairing a leak in a cement sheath of a casing of a well. A portion of the inner casing and the cement sheath is removed to create an opening that extends through the inner casing and the cement sheath. A tool is inserted within the inner casing to a location adjacent to the opening and one or more segments of a heat-deforming material that are part of the tool is heated to cause melting of the heat-deforming material. The tool is configured to direct the melted heat-deforming material radially outward into the opening. Once cooled, the heat-deforming material plugs the opening, thereby repairing the leak within the cement sheath.

What is claimed is: 
     
         1 . A method for repairing a leak in a casing of a well, wherein the casing comprises an inner casing and an outer casing with a first space formed therebetween, the method comprising:
 removing a portion of the inner casing to create an opening in the inner casing so that the first space is accessible;   inserting a tubular and an annular packer tool attached to the tubular to a location adjacent to the opening, wherein the annular packer tool surrounds the tubular and comprises one or more segments of heat-deforming material on an outer surface of the annular packer tool;   inserting a heater into the well and positioning the heater at a location that is internally within the tubular and is adjacent to the annular packer tool;   activating the heater to a temperature above an activation temperature of the one or more segments of heat-deforming material, thereby causing the heat-deforming material to melt, and wherein the melted heat-deforming material flows into the opening; and   reducing the temperature of the location adjacent to the annular packer tool to below the activation temperature of the heat-deforming material to cause the melted heat-deforming material to solidify within the opening and within the first space.   
     
     
         2 . The method of  claim 1 , wherein the step of removing the portion of the inner casing comprises using a underreamer device to create the opening in the inner casing and to make the first space accessible. 
     
     
         3 . The method of  claim 1 , wherein the opening comprises an annular-shaped opening that is formed through the inner casing and through the first space so as to reveal an inner surface of the outer casing. 
     
     
         4 . The method of  claim 1 , wherein the heater comprises an electric heater, an inductive heater, or a chemical heater. 
     
     
         5 . The method of  claim 1 , further comprising:
 locating the leak in the casing by identifying inflow and outflow positions of the leak in the casing.   
     
     
         6 . The method of  claim 5 , wherein the step of identifying the inflow and outflow positions is performed by an acoustic logging tool. 
     
     
         7 . The method of  claim 1 , further comprising:
 cleaning the opening to remove debris and excess cement that comes from a cement sheath that is disposed within the first space.   
     
     
         8 . The method of  claim 1 , wherein the inner casing and the outer casing are separated by a cement sheath, wherein the step removing a portion of the inner casing further comprises removing an adjacent portion of the cement sheath via underreaming such that the opening includes an area from which the portions of inner casing and cement sheath are removed. 
     
     
         9 . The method of  claim 1 , further comprising:
 tying the scab liner to a production liner or a wellhead of the well to secure the scab liner.   
     
     
         10 . The method of  claim 1 , wherein the heat-deforming material is a low melting point alloy. 
     
     
         11 . The method of  claim 10 , wherein the low melting point alloy is an alloy that comprises bismuth (Bi) and tin (Sn). 
     
     
         12 . The method of  claim 1 , wherein the step of inserting the heater into the well comprises:
 lowering the heater into the well on an electricline, and   positioning the heater at a predetermined location that is adjacent to the annular packer tool; and   
       wherein the method further comprises:
 deactivating and subsequently removing the heater from the location adjacent to the annular packer tool. 
 
     
     
         13 . The method of  claim 1 , wherein the annular packer tool further comprises metal portions having a higher melting point than the activation temperature of the heat-deforming material segments, and wherein the heater heats the location adjacent to the annular packer tool to a temperature above the activation temperature of the one or more segments of heat-deforming material but below a melting point of the metal portions. 
     
     
         14 . The method of  claim 13 , wherein heat from the heater passes through the scab liner to heat the heat-deforming material segments that are located radially outward of both the heater and the scab liner. 
     
     
         15 . The method of  claim 13 , wherein the heater heats the location adjacent to the annular packer tool to a temperature approximately 50° C. above a highest expected service temperature of the well. 
     
     
         16 . A method for repairing a leak in a cement sheath of a casing of a well, wherein the casing comprises an inner casing and an outer casing with the cement sheath formed therebetween, the method comprising:
 removing a portion of the inner casing and the cement sheath at a location above the leak to create an opening that extends through the inner casing and extends at least partially within the cement sheath, respectively;   inserting a tool within the inner casing to a location adjacent to the opening, the tool being positioned radially inward of the inner casing, cement sheath and outer casing, the tool including one or more segments of heat-deforming material disposed along an outer surface of the tool;   heating the one or more segments of the heat-deforming material to cause the one or more segments of the heat-deforming material to melt and wherein the tool is configured to direct the melted heat-deforming material radially outward into the opening; and   cooling the melted heat-deforming material while the heat-deforming material remains in place within the opening to cause the heat-deforming material to solidify and plug the opening, thereby repairing the leak within the cement sheath.   
     
     
         17 . The method of  claim 16 , wherein the tool comprises an annular packer tool that surrounds and is coupled to a scab liner, wherein the annular packer tool is located adjacent the opening and wherein the step of heating the one or more segments comprises:
 inserting a heater within the scab liner and activating the heater to cause heat to radiate through the scab liner to the one or more segments of the heat-deforming material to cause melting thereof, and   
       wherein the step of cooling the melted heat-deforming material results in the heat-deforming material solidifying between the scab liner and the outer casing within the opening, thereby bonding the scab liner to the outer casing. 
     
     
         18 . A system for repairing a leak in a casing of a well, wherein the casing comprises an inner casing and an outer casing, the system comprising:
 an underreamer configured to remove a portion of the inner casing at the location of the leak to create an annular-shaped opening in the inner casing;   a tubular and an annular packer tool attached to the tubular, wherein the tubular is positioned a location adjacent to the annular-shaped opening, and wherein the annular packer tool comprises one or more segments of heat-deforming material on its outer surface; and   a heater configured to heat the well at the location adjacent to the annular packer tool, to a temperature above an activation temperature of the one or more segments of heat-deforming material.   
     
     
         19 . The system of  claim 18 , further comprising:
 an acoustic logging tool is configured to identify inflow and outflow positions of the leak behind the inner casing to determine the location of the leak.   
     
     
         20 . The system of  claim 18 , wherein the inner casing and the outer casing are separated by a cement sheath, wherein the underreamer is further configured to remove a portion of the cement sheath. 
     
     
         21 . The system of  claim 18 , further comprising:
 a production liner attached to the inner casing of the well; and   at least one tie configured to fix the scab liner to the production liner.   
     
     
         22 . The system of  claim 18 , wherein the heat-deforming material of the annular packer tool is a low melting point alloy. 
     
     
         23 . The system of  claim 22 , wherein the low melting point alloy is an alloy that comprises bismuth (Bi) and tin (Sn). 
     
     
         24 . The system of  claim 18 , further comprising:
 an electricline wherein the heater is configured to be attached to the electricline and the electricline is configured to be selectively lowered into the well on the electricline and stopped at a predetermined location that is adjacent to the annular packer tool.   
     
     
         25 . The system of  claim 18 , wherein the annular packer tool further comprises:
 metal portions having a melting point that is higher than the activation temperature of the segments of heat-deforming material, and wherein the heater is configured to heat the location adjacent to the annular packer tool to a temperature above the activation temperature of the segments of heat-deforming material but below the melting point of the metal portions.   
     
     
         26 . The system of  claim 23 , wherein the heater is configured to heat the location adjacent to the annular packer tool to a temperature approximately 50° C. above a highest expected service temperature of the well.