Gaseous seal injection in a wellbore

Abstract

A method for treating a well includes flowing a sealant heated to a gaseous phase to cement disposed in an annulus of a wellbore, where the annulus is formed between a casing installed in the wellbore and a cylindrical wall radially outward of the casing. The cement includes a fluid loss opening formed over time. The method includes flowing the sealant in gaseous phase through the fluid loss opening in the cement of the annulus, and cooling the sealant in the gaseous phase into a phase transition of the sealant. The phase transition includes a deposition of the sealant from the gaseous phase to a solid phase or a condensation of the sealant from the gaseous phase to a liquid phase. Further, the sealant seals the fluid loss opening in response to cooling the sealant.

1 . A method for treating a well, the method comprising:
 injecting a sealant in a gaseous phase into cement that is within and that seals an annulus of a wellbore proximate to a wellhead of the wellbore, the annulus formed between a casing installed in the wellbore and a cylindrical wall radially outward of the casing, where the cement disposed in the annulus includes a fluid loss opening formed over time in the cement;   flowing the sealant in gaseous phase through the fluid loss opening in the cement of the annulus;   in response to flowing the sealant through the fluid loss opening, cooling the sealant in the gaseous phase into a phase transition of the sealant, the phase transition comprising at least one of a deposition of the sealant from the gaseous phase to a solid phase or a condensation of the sealant from the gaseous phase to a liquid phase; and   sealing the fluid loss opening with the sealant in response to cooling the sealant.   
     
     
         2 . The method of  claim 1 , comprising heating the sealant in a heating chamber and converting the sealant to the gaseous phase. 
     
     
         3 . The method of  claim 2 , wherein converting the sealant to the gaseous phase comprises at least one of a sublimation of the sealant from solid phase to gaseous phase or an evaporation of the sealant from liquid phase to gaseous phase. 
     
     
         4 . The method of  claim 2 , wherein the heating chamber comprises an electric heating chamber, and heating the sealant comprises heating the sealant in the electric heating chamber. 
     
     
         5 . The method of  claim 2 , further comprising purging the heating chamber using inert gas chambers fluidly connected to the heating chamber. 
     
     
         6 . The method of  claim 1 , wherein injecting the sealant into the cement disposed in the annulus of the wellbore comprises pumping the sealant into the cement with a compressor. 
     
     
         7 . The method of  claim 1 , wherein injecting the sealant into the cement disposed in the annulus of the wellbore comprises continuously flowing the sealant in the gaseous phase into the cement until a positive pressure test of the annulus occurs. 
     
     
         8 . The method of  claim 1 , wherein injecting the sealant into the cement comprises injecting the sealant in the gaseous phase downhole through the cement in the annulus from a tophole surface of the wellbore. 
     
     
         9 . The method of  claim 1 , wherein the fluid loss opening comprises a crack in the cement of the wellbore, and sealing the fluid loss opening with the sealant comprises pressure sealing the crack in the cement of the wellbore with the sealant. 
     
     
         10 . The method of  claim 1 , wherein the sealant in gaseous phase comprises an inert gas. 
     
     
         11 . A well treatment system for treating a well, the well treatment system comprising:
 a heating chamber fluidly connected to an annulus of a wellbore proximate to a wellhead of the wellbore, the annulus sealed by cement, the heating chamber to heat a sealant to a gaseous phase and provide the sealant in gaseous phase to the cement that is within and that seals the annulus;   the sealant in gaseous phase to engage a fluid loss opening in the cement and, upon cooling the sealant, transition phases from the gaseous phase to at least one of a liquid phase or a solid phase and plug the fluid loss opening; and   a gas compressor to flow the sealant in the gaseous phase from the heating chamber to the annulus of the wellbore.   
     
     
         12 . (canceled) 
     
     
         13 . The well treatment system of  claim 11 , wherein the wellhead comprises a casing spool flange to receive a flow of the sealant from the heating chamber and direct the flow of sealant into the annulus of the wellbore. 
     
     
         14 . The well treatment system of  claim 11 , where the fluid loss opening in the cement disposed in the annulus of the wellbore comprises a crack in the cement. 
     
     
         15 . The well treatment system of  claim 14 , where the crack in the cement of the annulus comprises a micro-crack in the cement. 
     
     
         16 . The well treatment system of  claim 11 , wherein the heating chamber comprises an electric heating chamber. 
     
     
         17 . The well treatment system of  claim 11 , comprising inert gas chambers fluidly connected to the heating chamber to purge the heating chamber. 
     
     
         18 . The well treatment system of  claim 11 , where the annulus is formed between a casing installed in the wellbore and a cylindrical wall radially outward of the casing. 
     
     
         19 . The well treatment system of  claim 18 , where the cylindrical wall comprises a second casing installed in the wellbore radially outward from the first-mentioned casing or an inner wall of the wellbore. 
     
     
         20 . A method for treating a well, comprising:
 heating a sealing composition in a heating chamber to a gaseous phase;   flowing the sealing composition in the gaseous phase from the heating chamber to an annulus of a wellbore formed between a casing installed in the wellbore and a cylindrical wall of the wellbore, the annulus sealed with cement disposed in the annulus, wherein the cement includes a fluid loss opening formed over time in the cement;   injecting the sealing composition in the gaseous phase into the cement and through a fluid loss opening in the cement disposed in the annulus;   cooling the sealing composition into a phase transition of the sealing composition, the phase transition comprising at least one of a deposition of the sealing composition from the gaseous phase to a solid phase or a condensation of the sealing composition from the gaseous phase to a liquid phase; and   in response to cooling the sealing composition into the phase transition of the sealing composition, sealing the fluid loss opening with the sealing composition.   
     
     
         21 - 23 . (canceled)