Sealant for forming durable plugs in wells and methods for completing or abandoning wells

Abstract

Embodiments of the present invention generally relate to a sealant for forming durable plugs in wells and method for completing or abandoning wells. In one embodiment, a method of plugging a wellbore includes mixing sealant; mixing cement; pumping the cement and sealant into the wellbore. The cement is above the sealant and the sealant cures to become viscoelastic or semisolid.

1 . A method of completing or abandoning a wellbore, comprising:
 mixing sealant;   mixing cement;   pumping the cement and sealant into the wellbore, wherein:
 the cement is above the sealant, and 
 the sealant cures to become viscoelastic or semisolid. 
   
     
     
         2 . The method of  claim 1 , wherein the cement and sealant are pumped into a bore of a casing or liner. 
     
     
         3 . The method of  claim 2 , further comprising pumping the cement and sealant into an annulus formed between the casing or liner and the wellbore. 
     
     
         4 . The method of  claim 3 , further comprising perforating a wall of the casing or liner, wherein the cement and sealant are pumped through the perforations. 
     
     
         5 . The method of  claim 3 , further comprising section milling a window along the casing or liner, wherein the cement and sealant are pumped through the window. 
     
     
         6 . The method of  claim 3 , further comprising:
 setting a bridge plug in the casing bore; and   pumping the cement and sealant onto the bridge plug.   
     
     
         7 . The method of  claim 6 , further comprising cutting the casing string at or just below a seafloor. 
     
     
         8 . The method of  claim 2 , wherein the sealant is pumped in the annulus between two layers of cement. 
     
     
         9 . The method of  claim 1 , wherein the cement and sealant are pumped into an annulus formed between the casing or liner and the wellbore. 
     
     
         10 . The method of  claim 9 , wherein the sealant is pumped in the annulus between two layers of cement. 
     
     
         11 . The method of  claim 9 , further comprising deploying the casing or liner into the wellbore. 
     
     
         12 . The method of  claim 11 , further comprising drilling the wellbore. 
     
     
         13 . The method of  claim 1 , wherein the sealant cures to become a cross-linked polymer gel. 
     
     
         14 . The method of  claim 1 , wherein the gel cures to become an epoxy. 
     
     
         15 . The method of  claim 1 , wherein the sealant cures to become a composite comprising epoxy and a cross-linked polymer gel. 
     
     
         16 . The method of  claim 1 , wherein the sealant cures to become viscoelastic. 
     
     
         17 . A plug for completing or abandoning a wellbore, comprising:
 a top layer comprising Portland cement; and   a middle or bottom layer comprising a viscoelastic or semisolid sealant.   
     
     
         18 . The plug of  claim 17 , further comprising a bottom layer comprising Portland cement. 
     
     
         19 . A method for repairing damaged cement in a wellbore, comprising:
 forming an opening through a wall of a casing or liner cemented in the wellbore; and   pumping sealant through the opening and into the damaged cement,   wherein the sealant cures to become viscoelastic or semisolid.