Method to create a permanent plug by inducing movement in caprock

Abstract

A process is directed at plugging a wellbore, wherein the wellbore has a portion extending at least partially through a caprock composed of salt rock. The process includes applying a barrier in the wellbore at or above the caprock. Thereafter, the process includes a step of promoting creep such that the salt rock in the caprock creeps into the wellbore to create a salt-rock plug in the wellbore, and hence, closes off the portion of the wellbore above the salt-rock plug from fluid flow communication with the portion of the wellbore below the salt-rock plug.

What is claimed is: 
     
         1 . A process for plugging a wellbore having a portion extending at least partially through a caprock composed of salt rock, the process comprising:
 applying a barrier in the wellbore at or above the caprock; and   after applying the barrier, promoting creep such that the salt rock in the caprock creeps into the wellbore to create a salt-rock plug in the wellbore to seal across the entire wellbore, and hence, close off the portion of the wellbore above the salt-rock plug from fluid flow communication with the portion of the wellbore below the salt-rock plug.   
     
     
         2 . The process of  claim 1 , wherein creep is promoted by regulating the pressure or temperature below the barrier. 
     
     
         3 . The process of  claim 2 , wherein the pressure or temperature are regulated to maintain maximum possible differential stress in the caprock. 
     
     
         4 . The process of  claim 2 , wherein pressure or temperature is regulated by introducing a fluid into a portion of the wellbore extending through the caprock. 
     
     
         5 . The process of  claim 4 , further comprising a pipe through the barrier, and wherein the fluid is introduced through the pipe into the portion of the wellbore extending through the caprock. 
     
     
         6 . The process of  claim 5 , wherein pressure is regulated by changing the density or surface pressure of the fluid. 
     
     
         7 . The process of  claim 5 , wherein temperature is regulated by changing the temperature of the fluid. 
     
     
         8 . The process of  claim 1 , wherein after the step of promoting creep, the process further comprises placing a plug barrier throughout the borehole above the salt-rock plug created by the caprock. 
     
     
         9 . The process of  claim 1 , wherein prior to promoting creep, the process comprises introducing an upper foreign-material plug into the portion of the wellbore extending at least partially through the caprock, such that during the step of promoting creep, salt rock creeps radially inward and compress fits to the foreign-material plug. 
     
     
         10 . The process of  claim 9 , wherein the upper foreign-material plug comprises cement, resin or both. 
     
     
         11 . The process of  claim 1 , wherein prior to the promoting of creep, the process further comprising introducing a lower foreign-material wellbore plug into the wellbore in a portion of the wellbore below the caprock. 
     
     
         12 . The process of paragraph 11, wherein the lower foreign-material wellbore plug comprises cement, resin or both. 
     
     
         13 . A process for plugging a wellbore having a portion extending at least partially through a caprock composed of salt rock, the process comprising:
 introducing a lower foreign-material wellbore plug into the wellbore in a portion of the wellbore below the caprock, and wherein the lower wellbore foreign-material plug comprises cement, resin or both;   thereafter, applying a barrier in the wellbore at or above the caprock; and   after applying the barrier, promoting creep such that the salt rock in the caprock creeps into the wellbore to create a salt rock plug in the wellbore to seal across the entire wellbore, and hence, close off the portion of the wellbore above the salt-rock plug from fluid flow communication with the portion of the wellbore below the salt-rock plug.   
     
     
         14 . The process of  claim 13 , wherein creep is promoted by regulating the pressure or temperature below the barrier so as to maintain maximum possible differential stress in the caprock. 
     
     
         15 . The process of  claim 13 , wherein creep is promoted by regulating the pressure or temperature below the barrier, and wherein pressure or temperature is regulated by introducing a fluid into a portion of the wellbore extending through the caprock. 
     
     
         16 . The process of  claim 15 , further comprising inserting a pipe through the barrier, and wherein the fluid is introduced through the pipe into the portion of the wellbore extending through the caprock. 
     
     
         17 . The process of  claim 13 , wherein the step of promoting creep is continued until a complete wellbore closure occurs such that the caprock continuum is restored to the state prior to drilling of the wellbore. 
     
     
         18 . The process of  claim 13 , wherein after the step of promoting creep, the process further comprises placing a plug barrier above the salt-rock plug created by the caprock. 
     
     
         19 . The process of  claim 13 , wherein prior to promoting creep, the process comprises introducing an upper foreign-material plug into the portion of the wellbore extending at least partially through the caprock, such that during the step of promoting creep, salt rock creeps radially inward and compress fits to the foreign-material plug. 
     
     
         20 . The process of  claim 19 , wherein the upper foreign-material plug comprises cement, resin or both.