Compositions and methods for water shut-off in subterranean wells

Abstract

A fluid system and method to control downhole water problems in oilfield applications are provided. The system includes a sodium silicate solution and a hardener that is added just prior to pumping downhole in a single stage treatment. The hardener may be one or more esters such as dimethyl succinate, dimethyl glutarate, and/or dimethyl adipate. Permanent lost circulation control may be provided by the consequent silica gel formed. Once the treatment is placed, a specified amount of time can be adjusted to meet the needs of the well parameters.

We claim:  
     
         1 . A method for inhibiting the flow of water in a subterranean formation comprising: 
 injecting into the subterranean formation a composition comprising: 
 at least one hardener,  
 at least one catalyst,  
 at least one alkali metal silicate, and  
 water; and  
   permitting the composition to form silica gel in the subterranean formation for an effective period of time and of a sufficient gel strength to inhibit the flow of water in the formation.    
     
     
         2 . The method of  claim 1  where in the injecting, the hardener comprises at least one dialkyl ester of a dicarboxylic acid.  
     
     
         3 . The method of  claim 2  where in the injecting, the at least one dialkyl ester of a dicarboxylic acid has alkyl groups independently selected from straight or branched alkyl groups of 1 to 4 carbon atoms, and where the dicarboxylic acid used to make the ester has from 1 to 8 carbon atoms.  
     
     
         4 . The method of  claim 2  where in the injecting, the at least one dialkyl ester of a dicarboxylic acid is selected from the group consisting of dimethyl succinate, dimethyl glutarate, dimethyl adipate, and mixtures thereof.  
     
     
         5 . The method of  claim 1  where in the injecting, the catalyst is selected from the group consisting of an alkali metal hydroxide.  
     
     
         6 . The method of  claim 1  where in the injecting, the alkali metal silicate is sodium silicate.  
     
     
         7 . The method of  claim 1  where in the injecting, the hardener is added to the composition just before the injecting.  
     
     
         8 . The method of  claim 1  where in the injecting, the composition comprises from about 0.50 to about 2.50 v/v % hardener, from about 0.01 to about 5.00 wt % catalyst, from about 0.025 to about 10.00 v/v % alkali metal silicate, based on the total composition.  
     
     
         9 . A method for inhibiting the flow of water in a subterranean formation comprising: 
 injecting into the subterranean formation a composition comprising: 
 about 0.50 to about 2.50 v/v % of at least one hardener selected from the group consisting of dimethyl succinate, dimethyl glutarate, dimethyl adipate, and mixtures thereof,  
 about 0.01 to about 5.00 wt % of at least one catalyst selected from the group consisting of an alkali metal hydroxide,  
 about 0.025 to about 10.00 v/v % at least one alkali metal silicate, and  
 water; and  
   permitting the composition to form silica gel in the subterranean formation for an effective period of time and of a sufficient gel strength to inhibit the flow of water in the formation.    
     
     
         10 . The method of  claim 9  where in the injecting, the hardener is added to the composition just before the injecting.  
     
     
         11 . A composition for inhibiting the flow of water in a subterranean formation by formation of a silica gel, the composition comprising: 
 at least one hardener,    at least one catalyst,    at least one alkali metal silicate, and    water; and    
     
     
         12 . The composition of  claim 11  where the hardener comprises at least one dialkyl ester of a dicarboxylic acid.  
     
     
         13 . The composition of  claim 12  where the at least one dialkyl ester of a dicarboxylic acid has alkyl groups independently selected from straight or branched alkyl groups of 1 to 4 carbon atoms, and where the dicarboxylic acid used to make the ester has from 1 to 8 carbon atoms.  
     
     
         14 . The composition of  claim 12  where the at least one dialkyl ester of a dicarboxylic acid is selected from the group consisting of dimethyl succinate, dimethyl glutarate, dimethyl adipate, and mixtures thereof.  
     
     
         15 . The composition of  claim 11  where the catalyst is selected from the group consisting of an alkali metal hydroxide.  
     
     
         16 . The composition of  claim 11  where the alkali metal silicate is sodium silicate.  
     
     
         17 . The composition of  claim 11  where the composition comprises from about 0.5 to about 2.5 v/v % hardener, from about 0.01 to about 5.0 wt % catalyst, from about 0.025 to about 10.00 v/v % alkali metal silicate, based on the total composition.