Low conductivity water based wellbore fluid

Abstract

A low electrical conductivity water-based wellbore fluid for use in drilling wells through a formation containing a clay which swells in the presence of water, said wellbore fluid that includes an aqueous base fluid; and a polymeric non-ionic tertiary amine is disclosed. Methods of using such fluids are also disclosed.

1 - 8 . (canceled) 
     
     
         9 . A method of reducing the swelling of clay in a well comprising:
 circulating in the well a water based wellbore fluid comprising:
 an aqueous base fluid; and 
 a polymeric non-ionic tertiary amine. 
   
     
     
         10 . The method of  claim 9 , wherein the polymeric non-ionic tertiary amine comprises a condensation reaction product of a tri-hydroxyalkyl amine. 
     
     
         11 . The method of  claim 10 , wherein the condensation reaction product has the general formula: 
       
         
           
           
               
               
           
         
         wherein each n is individually selected from the range from 1 to 3, and y ranges from 2 to 2000. 
       
     
     
         12 . The method of  claim 10 , wherein the tri-hydroxyalkyl amine is selected from the group consisting of trimethanolamine, triethanolamine or tripropanolamine. 
     
     
         13 . The method of  claim 9 , wherein the wellbore fluid has an electrical conductivity of less than about 10,000 μS/cm. 
     
     
         14 . The method of  claim 13 , wherein the wellbore fluid has an electrical conductivity of less than about 2000 μS/cm. 
     
     
         15 . The method of  claim 9 , further comprising:
 disposing of at least a portion of the wellbore fluid or cuttings on land.   
     
     
         16 . A method for controlling shale hydration in the drilling of subterranean wells comprising:
 adding to said well a water-based wellbore fluid comprising:
 an aqueous base fluid; and 
 a polymeric non-ionic tertiary amine. 
   
     
     
         17 . The method of  claim 16 , wherein the polymeric non-ionic tertiary amine comprises a condensation reaction product of a tri-hydroxyalkyl amine. 
     
     
         18 . The method of  claim 17 , wherein the condensation reaction product has the general formula: 
       
         
           
           
               
               
           
         
         wherein each n is individually selected from the range from 1 to 3, and y ranges from 2 to 2000. 
       
     
     
         19 . The method of  claim 17 , wherein the tri-hydroxyalkyl amine is selected from the group consisting of trimethanolamine, triethanolamine or tripropanolamine. 
     
     
         20 . The method of  claim 16 , wherein the wellbore fluid has an electrical conductivity of less than about 10,000 μS/cm. 
     
     
         21 . The method of  claim 20 , wherein the wellbore fluid has an electrical conductivity of less than about 2000 μS/cm.