Fracturing fluids containing borate esters as crosslinking agents

Abstract

A formation treating fluid comprises one or more borate esters, a liquid carrier and, one or more cross linkable polymer wherein the formation treating fluid has an alkaline pH when the formation treating fluid is positioned in a formation. The formation treating fluid is useful in high temperature operations such as hydraulic fracturing.

1 . A formation treating fluid including a cross linkable polymer and comprises, prior to the cross linkable polymer being cross linked: 
 a) a borate ester comprising a triester or a cyclic ester;    b) an organic solvent for the borate ester;    c) a liquid carrier; and,    d) the cross linkable polymer    wherein the formation treating fluid has an alkaline pH when the formation treating fluid is positioned in a formation.    
   
   
       2 . The formation treating fluid as claimed in  claim 1  further comprising a proppant.  
   
   
       3 . The formation treating fluid as claimed in  claim 1  further comprising a pH adjustment agent to raise the pH of the formation treating fluid to about 8 or higher.  
   
   
       4 . The formation treating fluid as claimed in  claim 3  wherein the pH is sufficiently low to prevent significant hydrolysis of the cross linkable polymer.  
   
   
       5 . The formation treating fluid as claimed in  claim 4  wherein the pH adjustment agent is an alkali or alkaline salt.  
   
   
       6 . The formation treating fluid as claimed in  claim 5  wherein the alkali or alkaline salt is one or more of an hydroxide, a carbonate, a bicarbonate and a silicate.  
   
   
       7 . The formation treating fluid as claimed in  claim 1  wherein the formation treating fluid has a pH from about 8 to about 13.  
   
   
       8 . The formation treating fluid as claimed in  claim 1  wherein the formation treating fluid has a pH from about 9.5 to about 11.5.  
   
   
       9 . The formation treating fluid as claimed in  claim 1  wherein the organic solvent is a cyclic organic compound.  
   
   
       10 . The formation treating fluid as claimed in  claim 1  wherein the borate ester comprises from about 0.001 to about 1 vol. % of the formation treating fluid.  
   
   
       11 . The formation treating fluid as claimed in  claim 1  wherein the borate ester comprises from about 0.005 to about 0.5 vol. % of the formation treating fluid.  
   
   
       12 . The formation treating fluid as claimed in  claim 1  wherein the borate ester comprises from about 0.01 to about 0.1 vol. % of the formation treating fluid.  
   
   
       13 . The formation treating fluid as claimed in  claim 1  wherein the liquid carrier comprises water, methanol or a mixture thereof.  
   
   
       14 . A formation treating fluid including a cross linkable polymer and comprises at the point of addition: 
 a) a borate ester in a cyclic organic solvent;    b) a liquid carrier; and,    c) the cross linkable polymer    wherein the formation treating fluid has an alkaline pH when the formation treating fluid is positioned in a formation.    
   
   
       15 . The formation treating fluid as claimed in  claim 14  further comprising a proppant.  
   
   
       16 . The formation treating fluid as claimed in  claim 14  further comprising a pH adjustment agent to raise the pH of the formation treating fluid to about 8 or higher.  
   
   
       17 . The formation treating fluid as claimed in  claim 16  wherein the pH is sufficiently low to prevent significant hydrolysis of the cross linkable polymer.  
   
   
       18 . The formation treating fluid as claimed in  claim 17  wherein the pH adjustment agent is an alkali or alkaline salt.  
   
   
       19 . The formation treating fluid as claimed in  claim 18  wherein the alkali or alkaline salt is one or more of an hydroxide, a carbonate, a bicarbonate and a silicate.  
   
   
       20 . The formation treating fluid as claimed in  claim 14  wherein the formation treating fluid has a pH from about 8 to about 13.  
   
   
       21 . The formation treating fluid as claimed in  claim 14  wherein the formation treating fluid has a pH from about 9.5 to about 11.5.  
   
   
       22 . The formation treating fluid as claimed in  claim 14  wherein the borate ester is one or more of a triester and a cyclic ester.  
   
   
       23 . The formation treating fluid as claimed in  claim 14  wherein the borate ester comprises from about 0.001 to about 1 vol. % of the formation treating fluid.  
   
   
       24 . The formation treating fluid as claimed in  claim 14  wherein the borate ester comprises from about 0.005 to about 0.5 vol. % of the formation treating fluid.  
   
   
       25 . The formation treating fluid as claimed in  claim 14  wherein the borate ester comprises from about 0.01 to about 0.1 vol. % of the formation treating fluid.  
   
   
       26 . The formation treating fluid as claimed in  claim 14  wherein the liquid carrier comprises water, methanol or a mixture thereof.