Methods of preparing and using clean viscous well treating fluids and compositions

Abstract

The present invention provides methods of preparing and using viscous gelled well treating fluids devoid of insoluble gelling agent residue and compositions. A viscous gelled treating fluid composition devoid of insoluble gelling agent residue basically comprises water, a hydrated gelling agent and the water insoluble residue therefrom, a base for raising the pH of the water so that the water insoluble residue is dissolved therein, and additional water to lower the amount of the gelling agent in the treating fluid relative to the amount of water therein and to lower the pH thereof.

1 . A method of preparing a viscous gelled well treating fluid comprising of: 
 (a) mixing a gelling agent with water to thereby form a viscous gelled aqueous fluid containing hydrated gelling agent and water insoluble residue therefrom in an amount in the range of from about 10 to about 2000 pounds of said gelling agent per 1000 gallons of said water;    (b) mixing a base with said viscous aqueous fluid to thereby raise the pH of said fluid to in the range of from about 10 to 13 whereby said water insoluble residue in said fluid is at least partially dissolved therein; and then    (c) adding additional water to said viscous aqueous fluid in an amount to thereby lower the amount of said gelling agent in said viscous aqueous fluid relative to the amount of water therein to in the range of from about 10 to about 80 pounds per 1000 gallons of water and to lower the pH thereof to in the range of from about 2 to about 12.    
     
     
         2 . The method of  claim 1  wherein said gelling agent mixed with water in accordance with step (a) is dry particulate gelling agent.  
     
     
         3 . The method of  claim 1  wherein said gelling agent mixed with said water is in the form of a liquid gel concentrate.  
     
     
         4 . The method of  claim 1  wherein said water is selected from the group consisting of fresh water and salt water.  
     
     
         5 . The method of  claim 1  wherein said gelling agent is a polysaccharide selected from the group consisting of galactomannan gums and derivatives thereof and modified celluloses and derivatives thereof.  
     
     
         6 . The method of  claim 1  wherein said gelling agent is a galactomannan selected from the group consisting of guar, hydroxypropylguar, carboxymethylhydroxypropylguar, carboxymethylguar, hydroxyethylguar and carboxymethylhydroxyethylguar.  
     
     
         7 . The method of  claim 1  wherein said gelling agent is hydroxypropylguar.  
     
     
         8 . The method of  claim 1  wherein said gelling agent is a modified cellulose derivative selected from the group consisting of hydroxyethylcellulose, carboxymethylhydroxyethylcellulose and carboxymethylcellulose.  
     
     
         9 . The method of  claim 1  wherein said gelling agent is hydroxyethylcellulose.  
     
     
         10 . The method of  claim 1  wherein said base is selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide and calcium hydroxide.  
     
     
         11 . The method of  claim 1  wherein said base is sodium hydroxide.  
     
     
         12 . A method of treating a subterranean zone penetrated by a well bore comprising of: 
 (a) preparing or providing a viscous gelled treating fluid comprising water, a hydrated gelling agent and the water insoluble residue therefrom, a base for raising the pH of said water so that said water insoluble residue is at least partially dissolved therein, and additional water to lower the amount of said gelling agent in said treating fluid relative to the amount of water therein and to lower the pH thereof; and    (b) introducing said viscous gelled well treating fluid at least partially devoid of insoluble gelling agent residue into said subterranean zone.    
     
     
         13 . The method of  claim 12  wherein said water is selected from the group consisting of fresh water and salt water.  
     
     
         14 . The method of  claim 12  wherein said gelling agent is a polysaccharide selected from the group consisting of galactomannan gums and derivatives thereof and modified celluloses and derivatives thereof.  
     
     
         15 . The method of  claim 12  wherein said gelling agent is a galactomannan selected from the group consisting of guar, hydroxypropylguar, carboxymethylhydroxypropylguar, carboxymethylguar, hydroxyethylguar and carboxymethylhydroxyethylguar.  
     
     
         16 . The method of  claim 12  wherein said gelling agent is hydroxypropylguar.  
     
     
         17 . The method of  claim 12  wherein said gelling agent is a modified cellulose derivative selected from the group consisting of hydroxyethylcellulose, carboxymethylhydroxyethylcellulose and carboxymethylcellulose.  
     
     
         18 . The method of  claim 12  wherein said gelling agent is hydroxyethylcellulose.  
     
     
         19 . The method of  claim 12  wherein said hydrated gelling agent and said insoluble residue produced therefrom is present in said water in an amount in the range of from about 10 to about 2000 pounds per 1000 gallons thereof.  
     
     
         20 . The method of  claim 12  wherein said base is selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide and calcium hydroxide.  
     
     
         21 . The method of  claim 12  wherein said base is sodium hydroxide.  
     
     
         22 . The method of  claim 12  wherein said base is present in said viscous gelled treating fluid in an amount sufficient to raise the pH of said treating fluid to in the range of from about 10 to 13.  
     
     
         23 . The method of  claim 12  wherein said additional water is present in said viscous gelled treating fluid in an amount sufficient to lower the amount of said gelling agent therein to in the range of from about 10 to about 80 pounds per 1000 gallons of water and to lower the pH thereof to in the range of from about 2 to about 12.  
     
     
         24 . A viscous gelled treating fluid composition comprising of: 
 water;    a hydrated gelling agent and the water insoluble residue therefrom;    a base for raising the pH of said water so that said water insoluble residue is at least partially dissolved therein; and    additional water to lower the amount of said gelling agent in said treating fluid relative to the amount of water therein and to lower the pH thereof.    
     
     
         25 . The composition of  claim 24  wherein said water is selected from the group consisting of fresh water and salt water.  
     
     
         26 . The composition of  claim 24  wherein said gelling agent is a polysaccharide selected from the group consisting of galactomannan gums and derivatives thereof and modified celluloses and derivatives thereof.  
     
     
         27 . The composition of  claim 24  wherein said gelling agent is a galactomannan selected from the group consisting of guar, hydroxypropylguar, carboxymethylhydroxypropylguar, carboxymethylguar, hydroxyethylguar and carboxymethylhydroxyethylguar.  
     
     
         28 . The composition of  claim 24  wherein said gelling agent is hydroxypropylguar.  
     
     
         29 . The composition of  claim 24  wherein said gelling agent is a modified cellulose derivative selected from the group consisting of hydroxyethylcellulose, carboxymethylhydroxyethylcellulose and carboxymethylcellulose.  
     
     
         30 . The composition of  claim 24  wherein said gelling agent is hydroxyethylcellulose.  
     
     
         31 . The composition of  claim 24  wherein said hydrated gelling agent and said water insoluble residue therefrom is present is said treating fluid in an amount in the range of from about 10 to about 2000 pounds of said gelling agent per 1000 gallons of said water.  
     
     
         32 . The composition of  claim 24  wherein said base is selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide and calcium hydroxide.  
     
     
         33 . The composition of  claim 24  wherein said base is sodium hydroxide.  
     
     
         34 . The composition of  claim 24  wherein said base is present in said viscous gelled treating fluid in an amount sufficient to raise the pH of said treating fluid to in the range of from about 10 to 13.  
     
     
         35 . The composition of  claim 24  wherein said additional water is present in said viscous gelled treating fluid in an amount sufficient to lower the amount of said gelling agent therein to in the range of from about 10 to about 80 pounds per 1000 gallons of water and to lower the pH thereof to in the range of from about 2 to about 12.