Method and composition to increase viscosity of crosslinked polymer fluids

Abstract

The invention discloses a well treatment composition for use in a subterranean formation comprising: a carrier fluid; and a viscoelastic surfactant being present in a concentration of less than about 1.5% by weight. Optionally, the fluid comprises a crosslinked polymer in a thickening amount in the carrier fluid. The invention also discloses a method to increase the viscosity of a fluid, the method comprising: providing a fluid comprising a thickening amount of a crosslinked polymer; adding a viscoelastic surfactant at a given concentration to the fluid; taking the fluid to a given temperature; defining a viscosity profile of the fluid depending of the concentration and the temperature; comparing said viscosity profile to a viscosity profile of the crosslinked polymer fluid alone; and defining an optimum concentration of the viscoelastic surfactant for each temperature.

1 . A well treatment composition for use in a subterranean formation comprising: a carrier fluid and a viscoelastic surfactant present in a concentration of less than about 1.5% by weight. 
     
     
         2 . The composition of  claim 1 , further comprising a crosslinked polymer in a thickening amount in the carrier fluid. 
     
     
         3 . The composition of  claim 1 , wherein the viscoelastic surfactant is present in a concentration of less than about 1% by weight. 
     
     
         4 . The composition of  claim 1 , wherein the viscoelastic surfactant is present in a concentration of less than about 0.8% by weight. 
     
     
         5 . The composition of  claim 1 , wherein the crosslinked polymer is taken in the group consisting of: polysaccharides, substituted galactomannans, guar gums, high-molecular weight polysaccharides composed of mannose and galactose sugars, guar derivatives, hydroxypropyl guar (HPG), carboxymethylhydroxypropyl guar (CMHPG), carboxymethyl guar (CMG), hydrophobically modified guars, guar-containing compounds, synthetic polymers and mixtures thereof. 
     
     
         6 . The composition of  claim 1 , further comprising a co-surfactant. 
     
     
         7 . The composition of  claim 1 , wherein the viscoelastic surfactant is a zwitterionic surfactant. 
     
     
         8 . The composition of  claim 7 , wherein the viscoelastic surfactant is betaine. 
     
     
         9 . The composition of  claim 1 , wherein the carrier fluid is aqueous based fluid. 
     
     
         10 . A method of treating a subterranean formation from a well, the method comprising:
 a. providing a carrier fluid comprising a viscoelastic surfactant in a concentration of less than about 1.5% by weight; and   b. introducing the fluid into the well.   
     
     
         11 . The method of  claim 10 , wherein the fluid further comprises a thickening amount of a crosslinked polymer. 
     
     
         12 . The method of  claim 10 , further comprising contacting the fluid and the subterranean formation. 
     
     
         13 . The method of  claim 12 , further comprising fracturing the subterranean formation. 
     
     
         14 . The method of  claim 10 , wherein the fluid further comprises proppant. 
     
     
         15 . The method of  claim 10 , wherein the viscoelastic surfactant is present in a concentration of less than about 1% by weight. 
     
     
         16 . The method of  claim 10 , wherein the viscoelastic surfactant is present in a concentration of less than about 0.8% by weight. 
     
     
         17 . The method of  claim 10 , wherein the crosslinked polymer is taken in the group consisting of: polysaccharides, substituted galactomannans, guar gums, high-molecular weight polysaccharides composed of mannose and galactose sugars, guar derivatives, hydroxypropyl guar (HPG), carboxymethylhydroxypropyl guar (CMHPG), carboxymethyl guar (CMG), hydrophobically modified guars, guar-containing compounds, synthetic polymers and mixtures thereof. 
     
     
         18 . The method of  claim 10 , wherein the viscoelastic surfactant is betaine. 
     
     
         19 . The method of  claim 10 , wherein the carrier fluid is water. 
     
     
         20 . A method to increase the viscosity of a fluid, the method comprising:
 a. providing a fluid comprising a thickening amount of a crosslinked polymer;   b. adding a viscoelastic surfactant at a given concentration to the fluid;   c. taking the fluid to a given temperature;   d. defining a viscosity profile of the fluid depending of the concentration and the temperature;   e. comparing said viscosity profile to a viscosity profile of the crosslinked polymer fluid alone; and   f. defining an optimum concentration of the viscoelastic surfactant for each temperature.   
     
     
         21 . The method of  claim 20 , wherein the given temperature is between 45 degC and 95 degC. 
     
     
         22 . The method of  claim 20 , wherein the crosslinked polymer is taken in the group consisting of: polysaccharides, substituted galactomannans, guar gums, high-molecular weight polysaccharides composed of mannose and galactose sugars, guar derivatives, hydroxypropyl guar (HPG), carboxymethylhydroxypropyl guar (CMHPG), carboxymethyl guar (CMG), hydrophobically modified guars, guar-containing compounds, synthetic polymers and mixtures thereof. 
     
     
         23 . The method of  claim 20 , wherein the viscoelastic surfactant is zwitterionic surfactant. 
     
     
         24 . The method of  claim 23 , wherein the viscoelastic surfactant is betaine.