Solids suspension with nanoparticle-associated viscoelastic surfactant micellar fluids

Abstract

An aqueous, viscoelastic fluid gelled with a viscoelastic surfactant (VES) may suspend solids such as proppants, gravel, drilling debris, waste solids and the like with an effective amount of a nano-sized additive including, but not necessarily limited to alkali earth metal oxides, alkali earth metal hydroxides, alkali metal oxides, alkali metal hydroxides, transition metal oxides, transition metal hydroxides, post-transition metal oxides, and post-transition metal hydroxides. The additives may also reduce the amount of VES required to maintain a given viscosity. These viscoelastic surfactant gelled aqueous fluids may be used as treatment fluids for subterranean hydrocarbon formations, such as in hydraulic fracturing, gravel packing and the like. The magnesium oxide, zinc oxide or other nanometer scale-sized additives are at a scale that may provide unique particle charges that use chemisorption, crosslinking and/or other chemistries to associate the micelles and suspend the solids.

What is claimed is: 
     
         1 . A gelled aqueous fluid comprising:
 an aqueous base fluid;   a viscoelastic surfactant (VES) gelling agent;   a particulate additive having a mean particle size of from about 1 nm to about 500 nm or less, selected from the group consisting of alkali earth metal oxides, alkali earth metal hydroxides, alkali metal oxides, alkali metal hydroxides, transition metal oxides, post-transition metal oxides, and mixtures thereof, where the transition metal in the transition metal oxide is titanium, and where the post-transition metal in the post-transition metal oxide is selected from the group consisting of gallium, indium, thallium, lead and bismuth; and   solids selected from the group consisting of proppants, gravel, drilling debris, waste solids, and combinations thereof, and wherein the size of the solids ranges from about 100 mesh to about 8 mesh (about 150 to about 2,360 microns);   
       where the particulate additive is present in an amount effective to suspend the solids in the gelled aqueous fluid. 
     
     
         2 . The gelled aqueous fluid of  claim 1  where the aqueous base fluid is brine. 
     
     
         3 . The gelled aqueous fluid of  claim 1  where:
 the alkali earth metal is selected from the group consisting of magnesium, calcium, strontium, barium and mixtures thereof; and 
 the alkali metal is selected from the group consisting of lithium, sodium, potassium, and mixtures thereof. 
 
     
     
         4 . The gelled aqueous fluid of  claim 1  where the effective amount of the additive ranges from about 0.1 to about 50.0 pptg (about 0.01 to about 6 kg/1000 liters) based on the gelled aqueous fluid. 
     
     
         5 . The gelled aqueous fluid of  claim 1  where the solids range in size from about 100 mesh to about 8 mesh (about 150 to about 2,360 microns). 
     
     
         6 . The gelled aqueous fluid of  claim 1  where the solids loading is equal to or less than 20 lbs per gallon (2.4 kg/liter). 
     
     
         7 . A gelled aqueous fluid comprising:
 an aqueous brine base fluid;   a viscoelastic surfactant (VES) gelling agent; and   from about 0.1 to about 50.0 pptg (about 0.01 to about 6 kg/1000 liters) based on the gelled aqueous fluid of a particulate additive having a mean particle size of from about 1 nm to about 100 nm or less, selected from the group consisting of alkali earth metal oxides, alkali earth metal hydroxides, alkali metal oxides, alkali metal hydroxides, transition metal oxides, post-transition metal oxides, and mixtures thereof, where the transition metal in the transition metal oxide is titanium, and where the post-transition metal in the post-transition metal oxide is selected from the group consisting of gallium, indium, thallium, lead and bismuth; and   solids selected from the group consisting of proppants, gravel, drilling debris, waste solids, and combinations thereof, and wherein the size of the solids ranges from about 100 mesh to about 8 mesh (about 150 to about 2,360 microns).   
     
     
         8 . The gelled aqueous fluid of  claim 7  where:
 the alkali earth metal is selected from the group consisting of magnesium, calcium, strontium, barium and mixtures thereof; and 
 the alkali metal is selected from the group consisting of lithium, sodium, potassium, and mixtures thereof. 
 
     
     
         9 . The gelled aqueous fluid of  claim 7  where the solids range in size from about 100 mesh to about 8 mesh (about 150 to about 2,360 microns). 
     
     
         10 . The gelled aqueous fluid of  claim 7  where the solids loading is equal to or less than 20 lbs per gallon (2.4 kg/liter). 
     
     
         11 . A gelled aqueous fluid comprising:
 an aqueous brine base fluid;   a viscoelastic surfactant (VES) gelling agent; and   from about 0.1 to about 50.0 pptg (about 0.01 to about 6 kg/1000 liters) based on the gelled aqueous fluid of a particulate additive having a mean particle size of from about 1 nm to about 100 nm or less, selected from the group consisting of alkali earth metal oxides, alkali earth metal hydroxides, alkali metal oxides, alkali metal hydroxides, transition metal oxides, post-transition metal oxides, and mixtures thereof, where
 the alkali earth metal is selected from the group consisting of magnesium, calcium, strontium, barium and mixtures thereof; and 
 the alkali metal is selected from the group consisting of lithium, sodium, potassium, and mixtures thereof; 
 the transition metal in the transition metal oxide is titanium, and 
 the post-transition metal in the post-transition metal oxide is selected from the group consisting of gallium, indium, thallium, lead and bismuth; and 
   solids selected from the group consisting of proppants, gravel, drilling debris, waste solids, and combinations thereof, and wherein the size of the solids ranges from about 100 mesh to about 8 mesh (about 150 to about 2,360 microns), where the solids range in size from about 100 mesh to about 8 mesh (about 150 to about 2,360 microns).   
     
     
         12 . The gelled aqueous fluid of  claim 11  where the solids loading is equal to or less than 20 lbs per gallon (2.4 kg/liter).