Viscoelastic Surfactant Fluids and Related Methods of Use

Abstract

Viscoelastic surfactant based aqueous fluid systems useful as thickening agents in various applications, e.g. to suspend particles produced during the excavation of geologic formations. The surfactants are zwitterionic/amphoteric surfactants such as dihydroxyl alkyl glycinate, alkyl ampho acetate or propionate, alkyl betaine, alkyl amidopropyl betaine and alkylimino mono- or di-propionates derived from certain waxes, fats and oils. The thickening agent is used in conjunction with an inorganic water-soluble salt or organic additive such as phthalic acid, salicylic acid or their salts.

1 - 148 . (canceled)  
     
     
         149 . A method of fracturing a subterranean formation comprising the step of pumping a viscoelastic fluid through a wellbore and into a subterranean formation at a pressure sufficient to fracture the formation, wherein said viscoelastic fluid comprises: 
 a) an aqueous medium;    b) a zwitterionic surfactant represented by the formula (I):                           or the formula (II):                           wherein R 1 , represents a hydrophobic moiety of alkyl, alkylarylalkyl, alkoxyalkyl, alkylaminoalkyl and alkylamidoalkyl, wherein alkyl represents a group that contains from about 16 to about 22 carbon atoms, which may be branched or straight chained and which may be saturated or unsaturated, and wherein said alkylene groups have from about 1 to about 6 carbon atoms; R 2  and R 3  are independently aliphatic chains having from about 1 to about 30 carbon atoms, and R 4  is a hydrocarbyl radical with a chain length of about 1 to about 4;    c) a member selected from the group consisting of organic acids, organic acid salts, inorganic salts, and combinations of one or more organic acids or organic acid salts with one or more inorganic salts; and    d) an additive selected from the group consisting of corrosion inhibitors and fluid-loss additives and mixtures thereof.    
     
     
         150 . The method of  claim 149  wherein the amount of said surfactant is from about 0.5% to about 6% by weight of said fluid.  
     
     
         151 . The method of  claim 149  wherein R 2  and R 3  are independently alkyl, alkenyl, arylalkyl, hydroxyalkyl, carboxyalkyl, or hydroxyalkyl-polyoxyalkylene, each having from about 1 to about 10 carbon atoms and preferably are methyl, ethyl, benzyl, hydroxyethyl, hydroxypropyl, carboxymethyl, or carboxyethyl.  
     
     
         152 . The method of  claim 151  wherein said alkyl represents a group selected from oleyl, octadecyl, erucyl, and the derivatives of tallow, coco, soya and rapeseed oils.  
     
     
         153 . The method of  claim 151  wherein R 1  is RCONHCH 2 CH 2 CH 2 — wherein R is an alkyl group containing from about 16 to about 22 carbon atoms which may be branched or straight chained and which may be saturated or unsaturated and R 2  and R 3  are each beta-hydroxyethyl.  
     
     
         154 . The method of  claim 151  wherein R 2  is beta-carboxyethyl and R 4  is ethylene.  
     
     
         155 . The method of  claim 151  wherein said surfactant is an alkenylamidoalkyl betaine.  
     
     
         156 . The method of  claim 149  wherein said surfactant is oleamidopropyl betaine.  
     
     
         157 . The method of  claim 149  wherein said member comprises an aromatic moiety selected from the group consisting of sulfonic moieties, sulfonate moieties, carboxylic moieties, and carboxylate moieties.  
     
     
         158 . The method as claimed in  claim 157  wherein said aromatic moiety is selected from the group consisting of salicylate ions and phthalate ions, hydroxynaphthalene carboxylate ions, and mixtures thereof.  
     
     
         159 . The method of  claim 149  wherein said member is present in an amount of from about 0.1% to about 30% by weight, preferably in an amount of from about 0.1% to about 8% by weight.  
     
     
         160 . The method of  claim 149  wherein said viscoelastic fluid further comprises a particulate proppant suspended therein.  
     
     
         161 . The method of  claim 149  wherein the fluid comprises from about 0.5% to about 6% of the surfactant and from about 0.1% to about 6% of a combination of a member selected from the group consisting of p-toluene sulfonate, naphthalene sulfonate, chlorobenzoic acid, salicylic acid and phthalic acid, with a member comprising one or more water-soluble ammonium salts.  
     
     
         162 . The method of  claim 149  wherein the fluid comprises from about 2% to about 5% of the surfactant.  
     
     
         163 . The method of  claim 149  wherein the fluid comprises from about 3% to about 5% of the surfactant  
     
     
         164 . The method of  claim 149  wherein the fluid comprises from about 0.5% to about 6% of the surfactant and from about 0.1% to about 6% of a combination of a member selected from the group consisting of p-toluene sulfonate, naphthalene sulfonate, chlorobenzoic acid, salicylic acid and phthalic acid, with a member comprising one or more water-soluble salts.  
     
     
         165 . A method according to  claim 149  wherein said alcohol ethoxylate is an alkanol ethoxylate.  
     
     
         166 . A method according to  claim 149  wherein said additive is a corrosion inhibitor.  
     
     
         167 . A method according to  claim 149  wherein said fluid further comprises a polyacrylate.  
     
     
         168 . A method of fracturing a subterranean formation comprising the step of pumping a viscoelastic fluid through a wellbore and into a subterranean formation at a pressure sufficient to fracture the formation, wherein said viscoelastic fluid comprises: 
 a) an aqueous medium;    b) a surfactant selected from the group consisting of amphoteric surfactants, zwitterionic surfactants, and mixtures thereof;    c) an alcohol selected from medium to long chain alcohols; and    d) an additive selected from the group consisting of corrosion inhibitors and fluid-loss additives and mixtures thereof.    
     
     
         169 . A method according to  claim 168  wherein said medium to long chain alcohol is an alkanol.  
     
     
         170 . A method according to  claim 169  wherein said alkanol has from about five to about ten carbon atoms.  
     
     
         171 . A method according to  claim 168  wherein said medium to long chain alcohol is an alcohol ethoxylate.  
     
     
         172 . A method according to  claim 171  wherein said alcohol ethoxylate is an ethoxylate of a 12 to 16 carbon alcohol.  
     
     
         173 . A method according to  claim 171  wherein said alcohol ethoxylate contains from 1 to 6 oxyethylene units.  
     
     
         174 . A method according to  claim 171  wherein said alcohol ethoxylate contains from 1 to 4 oxyethylene units.  
     
     
         175 . A method according to  claim 171  wherein said alcohol ethoxylate is an alkanol ethoxylate.  
     
     
         176 . A method according to  claim 168  wherein said fluid further contains a corrosion inhibitor.  
     
     
         177 . A method according to  claim 168  wherein said viscoelastic fluid is foamed or energized by the addition of air, nitrogen or carbon dioxide.  
     
     
         178 . The method of  claim 168  wherein said surfactant is a zwitterionic surfactant comprising a quaternary ammonium hydrophilic moiety covalently bonded with an alkyl or a hydroxyalkyl group.  
     
     
         179 . The method of  claim 168  wherein said surfactant is represented by the formula (I):  
       
         
           
           
               
               
           
         
       
       or the formula (II):  
       
         
           
           
               
               
           
         
       
       wherein R 1 , represents alkyl, alkenyl, alkylarylalkylene, alkenylarylalkylene, alkylaminoalkylene, alkenylaminoalkylene, alkylamidoalkylene, or alkenylamidoalkylene, wherein each of said alkyl groups contains from about 16 to about 22 carbon atoms and may be branched or straight chained and saturated or unsaturated, and wherein said alkylene groups have from about 1 to about 6 carbon atoms; R 2  and R 3  are independently aliphatic chains having from about 1 to about 30 carbon atoms, and R 4  is a hydrocarbyl radical with a chain length of about 1 to about 4.  
     
     
         180 . The method of  claim 179  wherein said surfactant is an alkenylamidoalkyl betaine.  
     
     
         181 . The method of  claim 168  wherein said surfactant is oleamidopropyl betaine.  
     
     
         182 . A method according to  claim 168  wherein said fluid further comprises a polyacrylate.  
     
     
         183 . The method of  claim 168  wherein said viscoelastic fluid further comprises a particulate proppant suspended therein.  
     
     
         184 . A method of enhanced oil recovery from a subterranean formation, comprising injecting into the formation through a wellbore intersecting the formation a fluid comprising: 
 a. a thickener comprising a surfactant selected from amphoteric, zwitterionic and mixtures thereof,    b. an aqueous medium,    c. a member selected from the group consisting of organic acids, organic acid salts, inorganic salts, and combinations of one or more organic acids or organic acid salts with one or more inorganic salts.    
     
     
         185 . A method of enhanced oil recovery according to  claim 184  wherein said fluid further comprises an additive selected from the group consisting of corrosion inhibitors and fluid loss agents.  
     
     
         186 . A method according to  claim 184  wherein said additive is a corrosion inhibitor.  
     
     
         187 . The method of  claim 184  wherein the amount of said surfactant is from about 0.5% to about 6% by weight of said fluid.  
     
     
         188 . The method of  claim 184  wherein the surfactant is a zwitterionic surfactant represented by the formula (I):  
       
         
           
           
               
               
           
         
       
       or the formula (II):  
       
         
           
           
               
               
           
         
       
       wherein R 1 , represents a hydrophobic moiety of alkyl, alkylarylalkyl, alkoxyalkyl, alkylaminoalkyl and alkylamidoalkyl, wherein alkyl represents a group that contains from about 16 to about 22 carbon atoms, which may be branched or straight chained and which may be saturated or unsaturated, and wherein said alkylene groups have from about 1 to about 6 carbon atoms; R 2  and R 3  are independently aliphatic chains having from about 1 to about 30 carbon atoms, and R 4  is a hydrocarbyl radical with a chain length of about 1 to about 4;  
     
     
         189 . The method of  claim 188  wherein R 2  and R 3  are independently alkyl, alkenyl, arylalkyl, hydroxyalkyl, carboxyalkyl, or hydroxyalkyl-polyoxyalkylene, each having from about 1 to about 10 carbon atoms and preferably are methyl, ethyl, benzyl, hydroxyethyl, hydroxypropyl, carboxymethyl, or carboxyethyl.  
     
     
         190 . The method of  claim 188  wherein said alkyl represents a group selected from oleyl, octadecyl, erucyl, and the derivatives of tallow, coco, soya and rapeseed oils.  
     
     
         191 . The method of  claim 188  wherein R 1 , is RCONHCH 2 CH 2 CH 2 — wherein R is an alkyl group containing from about 16 to about 22 carbon atoms which may be branched or straight chained and which may be saturated or unsaturated and R 2  and R 3  are each beta-hydroxyethyl.  
     
     
         192 . The method of  claim 188  wherein R 2  is beta-carboxyethyl and R 4  is ethylene.  
     
     
         193 . The method of  claim 188  wherein said surfactant is an alkenylamidoalkyl betaine.  
     
     
         194 . The method of  claim 188  wherein said surfactant is oleamidopropyl betaine.  
     
     
         195 . The method of  claim 184  wherein said member comprises an aromatic moiety selected from the group consisting of sulfonic moieties, sulfonate moieties, carboxylic moieties, and carboxylate moieties.  
     
     
         196 . The method as claimed in  claim 194  wherein said aromatic moiety is selected from the group consisting of salicylate ions and phthalate ions, hydroxynaphthalene carboxylate ions, and mixtures thereof.  
     
     
         197 . The method of  claim 184  wherein said member is present in an amount of from about 0.1% to about 30% by weight, preferably in an amount of from about 0.1% to about 8% by weight.  
     
     
         198 . The method of  claim 184  wherein the fluid further comprises a particulate proppant suspended therein.  
     
     
         199 . The method of  claim 184  wherein the fluid comprises from about 0.5% to about 6% of the surfactant and from about 0.1% to about 6% of a combination of a member selected from the group consisting of p-toluene sulfonate, naphthalene sulfonate, chlorobenzoic acid, salicylic acid and phthalic acid, with a member comprising one or more water-soluble ammonium salts.  
     
     
         200 . The method of  claim 184  wherein the fluid comprises from about 2% to about 5% of the surfactant.  
     
     
         201 . The method of  claim 184  wherein the fluid comprises from about 3% to about 5% of the surfactant  
     
     
         202 . The method of  claim 184  wherein the fluid comprises from about 0.5% to about 6% of the surfactant and from about 0.1% to about 6% of a combination of a member selected from the group consisting of p-toluene sulfonate, naphthalene sulfonate, chlorobenzoic acid, salicylic acid and phthalic acid, with a member comprising one or more water-soluble salts.  
     
     
         203 . A method according to  claim 184  wherein said alcohol ethoxylate is an alkanol ethoxylate.  
     
     
         204 . A method according to  claim 184  wherein said fluid further comprises a polyacrylate.