Gelled emulsions and methods of using the same

Abstract

Gelled emulsions contain (i.) an external phase of an aqueous water-soluble solvent solution, polymeric viscosifying agent and, optionally, an oxidative and/or acidic breaker; and (ii.) an internal phase of a dispersed organic fluid. The aqueous water-soluble solvent solution constitutes between from about 15 to about 50 volume percent of the gelled emulsion and the dispersed organic fluid is presented in the gelled emulsion in amounts ranging from about 50 to about 85 volume percent. The gelled emulsions are useful in a variety of applications including, but not limited to, oil field, pipeline and processing facility applications.

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         33 . A method of stimulating a subterranean formation which comprises introducing into the formation. an emulsion comprising:
 (a) a gelled external phase comprising (i.) an aqueous water-soluble solvent solution and (ii.) a polymeric viscosifying agent;   (b) an internal phase of an organic fluid;   (c) an emulsifying agent; and   (d) optionally, an oxidative and/or acidic breaker wherein the emulsion is substantially free of phosphorous.   
     
     
         34 . The method of  claim 33 , wherein the emulsion is prepared on the fly. 
     
     
         35 . The method of  claim 33 , wherein the emulsion contains no phosphorous. 
     
     
         36 . The method of  claim 33 , wherein the emulsion further comprises a proppant. 
     
     
         37 . The method of  claim 33 , wherein the emulsion further comprises a foaming or gasifying agent. 
     
     
         38 . The method of  claim 37 , wherein the foaming or gasifying agent is carbon dioxide or nitrogen. 
     
     
         39 . The method of  claim 33 , wherein the organic solvent of the organic solvent solution is selected from the group consisting of a C 1 -C 4  alcohol, ethylene glycol, propylene glycol, acetone, methylene sulfonic acid, acetic acid, formic acid and hydroxy acetic acid and mixtures thereof. 
     
     
         40 . The method of  claim 39 , wherein the organic solvent is a C 1 -C 4  alcohol. 
     
     
         41 . The method of  claim 40 , wherein the C 1 -C 4  alcohol is methanol, ethanol or isopropanol. 
     
     
         42 . The method of  claim 41 , wherein the C 1 -C 4  alcohol is methanol. 
     
     
         43 . The method of  claim 33 , wherein the emulsifying agent is at least one member selected from the group consisting of:
 (a) alkoxylated non-ionic emulsifiers having a lipophilic portion comprising a C 12 -C 36  alkyl, dialkyl or alkylaryl and a hydrophilic portion having 20 to 150 moles of polyalkylene oxide;   (b) an anionic, cationic or zwitterionic/amphoteric emulsifier having a lipophilic portion comprising a lipophilic portion comprising a C 12 -C 22  alkyl, dialkyl or alkylaryl group and a hydrophilic portion having 10 to 80 moles of polyalkylene oxide;   (c) an ethylene oxide/propylene oxide block copolymer comprising between from about 10 to about 50 moles of propylene oxide and from about 20 to about 150 moles of ethylene oxide; and   (d) polyoxyalkylene sorbitan fatty acid esters.   
     
     
         44 . The method of  claim 33 , wherein the emulsion contains an oxidative and/or acidic breaker and further wherein the oxidative and/or acidic breaker is selected from the group consisting of hydrochloric acid, formic acid, sulfamic acid, sodium bisulfate, an alkaline earth peroxide, an encapsulated persulfate, a catalyzed organic peroxide and a hydrochlorite bleach. 
     
     
         45 . The method of  claim 33 , wherein the organic fluid is at least one member selected from the group consisting of diesel, kerosene, gasoline, reformate, naphthalene, condensate, crude oil, mineral oil, vegetable oil, lubricating oil, synthetic oil, animal oil, an aliphatic, alicyclic or aromatic hydrocarbon, alkene, alkadienes and ester. 
     
     
         46 . The method of  claim 45 , wherein the organic fluid is selected from the group consisting of propane, n-butane, isobutane, n-hexane, n-octane, n-decane, n-tridecane, cyclohexane, benzene, toluene, xylene, ethylbenzene, naphthalene, a C 8 -C 15  alkane, an alkene and an alkadiene. 
     
     
         47 . The method of  claim 33 , wherein the polymeric viscosifying agent is selected from the group consisting of polysaccharides, polysaccharide derivatives containing monosaccharides, polyacrylates, polyacrylamides, acrylamide methyl propane sulfonic acid copolymers, polyvinyl alcohol, polyvinyl pyrrolidone, maleic anhydride methyl vinyl ether copolymers and polyethylene oxide. 
     
     
         48 . The method of  claim 47 , wherein the polymeric viscosifying agent is a polysaccharide or a derivatized polysaccharide of sugars selected from the group consisting of glucose, galactose, mannose, xylose, arabinose, fructose, guar gum derivatives, xanthan gum and a starch derivative. 
     
     
         49 . The method of  claim 48 , wherein the polymeric viscosifying agent is a guar derivative. 
     
     
         50 . The method of  claim 33 , wherein the polymeric viscosifying agent is selected from the group consisting of hydroxypropyl guar, hydroxyethyl guar, carboxymethyl hydroxypropyl guar, carboxymethyl hydroxyethyl cellulose and hydroxypropyl cellulose. 
     
     
         51 . The method of  claim 49 , wherein the guar derivative is a hydroxyalkylated guar or modified hydroxyalkylated guar. 
     
     
         52 . The method of  claim 51 , wherein the guar derivative is hydroxypropyl guar. 
     
     
         53 . The method of  claim 33 , wherein the HLB of the emulsifying agent is between from about 10 to about 20. 
     
     
         54 . The method of  claim 53 , wherein the HLB of the emulsifying agent is between from about 16 to about 18. 
     
     
         55 . The method of  claim 33 , wherein the relative solubility number of the emulsifying agent is in excess in 10. 
     
     
         56 . The method of  claim 55 , wherein the relative solubility number of the emulsifying agent is between from about 13 to about 17. 
     
     
         57 . A method of stimulating a subterranean formation which comprises introducing into the formation a gelled emulsion comprising:
 (a) from about 15 to about 50 volume percent of a blend of a C 1 -C 4  alkanol and water;   (b) from about 50 to about 85 volume percent of a dispersed organic fluid;   (c) a polymeric viscosifying agent;   (d) an emulsifying agent; and   (e) optionally, an oxidative and/or acidic breaker wherein the emulsion is substantially free of phosphorous.   
     
     
         58 . The method of  claim 57 , wherein the blend of C 1 -C 4  alkanol and water contains between from about 15 to about 80 volume percent of alkanol and the remainder water. 
     
     
         59 . The method of  claim 57 , wherein the alkanol is methanol. 
     
     
         60 . The method of  claim 57 , wherein the dispersed organic fluid is hydroxypropyl guar having a molar substitution between from about 0.80 to about 1.20. 
     
     
         61 . The method of  claim 57 , wherein the emulsifying agent is at least one member selected from the group consisting of:
 (a) alkoxylated non-ionic emulsifiers having a lipophilic portion comprising a C 12 -C 36  alkyl, dialkyl or alkylaryl and a hydrophilic portion having 20 to 150 moles of polyalkylene oxide;   (b) an anionic, cationic or zwitterionic/amphoteric emulsifier having a lipophilic portion comprising a lipophilic portion comprising a C 12 -C 22  alkyl, dialkyl or alkylaryl group and a hydrophilic portion having 10 to 80 moles of polyalkylene oxide;   (c) an ethylene oxide/propylene oxide block copolymer comprising between from about 10 to about 50 moles of propylene oxide and from about 20 to about 150 moles of ethylene oxide; and   (d) polyoxyalkylene sorbitan fatty acid esters.   
     
     
         62 . A method of stimulating a subterranean formation which comprises introducing into the formation an emulsion comprising:
 (a) an external phase comprising a gelled product of a (i) C 1 -C 4  alkanol and water; and (ii) a viscosifying polymer;   (b) an internal phase of a dispersed organic fluid; and   (c) an emulsifying agent.   
     
     
         63 . The method of  claim 62 , wherein the external phase further comprises an oxidative and/or acidic breaker. 
     
     
         64 . The method of  claim 62 , wherein the internal phase further comprises carbon dioxide.