Polyelectrolyte Complexes for Oil and Gas Applications

Abstract

A polyelectrolyte complex for the controlled release of an oil and gas field chemical selected from the group consisting of (a) a gel-forming or cross-linking agent, (b) a scale inhibitor, (c) a corrosion inhibitor, (d) an inhibitor of asphaltene or wax deposition, (e) a hydrogen sulfide scavenger, (f) a hydrate inhibitor, (g) a breaking agent, and a surfactant.

what is claimed and desired to be secured by Letters Patent is as follows: 
     
         1 . A method for controlling or delaying the release of a gel breaking agent in an oil and gas well comprising the steps of:
 providing a polyelectrolyte complex consisting essentially of a polyanion and a polycation, said polyelectrolyte complex entrapping or encapsulating said gel breaking agent, wherein said polyelectrolyte complex is a nanoparticle having a particle size less than about 2000 nm; and   introducing a composition comprising polyelectrolyte complex entrapping or encapsulating said gel breaking agent into an oil and gas well.   
     
     
         2 . The method of  claim 1  wherein said polyelectrolyte complex consists of said polyanion and said polycation. 
     
     
         3 . The method of  claim 1  wherein said providing step comprises mixing said polyanion, said polycation, and said gel breaking agent together in solution; and ceasing mixing to form said polyelectrolyte complex entrapping or encapsulating said gel breaking agent. 
     
     
         4 . The method of  claim 3  wherein said polycation and gel breaking agent are first mixed together separately prior to adding said polyanion. 
     
     
         5 . The method of  claim 3  wherein said polyanion and gel breaking agent are first mixed together separately prior to adding said polycation. 
     
     
         6 . The method of  claim 1  wherein said providing step comprises the steps of:
 mixing said polycation and said gel breaking agent together in a solution; 
 adding said polyanion to said solution and continuing mixing such that a polyelectrolyte complex forms and entraps or encapsulates said gel breaking agent. 
 
     
     
         7 . The method of  claim 6  wherein said gel breaking agent is an enzymatic gel breaking agent. 
     
     
         8 . The method of  claim 6  wherein said providing step further comprises dialyzing said polyelectrolyte complex solution to isolate a polyelectrolyte nanoparticle having said gel breaking agent entrapped or encapsulated therein. 
     
     
         9 . The method of  claim 1  wherein the polyelectrolyte complex has a polyanion/polycation shell and corona configuration. 
     
     
         10 . The method of  claim 1  wherein the gel breaking agent is an enzymatic gel breaking agent. 
     
     
         11 . The method of  claim 1  wherein the gel breaking agent is selected from the group consisting of one or more of amylase, amyloglucosidase, invertase, maltase, cellulase, pectinase, xanthanase, and hemicellulase. 
     
     
         12 . The method of  claim 1  wherein said gel breaking agent is an oxidizer. 
     
     
         13 . The method of  claim 12  wherein said oxidizer is selected from the group consisting of one or more of sodium persulfate, potassium persulfate, magnesium peroxide, and ammonium persulfate. 
     
     
         14 . The method of  claim 1  wherein said polycation is selected from the group consisting of chitosan, polyethyleneimine, and poly-L-lysine. 
     
     
         15 . The method of  claim 1  wherein said polyanion comprises dextran sulfate. 
     
     
         16 . The method of  claim 1  wherein said polyelectrolyte complex further includes a monovalent or bivalent cation selected from the group consisting of sodium ion and calcium ion or an anion selected from the group consisting of triphosphate ion, chloride ion, and sulfate ion. 
     
     
         17 . A fracturing fluid for an oil and gas well, wherein said fracturing fluid has a gel breaking agent therein, and wherein said gel breaking agent is entrapped or encapsulated within a polyelectrolyte complex consisting essentially of a polycation and a polyanion. 
     
     
         18 . The fracturing fluid of  claim 17  wherein said polyelectrolyte complex consists of said polyanion and said polycation. 
     
     
         19 . The fracturing fluid of  claim 17  wherein the gel breaking agent is an enzymatic gel breaking agent. 
     
     
         20 . The fracturing fluid of  claim 19  wherein the enzymatic breaker is selected from the group consisting of one or more of amylase, amyloglucosidase, invertase, maltase, cellulase, pectinase, xanthanase, and hemicellulase. 
     
     
         21 . The fracturing fluid of  claim 17  wherein said gel breaking agent is an oxidizer. 
     
     
         22 . The fracturing fluid of  claim 21  wherein said oxidizer is selected from the group consisting of one or more of sodium persulfate, potassium persulfate, magnesium peroxide, and ammonium persulfate. 
     
     
         23 . The fracturing fluid of  claim 17  wherein the polyelectrolyte complex has a polyanion/polycation shell and corona configuration. 
     
     
         24 . The fracturing fluid of  claim 17  wherein said polycation is selected from the group consisting of chitosan, polyethyleneimine, and poly-L-lysine. 
     
     
         25 . The fracturing fluid of  claim 17  wherein said polyanion comprises dextran sulfate. 
     
     
         26 . The fracturing fluid of  claim 17  wherein said polyelectrolyte complex further includes a monovalent or bivalent cation selected from the group consisting of sodium ion and calcium ion or an anion selected from the group consisting of triphosphate ion, chloride ion, and sulfate ion.