Resin coated proppants with antimicrobial additives

Abstract

Proppants are used in oil and gas extraction, particularly in fracking operations. The invention relates to resin coated proppants. The coatings on proppants have antimicrobial materials incorporated within these coatings. The antimicrobially active agents are incorporated in a concentration less than 70% by weight of the coatings or the active agent from these coatings can be released from these coatings in the environment of the proppants.

1 . A method for producing particles having antimicrobial properties, wherein the surfaces of the particles are functionalized by a functionalization agent, and the functionalized particles are produced by grinding one or more metal compounds in a liquid medium wherein the functionalization agent is added to the said medium. 
     
     
         2 . The method of  claim 1 , wherein the liquid medium is aqueous. 
     
     
         3 . The method of  claim 2 , wherein the functionalization agent is present as a suspension or an emulsion or is soluble in the liquid medium. 
     
     
         4 . The method of  claim 1 , wherein the average size of the functionalized particles produced is less than 1,000 nm. 
     
     
         5 . The method of  claim 1 , wherein the weight ratio of the metal compound to the functionalization agent in the liquid medium is at least 1:1. 
     
     
         6 . The method of  claim 1 , wherein the metal compounds are one or more metals selected from the list of copper, silver and zinc. 
     
     
         7 . The method of  claim 6 , wherein the metal compounds are selected from cuprous halides, silver halides, minerals containing silver halides and copper halides; oxides of silver, copper and zinc; and CuSCN. 
     
     
         8 . The method of  claim 1 , where more than one functionalization agent is used and the more than one functionalization agent are added at the same time or at different times into the grinding process. 
     
     
         9 . The method of  claim 2 , where the said liquid medium further contains at least one salt with high water solubility. 
     
     
         10 . The method of  claim 9 , wherein the salt with high water solubility is selected from the salts of lithium, sodium, potassium, calcium, copper, silver, barium and zinc. 
     
     
         11 . The method of  claim 1 , wherein the functionalization agent has a molecular weight of at least 60. 
     
     
         12 . The method of  claim 11 , where in the functionalization agent is selected from polymers, monomers and surfactants. 
     
     
         13 . A method for producing particles having antimicrobial properties, wherein the surfaces of the particles are functionalized by a functionalization agent, and the functionalized particles are produced by grinding one or more copper halides or silver halides in a liquid medium and wherein the functionalization agent is added to the liquid medium. 
     
     
         14 . The method of  claim 13 , wherein the cuprous halide is CuI. 
     
     
         15 . The method of  claim 13 , wherein the functionalization agent is selected from a polymer or a copolymer of vinyl pyrrolidone. 
     
     
         16 . The method of  claim 13 , wherein the medium further comprises a salt with high water solubility selected from an iodide salt of lithium, sodium and potassium. 
     
     
         17 . The method of  claim 14 , wherein the aqueous medium additionally comprises acetonitrile. 
     
     
         18 . A method for producing particles having antimicrobial properties, wherein the surfaces of the said particles are functionalized by a functionalizing agent, and functionalized particles are produced by grinding cuprous iodide in an aqueous medium to which the functionalization agent is added and the said functionalizing agent is selected from a polymers, monomers and surfactants. 
     
     
         19 . The method in  claim 18 , wherein the functionalization agent comprises at least one polymer or a copolymer of vinyl pyrrolidone.