Coated particles and methods of making and using the same

Abstract

Provided herein are coated particles, such as, for example, proppants comprising a coating. A coated particle of the present invention may swell upon contact with a solution having a salinity in a range of about 50 ppm to about 100,000 ppm and/or having a hardness in a range of about 1 ppm to about 150,000 ppm. The amount of swelling may vary by less than 50% over a salinity concentration in a range of about 50 ppm to about 100,000 ppm and/or a hardness concentration in a range of about 1 ppm to about 150,000 ppm. Also provided herein are methods of making coated particles and methods of using the same.

1 . A particle comprising a core and a coating on at least a portion of a surface of the core, the coating comprising a cross-linked, charge-modified biopolymer. 
     
     
         2 .- 20 . (canceled) 
     
     
         21 . The particle of  claim 1 , wherein the coating and/or particle further comprises a linker molecule, a binding agent, a surfactant, a viscosifying agent, a charged entity, an anti-clumping agent, a leavening agent, and/or an anti-caking agent. 
     
     
         22 .- 26 . (canceled) 
     
     
         27 . A method of preparing a coated particle, the method comprising:
 combining a biopolymer, a catalyst, a charge modifying agent, and a plasticizer to form a mixture;   reacting the biopolymer and the charge modifying agent to form a charge-modified biopolymer in the mixture; and   contacting the mixture comprising the charge-modified biopolymer with a core to form a coating comprising the charge-modified biopolymer on the core, thereby preparing the coated particle.   
     
     
         28 . The method of  claim 27 , further comprising adding a cross-linking agent to the mixture comprising the charge-modified biopolymer to form a cross-linked, charged-modified biopolymer. 
     
     
         29 . The method of  claim 27 , wherein the mixture comprising the charge-modified biopolymer is a melt extrudate. 
     
     
         30 . The method of  claim 27 , wherein contacting the mixture comprising the charge-modified biopolymer with the core comprises extruding the melt extrudate into and/or onto a mixture comprising a plurality of cores. 
     
     
         31 . The method of  claim 27 , wherein the mixture comprises the catalyst in an amount of about 0.5% to about 50% by weight of the biopolymer, the plasticizer in an amount of about 75% to about 500% by weight of the biopolymer, and the charge modifying agent in an amount of about 1% to about 75% by weight of the biopolymer. 
     
     
         32 . The method of  claim 27 , wherein the coated particle comprises a superabsorbent polymer. 
     
     
         33 . The method of  claim 27 , wherein the coated particle comprises a cationic biopolymer that is cross-linked. 
     
     
         34 . The method of  claim 27 , wherein the coated particle is prepared in-line with an extrusion process. 
     
     
         35 . The method of  claim 27 , wherein the step of reacting the biopolymer and the charge modifying agent is carried out using an extrusion process. 
     
     
         36 . The method of  claim 27 , further comprising contacting the coated particle with a cross-linking agent, optionally wherein the coating on the coated particle is cured. 
     
     
         37 . The method of  claim 27 , further comprising contacting the coated particle with a leavening agent. 
     
     
         38 . The method of  claim 37 , wherein the leavening agent comprises sodium bicarbonate and monocalcium phosphate. 
     
     
         39 . A particle prepared according to the method of  claim 27 . 
     
     
         40 . A method of using the particle prepared according to  claim 27 , the method comprising contacting a fluid and the particle. 
     
     
         41 . The method of  claim 40 , wherein the method is a method of fracturing a well and/or a geological formation. 
     
     
         42 . (canceled) 
     
     
         43 . The method of  claim 27 , wherein the mixture further comprises a binding agent. 
     
     
         44 . The method of  claim 43 , wherein the binding agent is an organosilane. 
     
     
         45 . The method of  claim 27 , further comprising, prior to contacting the mixture comprising the charge-modified biopolymer with the core, contacting a binding agent to the core.