COATED PARTICLES AND METHODS OF MAKING AND USING THE SAME
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.