Coated And Cured Proppants
Solid proppants are coated with a coating that exhibits the handling characteristics of a precured coating while also exhibiting the ability to form particle-to-particle bonds at the elevated temperatures and pressures within a wellbore. The coating includes a substantially homogeneous mixture of (i) at least one isocyanate component having at least 2 isocyanate groups, and (ii) a curing agent. The coating process can be performed with short cycle times, e.g., less than about 4 minutes, and still produce a dry, free-flowing, coated proppant that exhibits low dust characteristics during pneumatic handling but also proppant consolidation downhole for reduced washout and good conductivity.
1 - 33 . (canceled)
34 . A coated core particle that is substantially covered with a substantially cured coating that comprises at least one isocyanate component, a hydroxy-functional polyether polyol, at least one tin complex catalyst, wherein said coating can form particle-to-particle bonds under downhole conditions.
35 . The coated core particle of claim 34 , wherein said coating can form particle-to-particle bonds that exhibit an unconfined compressive strength sufficient to generate proppant consolidation and provide flowback control.
36 . The coated core particle of claim 34 , wherein said coating can form particle-to-particle bonds under downhole conditions that exhibit an unconfined compressive strength of greater than 100 psi.
37 . The coated core particle of claim 34 , wherein the coated core particle resists proppant flowback at elevated temperature and pressure.
38 . The coated core particle of claim 34 , wherein the coated core particle exhibits a negative TMA slope within the range of about 125° C. and 175° C.
39 . The coated core particle of claim 34 , wherein said coated core particle exhibits a loss of coating of less than 15 wt % when tested according to ISO 13503-5:2006(E).
40 . The coated core particle of claim 34 , wherein the coating comprises one or more of decarboxylated cashew nut oil, castor oil, cardol and cardanol.
41 . The coated core particle of claim 34 , wherein the coating further comprises an adhesion agent.
42 . The coated core particle of claim 41 , wherein the adhesion agent is a silane.
43 . The coated core particle of claim 34 , wherein the core particle is a ceramic core particle.
44 . The coated core particle of claim 34 , wherein the core particle is a sand particle.
45 . The coated core particle of claim 34 , wherein the coating further comprises a pigment, dye, or tint.
46 . The coated core particle of claim 34 , wherein the coating further comprises mica.
47 . A process for making the coated core particle of claim 34 , the process comprising mixing a core particle with at least one isocyanate component, a hydroxy-functional polyether polyol, and at least one tin complex catalyst under conditions to coat the core particle with a substantially cured coating that comprises at least one isocyanate component, a hydroxy-functional polyether polyol and at least one tin complex catalyst.
48 . The process of claim 47 , further comprising mixing the core particle with an adhesion agent.
49 . The process of claim 48 , wherein the adhesion agent is a silane.
50 . The process of claim 47 , wherein the core particle is a sand particle or a ceramic particle.
51 . The process of claim 47 , further comprising mixing the core particle with a pigment, dye, or tint.
52 . The process of claim 47 , wherein the process comprises:
a) mixing the core particle with a silane;
b) mixing the product of step a) with the polyol and the tin catalyst;
c) mixing the product of step b) with the isocyanate.
53 . The process of claim 52 , further comprising mixing the product of step c) with a silane.