Slow-release scale inhibiting compositions
A coated particulate composition includes a vitreous polyphosphate glass particulate and a coating on at least a portion of the surface of the particulate, the coating comprising a water-insoluble polymer or a water-insoluble particulate, wherein the coating weight is about 0.01 wt % to 90 wt % of the mass of the coated particulate. The particulates provide long-term scale inhibition downhole in subterranean reservoirs where temperatures exceed 70° C.
1. A composition comprising:
a vitreous polyphosphate glass particulate; and
a coating on at least a portion of the surface of the vitreous polyphosphate glass particulate, the coating comprising a water-insoluble polymer comprised of a vinylidene chloride-methyl acrylate copolymer,
wherein the coating weight is about 5 wt % to 25 wt % of the mass of the composition, and the vitreous polyphosphate particulate has a particle size of about 10 to 30 mesh.
2. The composition of claim 1 wherein the coating weight is about 10 wt % to 20 wt % of the mass of the composition.
3. The composition of claim 1 wherein the coating is about 10 wt % to 15 wt % of the mass of the composition.
4. The composition of claim 1 wherein the coating is about 5 wt % to 15 wt % of the mass of the composition.
5. The composition of claim 1 further comprising a layer of talc on the surface of the vitreous polyphosphate glass particulate.
6. The composition of claim 3 further comprising a layer of talc on the surface of the vitreous polyphosphate glass particulate, on the surface of the coating, or on the surface of both the vitreous polyphosphate glass particulate and the coating.
7. A method of making the composition of claim 1 , the method comprising
applying the vitreous polyphosphate glass particulate to a fluidized bed reactor;
applying the coating of the water-insoluble polymer on the surface of the vitreous polyphosphate glass particulate while the glass particulate is present in the fluidized bed to form a coated particulate;
optionally drying the coated particulate; and
collecting the coated particulate.
8. The method of claim 7 wherein the coating is applied as an emulsion, dispersion, or solution, followed by drying.
9. The method of claim 8 wherein the coating is applied as an aqueous emulsion.
10. The method of claim 7 wherein the coating is applied in the melt, followed by cooling.
11. The method of claim 7 wherein the method is a batchwise method, further wherein one or more portions of the coated particulate are collected while leaving one or more additional portions of the coated particulate in the fluidized bed for additional applying of water insoluble polymer.
12. The method of claim 7 wherein the vitreous polyphosphate glass particulate has a particle size of about 10 to 30 mesh.
13. An injectate composition comprising a water source and about 0.001 wt % to 10 wt % of the composition of claim 1 .
14. The injectate composition of claim 13 wherein the water source is produced water.
15. The injectate composition of claim 13 further comprising a proppant.
16. The injectate composition of claim 13 wherein the composition comprises a mixture of coated particulates having different coating weights.
17. A method of treating an oil or gas well, the method comprising:
introducing the composition of claim 1 to a well to reduce the formation of scale in a formation, in a production line downhole, or at the surface of the well.