Controlled release solid scale inhibitors
View Patent ↗Compositions and methods of preparation and use for controlled release solid scale inhibitors used in hydraulic fracturing operations in oil and gas wells. The controlled release scale inhibitors comprise amorphous glass which is a reaction product of a phosphorus-containing compound, a calcium-containing compound, a magnesium-containing compound and base. The composition has a predetermined dissolution rate for controlled release of scale inhibitors in induced hydraulic fractures in hydraulic fracturing treatment of oil or gas wells.
1. A method of inhibiting scale formation in a subterranean petroleum formation, the method comprising:
mixing a scale inhibitor composition with a proppant to form a mixture; and
injecting the mixture under pressure into hydraulically generated fractures of a wellbore, the scale inhibitor composition comprising a reaction product of a combination comprising from about 20 to about 55 wt. % of a phosphorus-containing compound, about 1 to about 20 wt. % of a calcium-containing compound, about 1 to about 15 wt. % of a magnesium-containing compound, water, and from 11 to about 25 wt. % of a sodium- or potassium-containing base, based on the weight of the combination, the reaction product being in the form of a substantially amorphous glass, and the combination being substantially free of liquid hydrocarbon, and wherein the sodium- or potassium-containing base comprises sodium hydroxide, potassium hydroxide, trisodium phosphate, sodium carbonate, potassium carbonate, potassium bicarbonate, sodium bicarbonate, potassium acetate, sodium acetate, sodium benzoate, or a combination thereof; the phosphorus-containing compound and the sodium- or potassium-containing base being in a weight ratio of from 5:1 to 2:1,
wherein the substantially amorphous glass is particulate and has a particle size of from about 10 to about 30 mesh and whereby scale formation in the subterranean petroleum formation is inhibited.
2. The method of claim 1 , wherein the weight ratio is from 5:1 to about 2.3:1.
3. The method of claim 1 , wherein the weight ratio is from about 4:1 to about 2.7:1.
4. The method of claim 1 , wherein the phosphorus-containing compound comprises phosphoric acid, polyphosphoric acid, a phosphate, a phosphate ester, a phosphonate, or a combination thereof.
5. The method of claim 1 , wherein the calcium-containing compound comprises calcium hydroxide, calcium oxide, calcium carbonate, or a combination thereof.
6. The method of claim 1 , wherein the magnesium-containing compound comprises magnesium hydroxide, magnesium oxide, magnesium carbonate, or a combination thereof.
7. The method of claim 1 , wherein the composition comprises from about 20 to about 55 wt. % of the phosphorus-containing compound, about 3 to about 15 wt. % of the calcium-containing compound, about 2 to about 10 wt. % of the magnesium-containing compound, and about 11 to 20 wt. % of the sodium- or potassium-containing base, based on the weight of the combination.
8. The method of claim 1 , wherein the composition comprises from about 12.5 to about 25 wt. % of the sodium- or potassium-containing base based on the weight of the combination.
9. The method of claim 8 , wherein the composition comprises from about 15 to about 25 wt. % of the sodium- or potassium-containing base based on the weight of the combination.
10. The method of claim 1 , wherein the combination further comprises from about 2 to about 10 wt. % of an aluminum-containing compound comprised of alumina, aluminum hydroxide, aluminum oxide hydroxide, a naturally occurring or synthetic alumina-containing mineral or a polymorph thereof, an aluminate salt or a polymorph thereof, an organic aluminum or a combination thereof.
11. The method of claim 1 , wherein the substantially amorphous glass dissolves at a rate of loss of less than 60% of the starting total mass over a 28 day period, when heated to 300° F. in deionized water at a concentration of 5 g slowed release polyphosphate glass per 300 mL deionized water.
12. The method of claim 1 , wherein the composition comprises the reaction product of the combination consisting essentially of the phosphorus-containing compound, the calcium-containing compound, the magnesium-containing compound, water, and the sodium- or potassium-containing base.
13. The method of claim 12 , wherein the substantially amorphous glass dissolves at a rate of loss of less than 60% of the starting total mass over a 28 day period, when heated to 300° F. in deionized water at a concentration of 5 g slowed release polyphosphate glass per 300 mL deionized water.
14. The method of claim 12 , wherein the composition comprises from about 20 to about 55 wt. % of the phosphorus-containing compound, about 3 to about 15 wt. % of the calcium-containing compound, about 2 to about 10 wt. % of the magnesium-containing compound, and about 11 to 20 wt. % of the sodium- or potassium-containing base, based on the weight of the combination.
15. The method of claim 12 , wherein the composition comprises from about 20 to about 55 wt. % of the phosphorus-containing compound, about 3 to about 12 wt. % of the calcium-containing compound, about 4 to about 9 wt. % of the magnesium-containing compound, and about 11 to 20 wt. % of the sodium- or potassium-containing base, based on the weight of the combination.
16. The method of claim 1 , wherein the substantially amorphous glass has a coating on at least a portion of a surface of the particulate, the coating comprising a water-insoluble polymer, a water-insoluble particulate, or a combination thereof, wherein the coating weight is about 0.01 wt. % to 90 wt. % of the mass of the coated particulate.
17. The method of claim 1 , wherein the composition comprises from about 20 to about 55 wt. % of the phosphorus-containing compound, about 3 to about 12 wt. % of the calcium-containing compound, about 4 to about 9 wt. % of the magnesium-containing compound, and about 11 to 20 wt. % of the sodium- or potassium-containing base, based on the weight of the combination.
18. The method of claim 1 , wherein the composition comprises from about 20 to about 45 wt. % of the phosphorus-containing compound, about 3 to about 12 wt. % of the calcium-containing compound, about 4 to about 9 wt. % of the magnesium-containing compound, and about 12.5 to 20 wt. % of the sodium- or potassium-containing base, based on the weight of the combination.