Super-hydrophobic, thermally insulating, thermal-shocks resistant well cement composites for completion of geothermal wells at hydrothermal temperatures of up to 300° C

Patent metadata

Field	Value
Publication number	US-11912927-B2
Application number	US-202117494477-A
Country	US
Kind code	B2
Filing date	Oct 5, 2021
Priority date	Oct 5, 2020
Publication date	Feb 27, 2024
Grant date	Feb 27, 2024

Abstract

A well cement composite and a method for making a well cement composite includes a mixture of calcium aluminate cement (CAC) and fly ash cenospheres (CS) in a weight ratio of from 30:70 to 80:20 CAC to CS; sodium metasilicate (SMS) in an amount of from 1 to 10% of the total weight of the mixture of CAC and CS; polymethylhydrosiloxane (PMHS) in an amount of from 0.5 to 6.0% of the total weight of the mixture of CAC and CS; and water in a weight ratio of from 0.5:1.0 to 1.2:1.0 of water to CAC and CS.

First claim

We claim:

1. A well cement composite comprising:
a mixture of calcium aluminate cement (CAC) and fly ash cenospheres (CS) in a weight ratio of from 30:70 to 80:20 CAC to CS;
sodium metasilicate (SMS) in an amount of from 1 to 10% of the total weight of the mixture of CAC and CS;
polymethylhydrosiloxane (PMHS) in an amount of from 0.5 to 6.0% of the total weight of the mixture of CAC and CS; and
water in a weight ratio of from 0.5:1.0 to 1.2:1.0 of water to CAC and CS.

2. The well cement composite according to claim 1 , wherein the CAC to CS weight ratio is about 60:40.

3. The well cement composite according to claim 1 , wherein the amount of SMS is about 6% by total weight of the CAC and CS mixture.

4. The well cement composite according to claim 1 , wherein the amount of PMHS is about 3% by total weight of the CAC and CS mixture.

5. The well cement composite according to claim 1 , wherein the ratio of water to CAC and CS is about 0.8:1.0.

6. The well cement composite according to claim 1 , wherein the CAC and the CS is mixed in an alkaline environment having a pH greater than 9.

7. The well cement composite according to claim 1 , wherein the CAC and the CS is mixed in an alkaline environment having a pH range between 8 and 12.5.

8. The well cement composite according to claim 1 , wherein the thermal conductivity of the well cement composite under water saturated conditions is less than 0.7 Watt per meter by Kelvin (W/mK).

9. The well cement composite according to claim 1 , wherein the well cement composite has a density of about 1.28 g/cm 3 .

10. A well cement composite comprising:
a mixture of calcium aluminate cement (CAC) and fly ash cenospheres (CS) in a weight ratio of from 30:70 to 80:20 CAC to CS;
sodium metasilicate (SMS) in an amount of from 1 to 10% of the total weight of the mixture of CAC and CS;
a siloxane with at least one hydrophobic functional group in an amount of from 0.5 to 6.0% of the total weight of the mixture of CAC and CS; and
water in a weight ratio of from 0.5:1.0 to 1.2:1.0 of water to CAC and CS.

11. A method of making a well cement composite comprising:
mixing polymethylhydrosiloxane (PMHS) with an aqueous solution of sodium metasilicate (SMS) to form an emulsion;
mixing fly ash cenospheres (CS) into the emulsion to release hydrogen gas and form a paste;
adding calcium aluminate cement (CAC) and water to the paste and mixing to form the well cement composite,
wherein the well cement composite comprises calcium aluminate cement (CAC) and fly ash cenospheres (CS) in a weight ratio of from 30:70 to 80:20 CAC to CS, sodium metasilicate (SMS) in an amount of from 1 to 10% of the total weight of CAC and CS, polymethylhydrosiloxane (PMHS) in an amount of from 0.5 to 6.0% of the total weight of CAC and CS, and water in a weight ratio of from 0.5:1.0 to 1.2:1.0 of water to CAC and CS.

12. The method of making a well cement composite according to claim 11 , wherein the CAC to CS weight ratio is about 60:40.

13. The method of making a well cement composite according to claim 11 , wherein the amount of SMS is about 6% by total weight of the CAC and CS.

14. The method of making a well cement composite according to claim 11 , wherein the amount of PMHS is about 3% by total weight of the CAC and CS.

15. The method of making a well cement composite according to claim 11 , wherein the weight ratio of water to CAC and CS is about 0.8:1.0.

16. The method of making a well cement composite according to claim 11 , wherein the well cement composite has a pH greater than 9.

17. The method of making a well cement composite according to claim 11 , wherein the has a pH range between 8 and 12.5.

18. The method of making a well cement composite according to claim 11 , wherein the thermal conductivity of the well cement composite under water saturated conditions is less than 0.7 Watt per meter by Kelvin (W/mK).

19. The method of making a well cement composite according to claim 11 , wherein the well cement composite has a density of about 1.28.

20. The method of making a well cement composite according to claim 11 , wherein the paste formed by mixing the CS and the emulsion comprises CS coated with polymethyl siloxane.

Assignees

• Brookhaven Science Ass Llc

Inventors

• Pyatina Tatiana
• Sugama Toshifumi

Classifications

• C09K8/467 Primary

  containing additives for specific purposes · CPC title

• C04B18/082

  Cenospheres · CPC title

• C04B20/1037

  obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds · CPC title

• C04B20/1051

  Organo-metallic compounds; Organo-silicon compounds, e.g. bentone · CPC title

• C04B24/42

  Organo-silicon compounds · CPC title