Apparatus and process for fracture conductivity tuning

Patent metadata

Field	Value
Publication number	US-12168922-B2
Application number	US-202318363003-A
Country	US
Kind code	B2
Filing date	Aug 1, 2023
Priority date	Sep 16, 2022
Publication date	Dec 17, 2024
Grant date	Dec 17, 2024

Abstract

Tuning fracture hydraulic conductivity can be provided so that high hydraulic conductivity in high temperature zones and low hydraulic conductivity in low temperature zones can be defined in enhanced geothermal systems (EGS). Uniform thermal gradient along flow paths can be provided or defined to help provide such conductivity zones. Experimentation performed to evaluate embodiments showed that embodiments could prevent appearance of dominant flow paths between the wells and maintain high heat extraction rates. Embodiments can greatly increase cumulative heat extraction. Embodiments can also be provided for application solely to the injection wells. Other embodiments can position tuning agents between the wells and still help provide control of the fluid flow in the reservoir and enhance heat extraction.

First claim

What is claimed is:

1. A method of fracture conductivity tuning comprising:
positioning elements in a geological system for adjustable hydraulic conductivity based on surrounding temperature of fractures within a subsurface of the geological system to provide a uniform or substantially uniform heat extraction via working fluid passing through the fractures;
wherein the elements comprise thermally sensitive proppants and/or adjustable clogging material (ACM), wherein the thermally sensitive proppants comprise calcium carbonate, one or more shape memory polymers, and/or at least one metal, and wherein the ACM comprises one or more inorganic salts, one or more polymers and/or one or more organic salts; and
wherein the elements are placed in the fractures and at least one injection well in fluid communication with the fractures.

2. The method of claim 1 , wherein the elements are thermally sensitive proppants and the positioning of the elements in the geological system comprises injecting the thermally sensitive proppants into the fractures, at least one injection well in fluid communication with the fractures, and/or at least one production well in fluid communication with the fractures.

3. The method of claim 2 , wherein the thermally sensitive proppants are configured so that the thermally sensitive proppants deform to expand when the surrounding temperature is below a first pre-selected maximum temperature for a first temperature zone and are configured to be smaller when at a second pre-selected temperature that is above a second pre-selected minimum temperature for a second temperature zone.

4. The method of claim 3 , wherein the first temperature zone is a lower temperature zone, the second temperature zone is a higher temperature zone and the thermally sensitive proppants comprise calcium carbonate.

5. The method of claim 4 , wherein the thermally sensitive proppants remain at a first size when the surrounding temperature is at the second pre-selected temperature and are enlarged to have a second size that has a greater volume than the first size when the surrounding temperature is below the first pre-selected maximum temperature for the first temperature zone.

6. The method of claim 4 , wherein deformation of the thermally sensitive proppants is configured to occlude the fractures and diminish or reduce hydraulic conductivity when the surrounding temperature is in the first temperature zone.

7. The method of claim 2 , wherein the thermally sensitive proppants are injected into the at least one injection well.

8. The method of claim 2 , wherein the thermally sensitive proppants are injected into the at least one production well.

9. The method of claim 2 , wherein the thermally sensitive proppants are injected into the fractures.

10. The method of claim 2 , wherein the thermally sensitive proppants are injected into the fractures and the at least one injection well.

11. The method of claim 2 , wherein the thermally sensitive proppants are injected into the fractures and the at least one production well.

12. The method of claim 2 , wherein the thermally sensitive proppants are thermally sensitive coated proppants.

13. The method of claim 2 , wherein the thermally sensitive proppants are thermally sensitive proppants that are injected and the method also comprises:
injecting additional proppants.

14. The method of claim 1 , wherein the geological system is an enhanced geothermal system (EGS) or a geothermal system.

15. The method of claim 1 , wherein the elements include the ACM, the ACM having a temperature sensitive solubility such that the ACM is in a solution state when at or above a first temperature and in a solid state at or below a second temperature; and
wherein the positioning of the elements in the geological system comprises injecting the ACM into the fractures, at least one injection well in fluid communication with the fractures, and/or at least one production well in fluid communication with the fractures.

16. The method of claim 15 , comprising:
the ACM forming at least one lining in the fractures when the surrounding temperature is at or below the first temperature; and
the at least one lining dissolving when the surrounding temperature is at or above the second temperature.

17. An apparatus for fracture conductivity tuning comprising:
at least one injection well;
fractures communicatively connected to the at least one injection well such that a working fluid injectable via the at least one injection well passes through the fractures to at least one production well; and
thermally expansive elements being positioned in the at least one injection well and the fractures to adjust fracture conductivity of heat to the working fluid, the thermally expansive elements configured to solidify to a solid or enlarge from a first size to a second size to have a greater volume when at a temperature that is below a first pre-selected temperature and the thermally expansive elements are configured to liquify or be at their first size when at a temperature that is above a second pre-selected temperature, the second pre-selected temperature being greater than the first pre-selected temperature;
wherein the thermally expansive elements comprise thermally sensitive proppants and/or adjustable clogging material (ACM), wherein the thermally sensitive proppants comprise calcium carbonate, one or more shape memory polymers, and/or at least one metal, and wherein the ACM comprises one or more inorganic salts, one or more polymers and/or one or more organic salts.

18. The apparatus of claim 17 , wherein the first pre-selected temperature is a defined maximum temperature for a first zone of conductivity and the second pre-selected temperature is a defined minimum temperature for a second zone of conductivity, conductivity of the second zone being greater than conductivity of the first zone.

19. The apparatus of claim 17 , wherein the thermally expansive elements include proppants comprised of calcium carbonate and/or are the ACM, the ACM having a temperature sensitive solubility.

20. The apparatus of claim 19 , wherein the thermally expansive elements include the ACM, the ACM having the temperature sensitive solubility such that the ACM forms at least one lining in the fractures when the surrounding temperature is at or below the first pre-selected temperature and the at least one lining dissolves when the surrounding temperature is above the second pre-selected temperature.

21. The apparatus of claim 17 , wherein the thermally expansive elements include the thermally sensitive proppants, each of the thermally sensitive proppants being comprised of a thermally sensitive coating that covers a body of the proppant.

22. The apparatus of claim 17 , wherein the thermally expansive elements include the thermally sensitive proppants.

Assignees

• Penn State Res Found

Inventors

• Dahi Taleghani Arash

Classifications

• Y02E10/10

  Geothermal energy · CPC title

• C09K8/80 Primary

  Compositions for reinforcing fractures, e.g. compositions of proppants used to keep the fractures open · CPC title

• E21B43/267 Primary

  reinforcing fractures by propping · CPC title

• C09K8/805

  Coated proppants · CPC title