THERMALLY CONDUCTIVE CEMENTS AND METHODS FOR USE THEREOF

Abstract

Cementing compositions contain water, a cement and an additive for adjusting thermal conductivity. The additive for adjusting thermal conductivity may be graphite, graphene, aluminum oxide, hematite, copper metal, copper oxide, aluminum, amorphous carbon, gallium metal, iron metal, magnesium oxide, nickel metal, nickel oxide, tin metal, tin oxide, zinc metal or zinc oxide, or combinations thereof. Such compositions may have thermal conductivities exceeding 2 W/mK. Such compositions may be useful in closed loop geothermal completions or for encasing electrical cables.

Claims

1. A composition, comprising: water; a cement; and an additive for adjusting thermal conductivity.

2. The composition of claim 1, wherein the additive for adjusting thermal conductivity comprises graphite, graphene, silicon carbide, aluminum oxide, hematite, copper metal, copper oxide, aluminum, amorphous carbon, gallium metal, iron metal, magnesium oxide, nickel metal, nickel oxide, tin metal, tin oxide, zinc metal or zinc oxide, or combinations thereof.

3. The composition of claim 1, wherein the additive for adjusting thermal conductivity is present in the composition at a concentration between 0.1% and 75% by weight of cement; wherein the thermal conductivity of the composition is between 3 W/mK and 100 W/mK.

4. (canceled)

5. The composition of claim 1, wherein the composition further comprises silica at a concentration between 0.1 wt % and 100 wt % by weight of the hydraulic cement; wherein the composition has a density between 10 and 20 lbm/gal.

6. (canceled)

7. The composition of claim 1, wherein the composition has a multimodal particle size distribution comprising two or more sets of particles with different sizes.

8. The composition of claim 1, wherein the additive for adjusting thermal conductivity comprises particles, ribbons, fibers or flakes, or combinations thereof; wherein the composition has a solid volume fraction between 30% and 50%.

9. (canceled)

10. The composition of claim 1, wherein the cement comprises portland cement, high alumina cement, lime/silica blends, fly ashes, bioashes, metakaolin, kaolin, blast furnace slags, cement kiln dust, cement bypass dust or geopolymers, or combinations thereof.

11. A method for cementing a subterranean well, comprising: preparing a pumpable composition comprising water, a cement and an additive for adjusting thermal conductivity; placing the pumpable composition in the subterranean well; and causing the pumpable composition to set and develop strength.

12. The method of claim 11, wherein the additive for adjusting thermal conductivity comprises graphite, graphene, silicon carbide, aluminum oxide, hematite, copper metal, copper oxide, aluminum, amorphous carbon, gallium metal, iron metal, magnesium oxide, nickel metal, nickel oxide, tin metal, tin oxide, zinc metal or zinc oxide, or combinations thereof.

13. The method of claim 11, wherein the additive for adjusting thermal conductivity is present in the composition at a concentration between 0.1% and 75% by weight of cement; wherein the thermal conductivity of the composition is between 3 W/mK and 100 W/mK.

14. (canceled)

15. The method of claim 11, wherein the composition further comprises silica at a concentration between 0.1 wt % and 100 wt % by weight of the hydraulic cement; wherein the composition has a density between 10 and 20 lbm/gal.

16. (canceled)

17. The method of claim 11, wherein the composition has a multimodal particle size distribution comprising two or more sets of particles with different sizes.

18. The method of claim 11, wherein the additive for adjusting thermal conductivity comprises particles, ribbons, fibers or flakes, or combinations thereof; wherein the composition has a solid volume fraction between 30% and 50%.

19. (canceled)

20. The method of claim 11, wherein the cement comprises portland cement, high alumina cement, lime/silica blends, fly ashes, bioashes, metakaolin, kaolin, blast furnace slags, cement kiln dust, cement bypass dust or geopolymers, or combinations thereof

21. A method for installing electrical cables, comprising: preparing a pumpable composition comprising water, a cement and an additive for adjusting thermal conductivity; encasing the electrical cables with the pumpable composition; and causing the pumpable composition to set and develop strength.

22. The method of claim 21, wherein the additive for adjusting thermal conductivity comprises graphite, graphene, silicon carbide, aluminum oxide, hematite, copper metal, copper oxide, aluminum, amorphous carbon, gallium metal, iron metal, magnesium oxide, nickel metal, nickel oxide, tin metal, tin oxide, zinc metal or zinc oxide, or combinations thereof.

23. The method of claim 21, wherein the additive for adjusting thermal conductivity is present in the composition at a concentration between 0.1% and 75% by weight of cement; wherein the thermal conductivity of the composition is between 3 W/mK and 100 W/mK.

24. (canceled)

25. The method of claim 21, wherein the composition further comprises silica at a concentration between 0.1 wt % and 100 wt % by weight of the hydraulic cement; wherein the composition has a density between 10 and 20 lbm/gal.

26. (canceled)

27. The method of claim 21, wherein the composition has a multimodal particle size distribution comprising two or more sets of particles with different sizes.

28. The method of claim 21, wherein the additive for adjusting thermal conductivity comprises particles, ribbons, fibers or flakes, or combinations thereof; wherein the composition has a solid volume fraction between 30% and 50%.

29. (canceled)

30. The method of claim 21, wherein the cement comprises portland cement, high alumina cement, lime/silica blends, fly ashes, bioashes, metakaolin, kaolin, blast furnace slags, cement kiln dust, cement bypass dust or geopolymers, or combinations thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 shows a schematic of a system that can deliver a grout to a downhole location for grouting the annulus between a heat transfer loop and a subterranean formation.

[0021] FIG. 2 is an illustration of a conventional geothermal power generation system.

[0022] FIG. 3 is an illustration of an offshore windmill installation wherein the generated power is transmitted to an onshore power station.

DETAILED DESCRIPTION

[0023] In the following description, numerous details are set forth to provide an understanding of the present disclosure. However, it may be understood by those skilled in the art that the methods of the present disclosure may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.

[0024] At the outset, it should be noted that in the development of any such actual embodiment, numerous implementation-specific decisions are made to achieve the developer's specific goals, such as compliance with system related and business related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. In addition, the composition used/disclosed herein can also comprise some components other than those cited. In the summary of the disclosure and this detailed description, each numerical value should be read once as modified by the term about (unless already expressly so modified), and then read again as not so modified unless otherwise indicated in context. The term about should be understood as any amount or range within 10% of the recited amount or range (for example, a range from about 1 to about 10 encompasses a range from 0.9 to 11). Also, in the summary and this detailed description, it should be understood that a concentration range listed or described as being useful, suitable, or the like, is intended that any concentration within the range, including the end points, is to be considered as having been stated. For example, a range of from 1 to 10 is to be read as indicating each possible number along the continuum between about 1 and about 10. Furthermore, one or more of the data points in the present examples may be combined together, or may be combined with one of the data points in the specification to create a range, and thus include each possible value or number within this range. Thus, even if specific data points within the range, or even no data points within the range, are explicitly identified or refer to a few specific, it is to be understood that inventors appreciate and understand that any data points within the range are to be considered to have been specified, and that inventors possessed knowledge of the entire range and the points within the range.

[0025] As used herein, embodiments refers to non-limiting examples disclosed herein, whether claimed or not, which may be employed or present alone or in any combination or permutation with one or more other embodiments. Each embodiment disclosed herein should be regarded both as an added feature to be used with one or more other embodiments, as well as an alternative to be used separately or in lieu of one or more other embodiments. It should be understood that no limitation of the scope of the claimed subject matter is thereby intended, any alterations and further modifications in the illustrated embodiments, and any further applications of the principles of the application as illustrated therein as would normally occur to one skilled in the art to which the disclosure relates are contemplated herein.

[0026] Moreover, the schematic illustrations and descriptions provided herein are understood to be examples only, and components and operations may be combined or divided, and added or removed, as well as re-ordered in whole or part, unless stated explicitly to the contrary herein.

[0027] In an aspect, embodiments relate to compositions. The compositions comprise water, a cement and an additive for adjusting thermal conductivity.

[0028] In a further aspect, embodiments relate to methods for cementing a subterranean well. A pumpable composition is prepared that comprises water, a cement and an additive for adjusting thermal conductivity. The pumpable composition is placed in the subterranean well, after which the composition sets and develops strength.

[0029] In a further aspect, embodiments relate to methods for installing electrical cables. A pumpable composition is prepared that comprises water, a cement and an additive for adjusting thermal conductivity. The electrical cables are encased by the pumpable composition, after which the composition sets and develops strength. The present disclosure is not limited to cables that may be installed underground. Scenarios where cables are lying on an ocean floor or floating in water are also envisioned.

[0030] For all aspects, the additive for adjusting thermal conductivity may comprise graphite, graphene, silicon carbide, aluminum oxide, hematite, copper metal, copper oxide, aluminum, amorphous carbon, gallium metal, iron metal, magnesium oxide, nickel metal, nickel oxide, tin metal, tin oxide, zinc metal or zinc oxide, or combinations thereof.

[0031] The additive for adjusting thermal conductivity may be present in the composition at a concentration between 0.1% and 75% by weight of cement (BWOC), or between 25% and 45% BWOC, or between 5% and 30% BWOC. For graphite, the concentration may be between 5% and 30% BWOC. For silicon carbide, the concentration may be as high as 75% BWOC.

[0032] The composition, once cured and hardened, may have a thermal conductivity greater than 2 W/mK, between 3 W/mK and 100 W/mK, or between 5 W/mK and 8 w/mK.

[0033] The composition may have a density between 10 lbm/gal and 20 lbm/gal (1200 and 2400 kg/m.sup.3), or between 10 lbm/gal and 17 lbm/gal (1200 and 2040 kg/m.sup.3).

[0034] The composition may further comprise silica. The silica may be present at a concentration between 0.1% and 100% BWOC, or between 35% and 60% BWOC, or between 40% and 60% BWOC. Silica may be present in the composition to prevent strength retrogression when the composition is cured at temperatures exceeding 110 C. (230 F.).

[0035] The additive for adjusting thermal conductivity may have a particle size between about 50 m and 470 m, or between 170 m and 470 m.

[0036] In some embodiments, the composition may have a multimodal particle size distribution comprising at least two sets of particles with different sizes. For example, the composition may be trimodal, comprising fine, medium and coarse particles. Such compositions are available from Schlumberger under the general name CemCRETE. In such compositions, the additive for adjusting thermal conductivity may be present in any of the three particle-size categories.

[0037] The additive for adjusting thermal conductivity may be in the form of particles, ribbons, fibers or flakes, or combinations thereof.

[0038] The composition may have a solid volume fraction (SVF) between about 30% and 50%, or between about 30% to 45%.

[0039] For all aspects, the cement may comprise portland cement, high alumina cement, lime/silica blends, fly ashes, blast furnace slags, bioash, metakaolin, kaolin, cement kiln dust, cement bypass dust or geopolymers, or combinations thereof.

[0040] For all aspects, the composition may be pumpable during the placement period. For example, the consistency of the composition may be lower than 70 Bearden units (Bc) throughout the placement period. The yield value (Ty) may be between 7 and 75 lbf/100 ft.sup.2 during the placement period. The viscosity of the composition may be lower than about 1000 cP at a shear rate of 100 sec.sup.1 during the placement period. After placement, the composition may set and develop strength.

[0041] For all aspects, the composition may further comprise additives including accelerators, retarders, extenders, weighting agents, dispersants, fluid-loss additives, antifoam agents, defoamers, antisettling additives, or gases (e.g., air and nitrogen) or combinations thereof.

EXAMPLES

[0042] In the following examples, cement systems of varying thermal conductivity were prepared and tested. Thermal conductivity was determined by a method described by ASTM D5334-44: Standard Test Method For Determination of Thermal Conductivity of Soil and Soft rock By Thermal Needle Probe Procedure. A thermal conductivity meter from Thermtest Instruments was employed (TLS-100), and the 50-mm probe was used for all testing.

Example 1

[0043] As a comparative example, a cement slurry with the following composition was prepared: Class G cement+5% graphite by weight of cement (BWOC)+0.1% diutan gum (BWOC)+0.02 gal/sk sodium lignosulfonate retarder. The abbreviation sk refers to a 94-lb sack of portland cement. Sufficient water was added to achieve a solids volume fraction (SVF) of 41.5%. The slurry density was 15.8 lbm/gal (1900 kg/m.sup.3).

[0044] The slurry was cured at a temperature of 60 C. (140 F.) for 72 hr. After hardening the thermal conductivity was measured to be 1.45 W/mK.

Example 2

[0045] A cement slurry with the following composition was prepared. Class G cement+20% graphite (BWOC)+0.1% diutan gum (BWOC)+0.02 gal/sk sodium lignosulfonate retarder. Sufficient water was added to achieve an SVF of 44.2%. The slurry density was 15.8 lbm/gal (1900 kg/m.sup.3).

[0046] The slurry was cured at a temperature of 60 C. (140 F.) for 72 hr. After hardening the thermal conductivity was measured to be 2.81 W/mK.

Example 3

[0047] A cement slurry with the following composition was prepared. Class G cement+30% graphite (BWOC)+0.1% diutan gum (BWOC)+0.02 gal/sk sodium lignosulfonate retarder. Sufficient water was added to achieve an SVF of 46.3%. The slurry density was 15.8 lbm/gal (1900 kg/m.sup.3).

[0048] The slurry was cured at a temperature of 60 C. (140 F.) for 72 hr. After hardening the thermal conductivity was measured to be 7.03 W/mK.

[0049] The preceding description has been presented with reference to present embodiments. Persons skilled in the art and technology to which this disclosure pertains will appreciate that alterations and changes in the described structures and methods of operation can be practiced without meaningfully departing from the principle, and scope of this present disclosure. Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.