Cement Slurries for Well Bores

• US 20190218445A1
• Filed: 01/17/2018
• Published: 07/18/2019
• Est. Priority Date: 01/17/2018
• Status: Active Grant

• Current Assignee: American Cementing, LLC
• Original Assignee: BJ Services Company LLC (Baker Hughes Company)
• Inventors: Pernites, Roderick B., Padilla Florencia, Felipe, Clark, Jordan Lee, Gonzalez, Angel
• Granted Patent: US 10,450,494 B2
• Time in Patent Office: Days
• CPC Class Codes: C04B 14/14 Minerals of vulcanic origin granite C04B14/048
• CPC Class Codes: C04B 18/08 Flue dust , i.e. fly ash
• CPC Class Codes: C04B 20/008 Micro- or nanosized fillers, e.g. micronised fillers with particle size smaller than that of the hydraulic binder colloidal silica C04B14/062 ; silica fume C04B18/146
• CPC Class Codes: C04B 2103/0031 Type C
• CPC Class Codes: C04B 2103/0036 Type H
• CPC Class Codes: C04B 2103/0082 Segregation-preventing agents; Sedimentation-preventing agents
• CPC Class Codes: C04B 2103/10 Accelerators; Activators
• CPC Class Codes: C04B 2103/20 Retarders
• CPC Class Codes: C04B 2103/46 Water-loss or fluid-loss reducers, hygroscopic or hydrophilic agents, water retention agents
• CPC Class Codes: C04B 2111/1031 Lime-free or very low lime-content materials
• CPC Class Codes: C04B 28/04 Portland cements
• CPC Class Codes: C09K 8/46 containing inorganic binders, e.g. Portland cement
• CPC Class Codes: C09K 8/473 Density reducing additives, e.g. for obtaining foamed cement compositions
• CPC Class Codes: C09K 8/487 Fluid loss control additives; Additives for reducing or preventing circulation loss

Abstract

Cement slurries are provided for use in cementing oil and gas wells. The cement slurry comprises API Class C or Class H Portland cement and a pozzolan selected from the group consisting of pumice and mixtures of pumice and fly ash. Pumice is present in the mixtures in amounts at least about 40 wt % of the pozzolan. The weight ratio of the pozzolan to the cement is from about 35:65 to about 70:30. The novel cement slurries preferably will not comprise any additional lime, including hydrated lime, or other activators.

Claims

1. A settable cementitious slurry for use in a subterranean well, said cement slurry comprising cementitious components, said cementitious components consisting essentially of:

(a) API Class C or Class H Portland cement; and

(b) a pozzolan selected from the group consisting of pumice and mixtures of pumice and fly ash, wherein pumice is at least about 40 wt % of said pozzolan;

(c) wherein the weight ratio of said pozzolan to said cement is from about 35;

65 to about 70;

30; and

(d) wherein said pozzolan has an average particle size less than about 20 μ

m.

3. The cement slurry of claim 1, wherein pumice is at least about 50 wt % of said pozzolan.

4. The cement slurry of claim 1, wherein pumice is at least about 60 wt % of said pozzolan.

5. The cement slurry of claim 1, wherein said pozzolan is pumice.

8. The cement slurry of claim 1, wherein said pozzolan has an average particle size from about 5 to about 20 μ

m.

9. The cement slurry of claim 1, wherein said pozzolan has an average particle size from about 5 to about 10 μ

m.

10. The cement slurry of claim 1, wherein said pozzolan to cement ratio is from about 40:

60 to about 60;

40.

11. The cement slurry of claim 1, wherein said pozzolan to cement ratio is from about 50:

50 to about 60;

40.

12. The cement slurry of claim 1, wherein said cement slurry is substantially free of added lime.

13. The cement slurry of claim 8, wherein said cement slurry is substantially free of added lime.

14. The cement slurry of claim 9, wherein said cement slurry is substantially free of added lime.

16. The cement slurry of claim 1, wherein said cement slurry has a density of from about 10 to about 16 ppg.

17. The cement slurry of claim 1, wherein said cement slurry has a density of from about 11.5 to about 14.5 ppg.

18. The cement slurry of claim 1, wherein said cement slurry further comprises an additive selected from the group consisting of suspension agents, accelerators, retarders, fluid loss additives, dispersants, and free fluid additives.

19. A method of cementing, said method comprising:

(a) injecting a cement slurry of claim 1 in a subterranean well; and

(b) allowing said cement slurry to set.

20. A subterranean well, said subterranean well comprising a set cement slurry of claim 1.

21. The cement slurry of claim 8, wherein said pozzolan to cement ratio is from about 50:

50 to about 60;

40.

22. The cement slurry of claim 9, wherein said pozzolan to cement ratio is from about 50:

50 to about 60;

40.

23. A method of cementing, said method comprising:

(a) injecting a cement slurry of claim 8 in a subterranean well; and

(b) allowing said cement slurry to set.

24. A method of cementing, said method comprising:

(a) injecting a cement slurry of claim 9 in a subterranean well; and

(b) allowing said cement slurry to set.

25. A subterranean well, said subterranean well comprising a set cement slurry of claim 8.

26. A subterranean well, said subterranean well comprising a set cement slurry of claim 9.

2. (canceled)

6. (canceled)

7. (canceled)

15. (canceled)