Method of cementing within a gas or oil well
A cement mix for cementing the well casing within a wellbore which contains a synergistic blend of an alkali metasilicate and/or alkali silicate, aluminum silicate and either silica fume or micro silica quartz along with a Portland cement. The cement mix, when combined with mix water, may render a cementitious slurry having a density less than or equal to 11.5 pounds per gallon (ppg); the amount of mix water in the cementitious slurry being between from about 200 to about 560 percent by weight of cement (BWOC). The compressive strength of such cementitious slurries, when cured, is in excess of 100 psi, more typically in excess of 200 psi, after 72 hours at 130° F.
1. A method of cementing within a gas or oil well penetrating a subterranean formation, the method comprising the steps of:
pumping into the well a cementitious slurry comprising water and a cement mix, wherein the cement mix comprises:
(a) a hydraulically-active cementitious material;
(b) between from about 0.1 to about 8 weight percent, by weight of cementitious material (BWOC), of an alkali metasilicate and/or alkali silicate;
(c) between from about 2 to about 10 percent BWOC of calcined kaolin or metakaolin; and
(d) between from about 0.5 to about 55 percent BWOC of silica fume or micro silica quartz; and
allowing the cementitious slurry to set.
2. A method of cementing within a gas or oil well penetrating a subterranean formation, the method comprising the steps of:
pumping into the well a cementitious slurry comprising water and a cement mix, wherein the cement mix comprises:
(a) a Class H Portland cement;
(b) between from about 0.1 to about 8 weight percent, by weight of cementitious material (BWOC), of an alkali metasilicate and/or alkali silicate;
(c) between from about 2 to about 10 percent BWOC of calcined kaolin or metakaolin; and
(d) between from about 0.5 to about 55 percent BWOC of silica fume; and
allowing the cementitious slurry to set.
3. A method of cementing within a gas or oil well penetrating a subterranean formation, the method comprising the steps of:
pumping into the well a cementitious slurry comprising water and a cement mix, wherein the cement mix comprises:
(a) a Class C Portland cement;
(b) between from about 0.1 to about 8 weight percent, by weight of cementitious material (BWOC), of an alkali metasilicate and/or alkali silicate;
(c) between from about 2 to about 10 percent BWOC of calcined kaolin or metakaolin; and
(d) between from about 0.5 to about 55 percent BWOC of micro silica quartz; and
allowing the cementitious slurry to set.
4. The method of claim 2 , wherein the density of the cementitious slurry is between from about 9.5 to about 11.5 ppg.
5. The method of claim 2 , wherein the amount of mix water in the cementitious slurry is between from about 200 to about 560 percent BWOC.
6. The method of claim 3 , wherein the density of the cementitious slurry is between from about 9.5 to about 11.5 ppg.
7. The method of claim 1 , wherein the hydraulically-active cementitious material is Portland cement.
8. The method of claim 7 , wherein the Portland cement is selected from the group consisting of API Class C and H cements.
9. The method of claim 1 , wherein component (d) is silica fume.
10. The method of claim 1 , wherein the alkali metasilicate and/or alkali silicate is selected from the group consisting of sodium metasilicate and sodium silicate.
11. The method of claim 10 , wherein component (b) is sodium metasilicate.
12. The method of claim 11 , wherein component (d) is silica fume.
13. The method of claim 1 , wherein the cement mix further contains a set retarder.
14. The method of claim 1 , wherein the cement mix further contains fly ash or pozzolan cement.
15. The method of claim 13 , wherein the set retarder is sodium lignosulfonate.
16. The method of claim 1 , wherein component (d) is micro silica quartz.
17. The method of claim 11 , wherein component (d) is micro silica quartz.
18. The method of claim 16 , wherein the cement mix further contains at least one component selected from the group consisting of aluminum oxide, iron oxide, calcium oxide and calcium sulfate.
19. The method of claim 2 , wherein the cement mix further contains at least one component selected from the group consisting of a set retarder, crystalline silica, gypsum and a naturally occurring solid hydrocarbon.
20. The method of claim 19 , wherein the set retarder is sodium lignosulfonate.
21. The method of claim 1 , wherein the amount of silica fume or micro silica quartz in the cement mix is less than or equal to 55 percent BWOC.
22. The method of claim 1 , wherein the density of the cementitious slurry is less than or equal to 11.5 pounds per gallon (ppg).
23. The method of claim 22 , wherein the density of the cementitious slurry is between from about 9.5 to about 11.5 ppg.
24. The method of claim 1 , wherein the amount of mix water in the cementitious slurry is between from about 200 to about 560 percent BWOC.
25. The method of claim 1 , wherein the compressive strength of the cementitious slurry, when cured, is in excess of 100 psi after 24 hours at 130° F.
26. The method of claim 2 , wherein the amount of mix water in the cementitious slurry is between from about 200 to about 560 percent BWOC.
27. The method of claim 25 , wherein the compressive strength of the cementitious slurry, when cured, is in excess of 100 psi after 72 hours at 130° F.
28. The method of claim 1 , wherein the cement mix further contains a lost circulation additive.
29. The method of claim 3 , wherein the compressive strength of the cementitious slurry, when cured, is in excess of 100 psi after 24 hours at 130° F.
30. The method of claim 3 , wherein the amount of mix water in the cementitious slurry is between from about 200 to about 560 percent BWOC.
31. The method of claim 3 , wherein the cement mix further contains a set retarder.