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US 4,797,159 AGranted
Expandable cement composition
AssigneeDowell Schlumberger Incorporated
InventorLloyd B. Spangle
Life of this patent
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AssigneeDowell Schlumberger Incorporated
InventorLloyd B. Spangle
Estimating the term…
Particulate magnesium oxide prepared by calcining magnesium oxide at between about 1100.degree. C. and about 1500.degree. C. At least about 80% of the magnesium oxide particles are between about 150 microns to about 400 microns in diameter. This magnesium oxide is capable of producing expansion in set cements when the temperature thereof is at least about 60.degree. C. Preferably the magnesium oxide has been calcined at between about 1100.degree. C. to about 1300.degree. C. for about 1 to about 3 hours, and at least about 80% of the particles are between about 200 microns to about 325 microns. Further, the BET surface area of the particles is preferably between about 0.8 to about 1.8 m.sup.2 /g, and the acid neutralization time (using the method described) is between about 15 to 20 minutes, and further preferably between about 17 to about 25 minutes. Expandable cement compositions using such magnesium oxide, and a method of using them in cementing of wells, are also disclosed.
An expandable cement composition useful for cementing a well casing within the bore of a well, and which sets in no less than about 12 hours, comprising:
An expandable cement composition useful for cementing a well casing within the bore of a well, comprising:
A method of cementing a casing in a bore of a well, comprising placing a cement slurry composition between the casing and the bore, which composition comprises a hydratable cement and 0.25 to 3.75 percent by weight of cement particulate magnesium oxide produced by calcining magnesium oxide at between about 1100.degree. C. and about 1500.degree. C., which has at least about 80% of the particles between about 150 microns to about 400 microns in diameter, so as to produce on expansion of at least about 0.4% in the set cement within about 30 days during a period in which the bottom hole static temperature of the well is between about 70.degree. C. and about 290.degree. C.
A method of cementing a casing in a bore of a well,comprising placing a cement slurry composition between the casing and the bore, which composition comprises a hydratable cement and 0.25 to 3.75 percent by weight of cement particulate magnesium oxide produced by calcining magnesium oxide at between about 1100.degree. C. and about 1500.degree. C., which has at least about 80% of the particles between about 150 mirons to about 400 microns in diameter, so as to produce an expansion of at least about 0.4% in the set cement within about 30 days during a period in which the bottom hole static temperature of the well is between about 70.degree. C. and about 180.degree. C.
Dependencies are inferred from the claim text.