Expanding additive for cement composition
AssigneeNalco/Exxon Energy Chemicals, L.P.
InventorPing-Sun Cheung
Life of this patent
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Abstract
Deadburned magnesium oxides (calcined at a temperature of above about 4000.degree. F.) can be advantageously utilized as an expanding additive in cements utilized to seal a metallic casing into the bore hole of a well. The deadburned magnesium oxide additives are particularly effective when used in cements having a curing temperature of about 120-200.degree. C. and particularly at temperatures greater than about 150.degree. C.
Claims8
A method for preventing the shrinkage of cement utilized to fill the area between a bore hole of a well and a metallic well casing which comprises adding to the cement, prior to placing between the bore hole and the well casing from 0.1-20 weight percent of a deadburned magnesium oxide, said deadburned magnesium oxide having been calcined at a temperature of greater than about 4000.degree. F.
A cement useful for cementing the area between a bore hole of a well and a metallic well casing which comprises:
- a. cement;
- and,
- b. from 0.1-20 weight percent based on the total weight of the cement composition of a finely divided deadburned magnesium oxide, said magnesium oxide having been calcined at a temperature greater than about 4000.degree. F., and wherein said cement containing said magnesium oxide expands at a linear rate over the temperature range of 120-200.degree. C.
Dependencies are inferred from the claim text.