Method of cementing
AssigneeThe Dow Chemical Company
InventorRobert C. Martin
Life of this patent
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Abstract
A cement composition is provided containing portland cement; calcium sulfate hemihydrate; an alkali metal nitrate; one or more retarders selected from the group consisting of a low molecular weight hydroxypolycarboxylic acid and sodium, potassium, and lithium salts thereof, and an alkaline hexametaphosphate; and as optional ingredients, calcium chloride and/or a condensation product of mononaphthalene sulfonic acid and formaldehyde; said ingredients being present in amounts effective to provide a cement which will set within a desired period of time at temperatures below about 80.degree. F down to below freezing, e.g. 32.degree. F, to provide a monolithic mass having adequate strength.
Claims14
A method of cementing the low temperature zone of an environment having a low temperature zone below about 80.degree. F, which comprises providing a cement slurry, transporting said slurry to said low temperature zone, and permitting the slurry to set up in said low temperature zone, wherein the slurry comprises portland cement and the calcium sulfate hemihydrate form of gypsum in a weight ratio of from 3:1 to 1:3 and, based on the total weight of said portland cement and gypsum:
- a. from about 5 to about 25 percent alkali metal nitrate;
- b. from about 0.1 to about 2 percent of at least one retarder selected from the group consisting of
- 1. a low molecular weight polycarboxylic acid,
- 2. a sodium, potassium, or lithium salt of a low molecular weight polycarboxylic acid, and
- 3. an alkaline hexametaphosphate;
- and
- c. from about 25 to about 50 percent water.
Dependencies are inferred from the claim text.