| 摘要 |
A cementing composition useful in cementing oil, gas and water wells, comprising water, hydraulic cement and an effective amount of water soluble fluid loss additive comprised of a blend of a copolymer (i) of acrylamide/vinyl imidazole in a weight percent ratio of from about 95:5 to 5:95, said copolymer (i) having a molecular weight range of from about 100,000 to 3,000,000, and a copolymer (ii) of vinyl pyrrolidone and the sodium salt of vinyl sulfonate in a weight percent ratio of 80:20 to 20:80, said copolymer (ii) having a molecular weight range of from about 100,000 to 3,000,000. The blend is comprised of a weight percent ratio of copolymer (i) to copolymer (ii) in the range of 20:80 to 80:20. The composition can also optionally include a dispersant such as sodium or potassium salts or a sulfonated naphthalene formaldehyde condensate.
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