| 摘要 |
Very low molecular weight carboxymethylhydroxyethylcellulose polymers are used as additives for salt water cement slurries to lower the water loss therefrom when in contact with water permeable earth formations. The additives may also include hydroxycarboxy acids. The cellulose derivative has a DS of 0.1-0.7 (carboxymethyl), a molar ratio of ethylene oxide to anhydroglucose units of 0.6-2.8 and a molecular weight such that a 1 % by wt. aqueous solution at 25-5 DEG C has a viscosity (FANN) of 10-225 cps at 300 rpm/no. 1 spring. Typical hydroxycarboxy acid additives include gluconic, tartaric, lactic, citric or malic acid. |
