适用于万米深井的大温差水泥浆.

In cementing operation in ultradeep wells with long cementing sections, there is a large difference between the temperature at the top of the cement slurry and that at the bottom of the cement slurry. The low temperature at the top of the cement slurry retards the development of the strength of the set cement. To solve this problem, an early strength additive named EDTA-LDH (EDTA intercalated hydrotalcite) was developed through water solution polymerization. A cement slurry for working at big temperature difference conditions was formulated with EDTA-LDH. Laboratory experimental results show that this early strength additive has retarding effect to some extent; at a concentration of 2.0% EDTA-LDH and 4.0% retarder, a cement slurry has thickening time of 509 min at 240 ℃. After aging at 60 ℃ for 1 d or at 30 ℃ for 6 d, the cement slurry has compressive strengths of both greater than 7 MPa, and experiences maximum temperature difference of 210 ℃. The use of EDTA-LDH is beneficial to the development of the strength of the cement slurry column in low temperature without affecting the adjustability of the thickening time of the cement slurry. This early strength additive can work normally at temperatures above 300 ℃, and is suitable for cementing wells with large temperature differences. [ABSTRACT FROM AUTHOR]