Preparation and mechanism of tartaric acid-intercalated hydrotalcite retarder for oil-well cement

Abstract

In view of the existing problems of retarding agents, such as abnormal cementing of cement slurry, slow development of cement strength, low strength, poor thermal stability and excessive retarding, etc. In this study, tartaric acid-intercalated hydrotalcite (Mg/Al-TA-LDH) was prepared by ion exchange between tartaric acid and magnesium–aluminium hydrotalcite (Mg/Al-CO3-LDH). The results show that Mg/Al-CO3-LDH and Mg/Al-TA-LDH have typical structural characteristics of hydrotalcite. The interlayer spacing of Mg/Al-TA-LDH after intercalation is larger than that of Mg/Al-CO3-LDH prior to intercalation. Measurements of the thickening time and thickening curve of oil-well cement show that the slow release of tartaric acid has a retarding effect on the oil-well cement slurry mixed with the tartaric acid-intercalated hydrotalcite retarder, the effect is stable, and the thickening curve is stable and shows right-angle thickening. Based on the compressive strength test of oil-well cement, the strength increases gradually with the addition of 0.3%–1.0 % Mg/Al-TA-LDH promoting the development of 1 d and 3 d strength of stone cement. When the dosage of Mg/Al-TA-LDH is 1.0%, the 1 d and 3 d strength of stone cement is higher than that of pure cement, and the 3 d strength of stone cement is increased by 99.6%. The development of 7 d strength was inhibited, but the late strength development was still higher than that of pure cement, and the 14 d strength was 33.3% higher than that of pure cement. Tartaric acid-intercalated hydrotalcite can increase the thickening time of oil well cement through the release of tartaric acid, and can significantly improve the compressive strength of oil well cement through the seed promotion effect of hydrotalcite material.