Synthesis, performance evaluation and retarding mechanism study of ultra-high temperature retarding agent for cementing slurry.

Aiming at the problem that the current retarding agent has poor temperature resistance and poor high-temperature retarding performance, which is easy to lead to sudden thickening of the cement slurry at high temperatures, thus affecting the cementing construction and cementing quality, this study introduced sulfonic acid, imidazole ring, and carboxylic acid adsorption group to prepare an ultra-high temperature retarding agent (UHTR). The synthesis conditions were determined by the response surface optimization method. The structure of UHTR was characterized by FT-IR and 1 H NMR spectrum. The effect of UHTR on the properties of cement slurry was studied through the thickening and fluidity experiment. The impact of UHTR on the strength of the cement stone was tested. The retardation mechanism was studied using XPS, TGA, XRD and SEM. The results showed that UHTR had good thermal stability, with no significant weight loss at temperatures below 320 ℃; UHTR exhibited excellent high-temperature retardation performance, with a thickening time of 251 minutes at 220 ℃ with a 1.5 % dosage, a stable and right-angle thickening curve; at 240 ℃, the 24 h compressive strength of the cement stone reached 22.5 MPa. In addition, UHTR had a low temperature and low dosage sensitivity, which can meet the cementing construction requirements for high-temperature wells. Mechanism analysis indicated that the sulfonic acid groups and imidazole ring groups in UHTR jointly enhanced the thermal stability of the molecule, and the sulfonic and carboxyl groups exerted a retarding effect by adsorbing on the surface of cement particles and chelating Ca2+ in the cement slurry. UHTR can maintain good thickening properties of the cement slurry at 220 ℃, which is significant for the smooth implementation of ultra-deep well cementing operations and improving cementing quality. [Display omitted] • UHTR is a cementing retarder suitable for ultra-high temperature conditions. • UHTR can adjust the thickening time of cement slurry by dosage. • UHTR has little impact on the strength development of cement stone. • UHTR has low temperature sensitivity and stable performance at 160 ∼ 220 ° C. • UHTR molecules contain imidazole rings, sulfonic acid, and carboxylic acid groups. [ABSTRACT FROM AUTHOR]