This study explored the potential of ultrafine kaolin as a geopolymer raw material, focusing on the reactivity of calcined kaolin products and its influencing factors. Through a series of analytical techniques, including thickening experiments, particle size analysis, SEM, XRD, and FT-IR, the effects of calcination temperature, time, and Si-Al ratio were evaluated. The results indicated that calcination temperature significantly impacts reactivity, with optimal conditions found between 600 °C and 800 °C, yielding metakaolin with thickening times of 12 to 43 min. Temperatures above 900 °C led to the formation of low-reactivity phases like mullite. The Si-Al ratio also influenced thickening time, with durations varying from 97 min at 0.85 to 43 min at 0.9 and increasing to 157 min at 0.95. Calcination time had the smallest effect, with thickening times ranging from 10 to 25 min over 4 to 8 h. Additionally, calcination altered particle size, initially expanding due to thermal expansion and later shrinking due to lattice distortion above 700 °C. By adjusting these parameters, the reactivity of calcined kaolin could be tailored to suit specific needs. This research provides a theoretical foundation for metakaolin’s application in construction materials and offers novel insights into geopolymer preparation.

Polymer additives in well cement slurry filtrate would affect the stability of natural gas hydrate (NGH), which could lead to formation collapse and cause marine disasters. It is necessary to clarify the critical conditions for the stability of NGH, i.e., NGH phase equilibrium. LAMMPS software and the TIP4P model were used to develop a method for calculating NGH phase equilibrium. Based on the single functional groups and combined functional groups of polymer additives, the potential energy, angular order parameter (AOP) of water molecules, and NGH phase equilibrium temperatures under different pressures were calculated, and a phase equilibrium curve was characterized. Results show that amide groups promote NGH decomposition more strongly than carboxyl and sulfonate groups, with a 1.5% dodecylamide system causing NGH phase equilibrium temperature to decrease by 1.68–2.77 K. AM/AA promotes NGH decomposition more strongly than AA/AMPSNa, AM/AMPSNa, and AA/AMPSNa/AM, with a 1.5% AM/AA system causing NGH phase equilibrium temperature to decrease by 2.33–3.56 K. To ensure the safety of well cementing and marine environments, the contents of amide groups and carboxyl groups should be reduced when developing polymer additives for cement slurry used in NGH formation cementing.