Preparation and performance of oil well cement fluid loss additive ANAFM

The organic/inorganic fluid loss additive was prepared by using silane coupling agent KH-550 modified nano silica as auxiliary material and 2-acrylamido-2-methylpropanesulfonic acid (AMPS), N-vinylpyrrolidone (NVP), Acrylamide (AM), Fumaric acid (FA) as the comonomer. The ideal reaction conditions of the copolymer were confirmed to be the reaction temperature was 65 °C, the reaction time was 6 h, the mass ratio of AMPS/AM/NVP/FA was 4:4:1:1, and the amount of initiator was 0.36 wt%. Fourier transform infrared (FTIR) spectroscopy and thermogravimetry-differential thermal analysis (TG-DTA) were used to characterize the resulting copolymer, and its morphology was studied. TG test results confirmed that the copolymer has good thermal resistance, which can be found at 229 °C to maintain the thermal stability of the macromolecular chains; GPC results indicated that the number average molecular weight (Mn) of the polymer was 11.08 × 104 g/mol, the fluid loss additive ANAFM has good filtration performance, and the API filtration of oil well cement is 46 mL at 130 °C with 5% ANAFM. The scanning electron microscopy (SEM) results show that ANAFM could adsorb on the surface of cement particles to form a hydration layer, which prevented leakage of oil well cement slurry.