Preparation and properties of cationic polyacrylamide flocculant for drilling fluid based on modified nano SiO 2

SiO 2 particles of different particle sizes were prepared by sol–gel method using ethyl orthosilicate (TEOS) as raw material. Nano-silica/cationic polyacrylamide (S-CPAM) prepared by inverse emulsion polymerization of modified silica (C-SiO 2 ) as a hydrophobic component with acrylamide (AM), dimethyl diallyl ammonium chloride (DMDAAC) and Methacryloyloxyethyl trimethyl ammonium chloride (DMC). FT-IR, TEM, 1 H-NMR, SEM, TG, surface tension meter and twelve-speed rotational viscometer were used for characterization. The impact of C-SiO 2 particle size and content on the product properties was investigated. FT-IR and H-NMR tests were used to identify the structure and composition of the product. Scanning electron microscopy and surface tension tests showed that the introduction of C-SiO 2 increased the adsorption capacity of S-CPAM, and the critical association concentration (CAC) of S-CPAM was determined to be 1 g/L. Results showed that when the particle size of C-SiO 2 was 15 nm, the product had better water solubility, viscosity building and flocculation property. The flocculation, temperature, salt, shear resistance and ageing resistance of S-CPAM were assessed in relation to the C-SiO 2 content. The addition of C-SiO 2 improved the performance of the product, and the best performance was obtained for 0.7–1% of the monomer mass of added C-SiO 2 .