Development and mechanism of a multi-target adsorption high-temperature-resistant filtrate reducer: Synergistic effects of Si–O–Si chemical bonds and ionic interactions

Deep and ultra-deep drilling operations face significant challenges such as high temperatures and salinity levels. Drilling fluids are prone to failure under these conditions, causing increased filtration loss and frequent downhole accidents. To address these critical issues, this study utilised the high-temperature-stable adsorption properties of siloxanes to synthesise a multi-target adsorption-type fluid filtrate reducer, PFS-1. The molecular structure and thermal stability of PFS-1 were characterised using 1 H NMR, Fourier transform infrared spectroscopy and thermogravimetric analysis. Its effects on the microstructure of drilling fluid were investigated using scanning electron microscopy, X-ray diffraction and zeta potential analysis, thereby elucidating the interaction mechanism between PFS-1 and clay particles. Experimental results demonstrate that PFS-1 possesses excellent thermal stability, with a decomposition onset temperature exceeding 318°C. After thermal ageing at 240°C for 16 h and 72 h, the filtration loss of drilling fluid containing 2 wt% PFS-1 was 9.1 mL and 9.7 mL, respectively. Additionally, in a 15 wt% NaCl brine-based drilling fluid system, the API filtration loss was just 5.6 mL after ageing at 220°C with 2 wt% PFS-1. Results confirm the superior high-temperature resistance and salt tolerance of the novel filtration reducer. Through the synergistic effect of Si–O–Si chemical adsorption and ionic bonding, PFS-1 forms a stable multi-point adsorption on the surface of the clay particles, inhibiting their hydration and aggregation and thereby reducing the fluid filtration loss. Furthermore, the performance of PFS-1 was improved by 18.75 % compared to that of commercial products, indicating its strong potential for application in demanding drilling environments characterised by ultra-high temperatures and high salinity.