Heavy oil reservoirs represent an important resource for alleviating energy shortages and supporting global economic development. This investigation explores the influence of a nano vanadium acid catalyst (NVR) and reservoir conditions including temperature, pressure, and shear rate on the apparent viscosity and rheological properties of crude oil during the underground extraction process. NVR was synthesized by loading vanadate active groups onto nano-SiO$_2$ particles via hydrothermal reaction. The results indicate that 0.3~wt% NVR achieves a maximum viscosity reduction rate of 60%, significantly outperforming the commercially available viscosity reducer CVR under identical conditions. Amo... More >