Research on erosion mechanism and life prediction of Underground protective tube in deep heavy oil recovery

Abstract Under the dual-carbon context, traditional heavy oil extraction methods exhibit limited effectiveness in deep heavy oil development. The downhole high-power electric heating steam extraction technology emerges as a novel approach for deep heavy oil production, which essentially involves deploying high-power electric heaters into steam injection wells for thermal recovery, thereby enhancing oil recovery by elevating steam dryness. In these steam injection wells, the annulus formed between the electric heater protective tube and the insulation tube’s inner wall is subject to prolonged steam erosion, yet the erosion patterns and the protective tube’s safety status remain unclear. Therefore, this paper meticulously analyzes the erosion mechanisms of high-temperature flowing steam on downhole protective tubes through Computational Fluid Dynamics (CFD) numerical simulations. It quantitatively assesses the effects of steam injection rate, steam dryness, steam temperature, protective tube dimensions, and particulate concentration on the erosion rate. The study reveals that the most severe erosion occurs in the area directly impacted by the injected steam jet. The erosion rate increases with steam injection rate, steam temperature, and particulate concentration, while it decreases with increasing steam quality and protective tube size. Among these factors, steam injection rate and particulate concentration exert the most significant influence on tube erosion. Furthermore, based on the erosion simulation results, a predictive model for protective tube erosion is established. Integrating the corrosion rate of the protective tube material and its high-temperature mechanical properties, a lifespan prediction method for the protective tube is proposed, yielding the tube’s lifespan under various erosion/corrosion coupling rates. The findings of this study offer valuable insights for safely exploiting deep heavy oil reserves using this novel technology in the field.