Abstract: In order to evaluate the applicability of each scaling prediction method to oil and gas wells in Xihu Sag, theoretical calculation and software simulation methods were used to analyze the scaling of Well C11 under three conditions: single production of formation water, single injection of seawater, and mixing of seawater and formation water. By comparing the actual data, Scalechem software has greater applicability in mixed scaling prediction of oil and gas wells in Xihu Sag. In terms of single calcium carbonate scaling prediction, Ryznar method is more accurate. In terms of single sulfate scaling prediction, Skillman method matches the actual situation. It is analyzed that the wellbore scaling of Well C11 is mainly caused by formation outflow, and the scaling type is mainly CaCO₃. The offshore wellbore anti-scaling technology was discussed, aiming to provide technical support for the effective treatment of oil and gas wells scaling problems in Xihu Sag.