<p>High temperature and pressure are the main challenges faced in the exploration of deep earth sciences. In order to ensure the safe drilling of high-temperature and high-pressure wells, a thick-walled simulated wellbore device is proposed and its heat transfer characteristics are studied according to the test requirements of pressure bearing exceeds 25 MPa and temperature exceeds 673.15 K. To investigate the dynamic heating process of the fluid within the cylinder, a mathematical model was developed to describe the coupled heat transfer mechanisms. This model incorporates the nonlinear properties of the fluid inside the cylinder.</p><p>The results reveal that the temperature field distribution during the dynamic coupling heat transfer process is influenced by the electromagnetic induction current and the internal flow within the cylinder. During heating, the liquid transitions from a subcritical to a supercritical state. Buoyancy arising in the heating process affects the temperature distribution within the container and the formation of vortices. Incorporating a cooling system at the top of the container effectively maintains low-temperature operation in the sealing area. Additionally, the study shows that higher currents significantly increase both the final average liquid temperature and the cylinder wall temperature compared to the initial conditions. The proposed model and solution methodology provide a reliable approach for simulating fluid-structure coupled heat transfer in high-temperature, high-pressure well environments, offering a theoretical foundation for designing simulated wellbore heating systems.</p>