Thermal Simulation of an Underground Oil Pipeline at Startup

Water preheating is necessary to avoid oil freezing in the pipeline when the viscid and wax oil start to be transported. The regular and backpumping can be used in the process of preheating. The oil can be transported when the pipeline temperature is up to a certain value and the heat is stored in the soil around the pipeline. The process of preheating is an unsteady heat transfer of three dimensions. The physical model of the pipeline and the soil around the pipeline was simplified and a numerical model was established and solved by the finite difference method. The measured data of the pipeline and the calculation results were used for verification. Numerical simulation results are consistent with the theoretical calculation results, and then it can provide theoretical references to reasonable arrangement for pipeline at start-up.