A new calculation method of shutdown and restart pressure of waxy crude oil pipeline

In order to obtain more accurate shutdown and restart pressure of waxy crude oil pipeline, a new calculation method is established on the basis of traditional start-up pressure calculation model. Referring to the Liu Tianyou start-up model, the restart pressure model is divided into three parts: pressure drop induced by elevation, pressure drop owing to inertia, and pressure drop owning to friction resistance. Considering the pressure drop caused by elevation difference along the pipeline, pressure drop owning to friction resistance is solved by regional discretization of pipeline. For part of pressure drop owning to friction resistance caused by thixotropic factor, the Houska thixotropy model which can better expresses the thixotropy of waxy crude oil is preferred. Using the new method, a corresponding calculation program is prepared and used for simulation with previous data of the Qinhuangdao-Beijing Oil Pipeline. The results obtained are in conformity with the practical ones, which indicate that the improved model is more accurate and applicable.