One of the major problems in using underwater pipelines that transports paraffinic oil is the flow restart after a possible stop in production. After a period of interruption, the oil modified their rheological properties because of the precipitation of wax molecules, forming a gel microstructure. The viscoplastic behavior of the oil at low temperatures is his main rheological characteristic. To restart the flow is necessary a high pressure, above the normal operation of the pipeline. For this, the duct is usually fed with another fluid and pumped with the minimum pressure necessary for the resumption of the flow. It is, therefore extremely important to determine the necessary pressure for the definition of the power and hence the dimensioning of the pump of the pipeline. In this paper, we use the Herschel-Buckley model of viscosity, through a numerical simulation, to analyze the major influences on the behavior of the fluid, through the use of different maximumshear stress and different geometries, determining in the end, all quantities inherent to this phenomenon.