The process of deposition of paraffin causes great financial losses to the oil industry. Therefore, studies aimed at predicting the formation of paraffin deposits is one of the main topics of study to assure the flow. The oil while still inside the reservoir is in equilibrium at high temperature [approximately 60 degrees Celsius] with the paraffin dissolved in the oil. However, with the beginning of production, the oil is transported through pipelines of hundreds of kilometers, often in deep waters where the temperature are low [approximately 4 degrees Celsius]. The solubility of paraffin in low temperatures is reduced, so the paraffin leaves the solution and diffuses towards the walls of the tubing, where it deposits, blocking the passage of oil. Thus, this paraffin deposit decreases well productivity and increases costs with measures to remedy the problem, such as the use of it pigging operation, ie, passage of equipment called PIG for the removal of deposits. The present work aims to investigate the influence of natural convection on the determination of deposit thickness in horizontal annular ducts using Ansys CFX commercial software. The deposition process considered consists in assuming that the oil behaves like a Bingham fluid, with temperature-dependent yield stress. It was verified thicker deposit thickness at the inferior part of the annulus, where the fluid is cooler due to the natural convection effect, agreeing the experimental data.