Modeling of the process of formation and prevention of asphaltene sediments

Abstract

Copyright © 2019 American Scientific Publishers All rights reserved The paper discusses the use of mathematical models and calculations by means of computer simulation to determine the process of formation of asphaltene sediments in pipelines. The influence of various factors on formation of sediments from paraffinic oil is considered by creating a modeling scheme for the formation of sediments of asphalt-resin-paraffin substances in pipelines with the use of the Aspen HYSYS software environment and the DepoWax module of the PVTSim 19 software package, as well as an assessment of the effectiveness of individual solvents and their mixtures. The main criterion to predict the formation of sediments of asphalt-resin-paraffin substances based on different approaches is the excess of the temperature of oil saturation with paraffin temperature. It is established that the change in the thickness of the sediments, depending on the temperature of the input stream, is non-linear. The maximum thickness of sediments with increasing initial oil temperature shifts from 2000 m to 3000 m. The results show that the dependence of the change in the flow temperature along the pipe length is described by a hyperbolic curve and, starting from 4000 m, remains almost constant and the same until the end of the pipeline. Dominating influence in this case belongs to a temperature gradient along the tube length: the higher the gradient value is, the thicker sediments at the maximum point. Regression equations were obtained for predicting the viscosity of oils at various temperatures and concenrations of depressants with the use of the viscosity additivity property for better understanding the processes which occur upon transporting a mixture of oils of different viscosity inside a pipeline system.