Numerical study for removing wax deposition by thermal washing for the waxy crude oil gathering pipeline

Abstract

Exploring the wax removal process by numerical simulation is beneficial for guiding field operations. In this paper, enthalpy-porosity and volume of fluid (VOF) methods were adopted to simulate the melting process of wax in the crude oil gathering pipeline. The melting patterns and liquid fraction of the wax were used to validate the mathematical model. The results show that the wax melts quickly before the liquid fraction reaches 80%, while the remaining 20% melts very slowly. Since the water with higher density sinks to the lower part of the pipeline, the wax in the lower part of the pipeline melts first, while the wax in the upper part of the pipeline melts slowly. The water temperature and flow rate disproportionately affect the melting process. Increasing the water temperature and flow rate can accelerate the melting process, but the effects on shortening the melting time of wax gradually decrease. Increasing the flow rate, the heat transfer rate and the melting rate are increasing progressively, the change of flow rate also affects the outlet temperature of the pipeline.

Crude oil and the problem of wax deposition on pipeline systems during transportation: A review

“…Secondary nucleation involves the coming together of units of precipitates formed in the primary nucleation stage [3]. On reaching a certain stage, the formed wax crystals begin interacting with each other and begin to grow as time progresses until they become large enough to clog the pipe [14]. Anisuzaman et al [1] lists the various methods of ascertaining the physical parameters of waxy crude oil as are given in the table below:…”

“…These waxes cause lots of financial and technical damages and increase the costs of production [13]. It remains a critical operational challenge for the petroleum industry [14].…”

Numerical simulation of paraffin melting in circular tube using lattice Boltzmann method

“…Paraffin phase change process has wide and important applications in many fields, such as building energy saving, energy utilization, space exploration, pipeline paraffin removal and other fields [1][2][3][4][5]. Because of the wide melting temperature range and high latent heat of paraffin, the research on paraffin melting at domestic and foreign mainly focuses on the field of phase change materials, including the preparation methods of PCMs [6] and the improvement of solid-liquid phase-change heat transfer [7][8][9][10].…”

“…Ghosh et al [16] used the enthalpy porosity model in fluent software to simulate the solidification of paraffin in spherical cavity and rectangular cavity according to different thermal boundary conditions. Jiang et al [4] used enthalpy porosity and fluid volume (VOF) method to simulate the melting of paraffin in crude oil gathering and transportation pipeline. Li et al [17] established the mathematical model of phase change heat transfer and multiphase flow coupling problem, and studied the effects of water temperature, spherical paraffin size and initial temperature on paraffin melting and flow characteristics under natural convection conditions by using FLUENT software.…”

Impacto De Modelos De Difusão Molecular Na Previsão De Deposição De Parafina

“…No intuito de modelar os vários fenômenos físicos (dispersão por cisalhamento, difusão molecular, transferência de calor e massa) que podem influenciar o processo de formação, crescimento e envelhecimento do depósito de parafina (Van der Geest et al, 2021;Mehrotra et al, 2020;Merino-Garcia et al, 2007), um modelo matemático robusto é fundamental (Svendsen, 1993). A robustez do modelo necessariamente precisa ser capaz de resolver as equações de conservação (massa, quantidade de movimento, espécies e temperatura) com as equações constitutivas adequadas para a viscosidade e coeficiente de difusão molecular das espécies (Magnini e Matar, 2019;Jiang et al, 2020) e um modelo termodinâmico com equações de estado para determinar a precipitação (Coutinho et al, 2006b;Lira-Galeana et al, 1996). Fica claro que o desafio é grande, necessitando da definição de muitos modelos diferentes, além de ainda não se ter um consenso sobre quais os melhores modelos.…”