Solid Particle Deposition During Turbulent Flow Production Operations (original) (raw)
Related papers
Prefouling Behavior of Suspended Particles in Petroleum Fluid Flow
SCIENTIA IRANICA, 2010
The production and transportation of petroleum uids will be severely aaected by the deposition of suspended particles (i.e. asphaltenes, diamondoids, paraan/wax, sand, etc.) in petroleum uid production wells and/or transfer pipelines. In certain instances, the amount of precipitation is rather large causing complete fouling of these conduits. Therefore, it is important to understand the behavior of suspended particles during petroleum uid ow conditions. In this paper, we present an analytical model for the prefouling behavior of suspended particles corresponding to petroleum uids production conditions. We predict the rate of particle deposition during various turbulent ow regimes. The turbulent boundary layer theory and the concepts of mass transfer are utilized to model and calculate the particle deposition rates on the walls of owing conduits. The developed model accounts for the eddy diiusivity and Brownian diiusivity as well as for inertial eeects. The analysis presented in this paper shows that rates of particle deposition (during petroleum uid production) on the walls of the owing channel due solely to diiusional eeects are small. It is also shown that deposition rates decrease with increasing particle size. However, when the process is momentum controlled (large particle sizes), higher deposition rates are expected.
Asphaltene and Other Heavy-Organic Particle Deposition During Transfer and Production Operations
Proceedings of the 1995 SPE Annual Technical Conference and Exhibition, 1995
The production and transportation of petroleum fluids could be severely affected by deposition of suspended particles (i.e. asphaltene, paraffin/wax, sand and/or diamondoids, in the production wells and/or transfer pipelines. In many instances the amount of precipitation is rather large causing complete plugging of these conduits. Therefore, it is important to understand the behavior of suspended particles during flow conditions. In this paper we present an overview of the heavy organics deposition problem, its causes, effects and preventive techniques. We also present an analysis of he diffusional effects on the rate of solid particles deposition during turbulent flow conditions (crude oil production generally falls within this regime). We utilize the turbulent boundary layer theory and the concepts of mass transfer to explain the particle deposition rates on the walls of the flowing conduits e developed model accounts for the Brownian and eddy diffusivities as well as for inertial effects and other forces acting upon the particles. The analysis presented in this paper shows that rates of particle deposition (asphaltene, paraffin/wax, sand and/or diamondoids) on the walls of the flowing channels due solely to diffusional effects, are negligible. It is also shown that deposition rates decrease with increasing particle size. However, when the deposition process is momentum controled (large particles) higher deposition rates are predicted. It is shown a decrease in deposition rates with increasing crude oil kinematic viscosity. An increase in deposition rates with increasing production rates is also observed.
International Journal of Heat and Mass Transfer, 2020
The deposition of asphaltene, wax, hydrates, scale, and even transfer of sands in oil wells and pipelines are serious problems that cause production interruptions and lead to substantial economic losses. The present study opens a new window for solving this unresolved problem. Accordingly, an improved Eu-lerian deposition model that incorporates various mechanisms of particle transport and deposition (e.g., molecular and turbulent diffusion, turbophoresis, thermophoresis, and surface roughness) was extended to predict solid deposition in oil wells. In this paper, to make it possible to predict deposition in inclined and horizontal pipes, the model was modified to include the gravitational settling effect. Moreover, using this model, a new method was proposed to determine the particle size distribution and particle floccu-lation function. It was first validated by predicting particle deposition in turbulent airflow and showed very good agreement with a wide range of published observation data. Then the model was used for predicting the thickness profile of asphaltene deposition in two laminar flow capillary tube experiments reported in the literature. This model, for the first time, has predicted asphaltene deposition profiles with high accuracy, especially without the use of empirical parameters. The predictions of this model are as accurate as particle tracking methods but at much lower computational costs. This study demonstrates that under certain conditions in laminar flow, deposition is dominated by gravitational settling, while it has been hypothesized previously that asphaltene deposition predominantly occurs by diffusion. The results reveal that particle size distribution plays a vital role in asphaltene deposition modeling. The findings of this study can help for a better understanding of the effective mechanisms of asphaltene deposition. This is the most versatile theory that can be adapted with various flow conditions. Since this approach does not depend on the solid type, it can be similarly applied to predict the behavior of other solid-fluid flow assurances in oil and gas facilities. Modeling the solid solution and multi-solid phase behavior are other capabilities of the developed methodology. The high accuracy of this approach and using minimum adjustable parameters offer many avenues for future development to evaluate particle deposition in real field applications.
Petroleum, 2016
The deposition of asphaltenes on the inner wall of oil wells and pipelines causes flow blockage and significant production loss in these conduits. The major underlying mechanism(s) for the deposition of asphaltene particles from the oil stream are still under investigation as an active research topic in the literature. In this work, a new deposition model considering both diffusional and inertial transport of asphaltene toward the tubing surface was developed. Model predictions were compared and verified with two sound experimental data available in the literature to evaluate the model's performance. A parametric study was done using the validated model in order to investigate the effect of the asphaltene particle size, flow velocity and oil viscosity on the magnitude of asphaltene deposition rate. Results of the study revealed that increasing the oil velocity causes more drag force on wall's inner surface; consequently, particles tend to transport away from the surface and the rate of asphaltene deposition is decreased. In addition, the developed model predicts that at low fluid velocity (~0.7 m/s), the less viscous oil is more prone to asphaltene deposition problem.
ANALYTICAL AND CFD INVESTIGATION OF TURBULENT DIFFUSION MODEL FOR PARTICLE DISPERSION AND DEPOSITION
Journal of Mechanical Engineering, 2009
A 2D analytical turbulent diffusion model for particle dispersion and deposition at different heights across the pipe flow and circumferential deposition has been developed. This liquid-solid turbulent diffusion model presented in this paper has emanated from an existing gas-liquid turbulent diffusion model. Simultaneously a comprehensive 3D numerical investigation has been carried out to study the above making of multiphase mixture model available in Fluent 6.1. In both studies different particles sizes and densities were used. The deposition was studied as a function of particle diameter, density and fluid velocity. The deposition of particles, along the periphery of the wall and at different depths, was also investigated. Both studies showed that the deposition of heavier particles at the bottom of the pipe wall was found to be higher at lower velocities and lower at higher velocities. The lighter particles were found mostly suspended with homogeneous distribution. Smaller particles were also suspended with marginal higher concentration near the bottom of the wall. This marginal higher concentration of the smaller particles was found to be slightly pronounced for lower velocity. The larger particles clearly showed deposition near the bottom of the wall. These analogies of particles are well discussed with the ratio between free flight velocity and the gravitational settling velocity.
Deposition of particles in a turbulent pipe flow
Abstrac~Effects of flow direction, nonlinear drag and the corrected lift force on particle deposition rate in turbulent pipe flow is studied. A digital simulation technique is used and the trajectories of particles of different sizes are analyzed. The experimental data for the mean flow field and the intensities of fluctuation velocity components are used in the analysis, and the effects of turbulent diffusion and Brownian dispersion are included in the computational model. The instantaneous turbulent fluctuation is simulated as a continuous Gaussian random vector field and the Brownian force is modeled as a Gaussian white-noise random process. Ensembles of particle trajectories are evaluated and statistically analyzed. It is shown that the simulation results for the deposition velocity are in reasonable agreement with the model predictions, the available experimental data, and the recent simulation results for channel flows. It is shown that the downward gas flow in a vertical pipe enhances the particle deposition rate, while the upward flow reduces it. © 1997
Effect of Fluid Viscosity on Asphalthene Deposition Rate during Turbulent Flow in Oil Wells
American Journal of Chemical Engineering , 2013
The production and transportation of petroleum fluids will be severely affected by the deposition of suspended particles (i.e. asphaltenes, diamondoids, paraffin/wax, sand, etc.) in petroleum fluid production wells and/or transfer pipelines. Viscosity variations of petroleum fluid are an important phenomenon that could have significant effect on different properties related to petroleum fluid. Therefore, it is important to understand the effect of viscosity variations of petroleum fluid on the deposition rate of suspended particles on the walls of the flowing channel. In this study, the analytical model for the prefouling behavior of suspended particles in production lines is challenged in terms of viscosity changes that occur during the production in oil wells/tubings for a typical fluid sample experiencing particle deposition. Calculations of particle deposition rate in oil wells/tubings considering the change in viscosity for this typical oil sample is taken into consideration. The analysis presented in this report shows that rates of particle deposition (during petroleum fluid production) on the walls of the oil well/tubing is slightly affected by the viscosity variations that occur during the production conditions. It is also shown that the assumption of constant viscosity, while deriving the analytical model for the deposition rate of particles on the walls of fluid conduits, is quite a reasonable and valid assumption.
Particle deposition from turbulent flow in a pipe
Journal of Aerosol Science, 1998
Diffusive particle deposition rates are predicted on the walls of a straight, smooth circular tube in which fully developed turbulent flow exist. As a pre-requisite to calculating particle wall flux, the particle mass balance equation (convective diffusion) is solved, using the method of separation of variables. A sub-layer model is used, in which a thin laminar sub-layer is considered to be imbedded within the turbulent boundary layer. In the region outside the laminar sub-layer, the time-averaged transport of particles to the wall is enhanced because of the turbulence induced eddy-diffusivity of the particles. Inside the laminar sub-layer close to the wall, the effect of turbulence is considered negligible and transport of particles to the surface is dominated by particle Brownian diffusivity. Using method of separation of variables, the problem is reduced to one of solving an ordinary differential equation which belongs to the Sturm-Liouville class of equations. We compute and report the first ten eigenvalues and associated eigenfunctions of the reduced equation along with the relevant constants needed to estimate the evolving particle number density profile and timeaveraged particle wall deposition rates. Particle deposition rates have been estimated for Reynolds numbers and particle Schmidt numbers ranges of greatest practical interest. Asymptotic eigenvalues are reported and are seen to be in good agreement with the computed values. Application of the results to estimate the inertial contribution to the particle deposition rates in the eddy diffusionimpaction regime is also illustrated and generalizations of our methods have been discussed. 0 1998 Published by Elsevier Science Ltd. All rights reserved a* a' c C" D
Environmental Modeling & Assessment, 2011
A 2D analytical turbulent diffusion model for particle dispersion and deposition at different heights along the pipe flow and circumferential deposition has been developed. This liquid–solid turbulent diffusion model presented in this paper has emanated from an existing gas–liquid turbulent diffusion model. This model can be used as a handy tool for quick estimation one and two-dimensional deposition fluxes of particles in water distribution networks. A comprehensive 3D numerical investigation has been carried out using multiphase mixture model available in “Fluent 6.2” to verify the above analytical model. Different particles sizes and densities were used for 3D numerical investigations. The deposition was studied as a function of particle diameter, density, and fluid velocity. The deposition of particles, along the periphery of the pipe wall and at different depths, was investigated. Both the models findings matched with qualitative phenomena such as deposition of heavier particles at the bottom of the pipe wall were higher at lower velocities and lower at higher velocities. The lighter particles were found mostly suspended with homogeneous distribution. Smaller particles were also suspended with marginal higher concentration near the bottom of the pipe wall. This marginal higher concentration of the smaller particles was found to be slightly pronounced for lower velocity. These analogies of particles are well discussed with the ratio between free-flight velocity and the gravitational settling velocity. Extended analytical model results were compared with the 3D computational fluid dynamics simulation results. Discrepancies in the model results were discussed.
The dependence of particle deposition velocity on particle inertia in turbulent pipe flow
Journal of Aerosol Science, 1976
A~traet-Recent measurements of particle deposition velocities on the walls of a pipe in turbulent flow (Liu and Agarwal, 1974) show a decline with increasing particle size beyond a critical particle size. A stochastic model of particle deposition is presented which explains this result. As in other models, the deposition process is composed of turbulent diffusion, together with inertial projection through the boundary layer; in this model, both processes are particle inertia dependent, in opposing ways. The observed decline is due to the increased fractional penetration of the boundary layer with increasing particle size being insufficient to compensate for the reduced rate of transport to that region. A simple expression is given for the particle deposition velocity in terms of the r.m.s, velocity at that point and the fractional penetration of the boundary layer. The inertial dependence of the particle velocity is expressed in terms of the particle's response to the turbulent velocity fluctuations of its neighbouring fluid by relating the velocity spectral densities of the particle and fluid using a linear dimensionless form of the equation of motion of the particle. The fractional penetration of the boundary layer is based on Stokes' drag with a quiescent fluid. The deposition profile shows good agreement with the experiments of Liu and Agarwal.