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Wax deposition modeling in oil-water stratified pipe flow

Petroleum Science 2023年第1期20卷 526-539页

作者： Hui-Shu Liu Ji-Miao Duan Jiang Li Jian Wang Hao Yan Ke-Yu Lin Ke-Cheng Gu Chang-Jun Li Petroleum Engineering School Southwest Petroleum UniversityChengdu610500China Petroleum Oil and Lubricants DepartmentArmy Logistics AcademyChongqing401311China

Wax deposition in oil-water Stratified flow is commonly encountered onshore and offshore oil production pipe systems,and typically reduces transportation capacity of oil.The accurate predicted model of wax deposition has becomes an indispensable approach to design effective remediation strategies.However,a reliable mechanistic model for wax deposition prediction in oil-water two-phase stratified pipe flow is lacking to validate the deposition process.In this work,a three-dimensional(axial,radial,and angular)robust wax deposit model for oil-water stratified circular pipe flow was developed.The model of formation of a gel deposit based on the first principles of rheology was developed,associated with the results obtained from hydrodynamics and heat/mass transfer simulations.The predictions for wax deposition are found to compare satisfactorily with experimental data with two different oils for single phase and four different water cuts for oil-water stratified pipe flow.It can be seen from the wax gelation mechanism that an increase in water cut can help to reduce the wall/oil-deposit interface shear stress,thereby leading to an increase in the degree of gelation as well as the deposit rate.Furthermore,a local deposit analysis in the circumferential direction was conducted,for water cut 75%and total flow rate 5 m3/h,which provided insights to understand that the thickness on pipe wall was roughly uniformly distributed locates near the top of the pipe and the nearer the position gets close to two points,where the oil-water interface contacts the inner wall,the deposition thickness quickly dropped to 0.It was attributed to the fact that a roughly uniformly thickness far away from the oil-water interface contact the inner wall resulted in the slowly changes temperature along the circumferential pipe wall wetted by oil.

关键词： Wax deposition Oil-water flow Stratified flow Heat and mass transfer

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New turbulence modeling for air/water Stratified flow

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Journal of Ocean Engineering and Science 2020年第1期5卷 55-67页

作者： M.Ghafari M.B.Ghofrani Department of Energy Engineering Sharif University of TechnologyAzadi Ave.TehranIran

The prediction of interfacial turbulence characteristics is one of the still challenging of two-phase Stratified flow.The evaluation of some important parameters such as interfacial heat transfer coefficient based on turbulence kinetic energy and turbulence dissipation rate in some models,intensifies the importance of turbulence flow correct simulation.High gradient of velocity and turbulence kinetic energy at the interface of two-phase Stratified flow leads to a major overestimation or underestimation of flow characteristics without any special treatment.Consideration of a source function of turbulence eddy frequency at the interface is one of the common solution employed in past researches.Although this solution remedies some shortcomings of traditional methods in smooth Stratified flow,its application in wavy Stratified flow needs the other modifications.The examination of turbulence characteristics near the free surface reveals that,in addition to turbulence eddy frequency,the other source function of turbulence kinetic energy should be considered near the free interface.So,a new source function of turbulence kinetic energy is proposed at the interface based on flow condition.This new method has been employed for Fabre et al.(1987)experiment designed for air/water Stratified flow.The results of simulation have a good agreement with experimental data and turbulence characteristic can be captured near the free surface.

关键词： Stratified flow Turbulence model Turbulence kinetic energy Source function

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Non-symmetric distributions of solids deposition for solid-water Stratified flow in deviated tubing strings

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Petroleum Science 2023年第5期20卷 3048-3061页

作者： Xin-Fu Liu Chun-Hua Liu Zhong-Xian Hao Ying Zheng Kai Zhang Jian-Feng Wang Song-Bo Wei Ai-Gang Hao Jun-Ling Tao Hui Cheng School of Mechanical and Automotive Engineering Qingdao University of TechnologyQingdaoShandong266520China College of Mechanical and Electronic Engineering China University of Petroleum(East China)QingdaoShandong266580China Research Institute of Exploration&Development PetroChinaBeijing100083China Department of Chemical and Biochemical Engineering Western UniversityOntarioN6A 3K7Canada Lusheng Petroleum Development Company Ltd. SINOPECDongyingShandong256657China

Dynamic performance on solids flow with water in deviated tubing is essential for the reliability of pump and normal operation of horizontal and directional wells.Compared with coal-water flow in vertical tubing and sand-oil flow with high production in deviated tubing,solids deposition with water shows obvious non-symmetric distributions in deviated tubing from simulations and experiments.The mathematical model of two phase flow was developed under coupling conditions of deviated tubing,low flow rate and viscosity based on the kinetic theory of granular flow and first-order discrete scheme.The results show that solid-water Stratified flow in deviated tubing can be divided into two zones of suspension bed and the moving bed throughout the flow field.The solid flowing velocity with water is negative and particles slide down at the bottom of moving bed zone.The process of solids flow with water in deviated tubing will produce pressure loss and consume the kinetic energy.The thickness of deposited layer and the flowing velocity of solids flow downward with water at the moving bed zone enhance with the decreased inlet flow rate and the increased particle size,tubing inside diameter(ID)and inclination angle.Solids are easier into suspension from the upper part of moving bed zone to suspension bed zone and more solid particles flow with water towards the tubing outlet with the increase of inlet flowing velocity.The decision is made to reduce the screen width,tubing ID and inclination angle to maintain to be greater than critical deposition velocity in order to prevent solids settling.And it provides the theoretical basis and technical reserves for solid control and offers an effective approach to enhance tubing cleaning in deviated strings.

关键词： Deviated tubing Stratified flow Solid deposition Critical velocity Prevent solids settling

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A NONHYDROSTATIC NUMERICAL MODEL FOR DENSITY Stratified flow AND ITS APPLICATIONS

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Journal of Hydrodynamics 2008年第6期20卷 706-712页

作者： LI Qun XU Zhao-ting Polar Research Institute of China （PRIC） Shanghai 200136 China Physical oceanography Institute Ocean University of China Qingdao 266100 China

A modular numerical model was developed for simulating density-Stratified flow in domains with irregular bottom topography. The model was designed for examining interactions between Stratified flow and topography, e.g,, tidally driven flow over two-dimensional sills or internal solitary waves propagating over a shoaling bed. The model was based on the non-hydrostatic vorticity-stream function equations for a continuously stratified fluid in a rotating frame. A self-adaptive grid was adopted in the vertical coordinate, the Alternative Direction Implicit （ADI） scheme was used for the time marching equations while the Poisson equation for stream-function was solved based on the Successive Over Relaxation （SOR） iteration with the Chebyshev acceleration. The numerical techniques were described and three applications of the model were presented.

关键词： nonhydrostatic assumption Stratified flow self-adaptive grid nonlinear internal wave

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Gas-water Stratified flow patterns from electromagnetic tomography

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Petroleum Science 2009年第3期6卷 254-258页

作者： Wang Xiaoxing Wu Xiling School of Resources and Information Technology China University of Petroleum Beijing 102249 China

Because of gravitational differentiation of multi-phase fluids, gas-water flow is usually stratified in highly inclined or horizontal gas wells. By using electrode arrays to scan flowing fluids, electromagnetic tomography can identify the flow patterns of mixed fluid from the different electrical properties of gas and water. The responses for different gas-water interface locations were calculated and then physical measurements were undertaken. We compared the results of the numerical simulation with the experimental data, and found that the response characteristics were consistent in the circumstances of uniform physical fields and Stratified flows. By analyzing the signal characteristics, it is found that, with the change of the interface location, the response curves showed ＂steps＂ whose position and width were decided by the location of fluid interface. The measurement accuracy of this method depended on the vertical distance between adjacent electrodes. The results showed that computer simulation can simulate the measurement of the electromagnetic tomography accurately, so the physical experiment can be replaced.

关键词： Electromagnetic tomography Stratified flow gas-water numerical simulation physical experiment

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STABILITY OF DENSITY Stratified flow IN THE BOUNDARY LAYER

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Journal of Hydrodynamics 2006年第5期18卷 505-511页

作者： XIE Ming-liang LIN Jian-zhong State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China China Jiliang University Hangzhou 310018 China

The stability of the laminar flat plate boundary layer is investigated numerically by solving the linear Orr-Sommerfeld equations for the disturbulence amplitude function. These equations include the terms of viscosity, density stratification, and diffusion. Neutral stability curve and the critical Re numbers are computed for various Richardson （Ri） numbers and Schmidt （Sc） numbers. The results show that the larger the Ri, the larger the critical Re for Sc 〈 10. The flow is stable for Ri 〈 0, when Sc is very small or the mass diffusion coefficient is very large. But for Ri 〉 0, the effects of diffusion are reversed for Sc 〈 10. For Sc 〉 10, the critical Re rapidly decreases to zero as the Sc increases for a given Ri number. The critical Re rapidly decreases as the Ri increases.

关键词： stability Stratified flow boundary layer blasius flow

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Precessing motion in stratified radial swirl flow

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Chinese Journal of Aeronautics 2016年第2期29卷 386-394页

作者： Qin Hao Lin Yuzhen Li Jibao National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics School of Energy and Power Engineering Beihang University AVIC Commercial Aircraft Engine Co. Ltd.

Vortex/flame interaction is an important mechanism for unsteady combustion in a swirl combustion system. Technology of low emission stirred swirl （TeLESS）, which is characterized with stratified swirl flow, has been developed in Beihang University to reduce NOx emission. However, large-scale flow structure would be induced in strong swirl flow. Experiments and computational fluid dynamics （CFD） simulation were carried out to investigate the unsteady flow feature and its mechanism in TeLESS combustor. Hotwire was firstly applied to testing the unsteady flow feature and a distinct mode with 2244 Hz oscillation frequency occurred at the pilot swirl outlet. The flow mode amplitude decayed convectively. Large eddy simulation （LES） was then applied to predicting this flow mode and know about its mechanism. The deviation of mode prediction compared with hotwire test was 0.8%. The spiral isobaric structure in pilot flow passage indicates that precessing vortex core （PVC） existed. The velocity spectrum and phase lag analysis suggest that the periodic movement at the pilot outlet was dominated by precessing movement. Negative tangen- tial momentum gradient reflects that the swirl flow was unstable. Another phenomenon was found out that the PVC movement was intermittently rotated alon~ the symmetric axis.

关键词： Large eddy simulationPrecessing motion Stratified flow Swirl flow Unsteady flow

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Numerical Simulation on Stratified flow over an Isolated Mountain Ridge

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Tsinghua Science and Technology 2007年第3期12卷 332-336页

作者：李玲 Shigeo Kimura State Key Laboratory of Hydroscience and Engineering Department of Hydraulic EngineeringTsinghua University Institute of Nature and Environmental Technology Kanazawa UniversityKanazawa 920-8667Japan

The characteristics of Stratified flow over an isolated mountain ridge have been investigated numerically. The two-dimensional model equations, based on the time-dependent Reynolds averaged Navier- Stokes equations, are solved numerically using an implicit time integration in a fitted body grid arrangement to simulate Stratified flow over an isolated ideally bell-shaped mountain. The simulation results are in good agreement with the existing corresponding analytical and approximate solutions. It is shown that for atmospheric conditions where non-hydrostatic effects become dominant, the model is able to reproduce typical flow features. The dispersion characteristics of gaseous pollutants in the Stratified flow have also been studied. The dispersion patterns for two typical atmospheric conditions are compared. The results show that the presence of a gravity wave causes vertical stratification of the pollutant concentration and affects the diffusive characteristics of the pollutants.

关键词： internal gravity wave Stratified flow complex topography numerical method

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Prediction of pressure gradient and hold-up in horizontal liquid-liquid pipe flow

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Petroleum Science 2023年第6期20卷 3766-3782页

作者： Syed Amjad Ahmed Bibin John School of Mechanical Engineering Vellore Institute of TechnologyIndia Department of Mechanical Engineering C Abdul Hakeem College of Engineering&TechnologyIndia

This paper aims to propose correlations to predict pressure gradient,friction factor and fluid phase hold-up in liquid-liquid horizontal pipe flow.To develop the correlations,experiments are conducted using high viscous oils(202 and 630 mPa⋅s)in a steel pipe of length 11.25 m and length-to-diameter ratio of 708.In addition,the experimental data from the literature comprising wide range of flow and fluid properties is analyzed.For the analysis,the liquid-liquid pipe flow data is categorized into two as:stratified and dispersed.The existing friction factor correlations are modified to incorporate the effects of viscosity of the oil phase,interfacial curvature(contact/wetting angle-in lieu of material of the pipe)and fluid phase fraction.In the two-fluid model of Stratified flow,the wall stress and interfacial stress correlations are substituted with superficial velocities of fluids and superficial Reynolds numbers of fluid phases replacing fluid phase velocities and fluid Reynolds numbers.Similarly,for dispersed flow,an effective Reynolds number is described as the sum of superficial Reynolds number of oil and water phases.Substituting the generally employed mean or mixture Reynolds number with the effective Reynolds number into the existing single-phase turbulent flow friction factor correlation,an effective friction factor for oil-water flow is proposed.Employing the proposed correlations,the pressure gradient across the oil-water flow and hold-up volume fraction are predicted with significant reduction in error compared with that of conventionally employed correlations.The average error and standard deviation values of−7.06%,20.72%and 0.31%,18.79%are found for Stratified flow and dispersed flow respectively.

关键词： oil-water flow two-fluid model pressure gradient Stratified flow dispersed flow

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THE SOLITARY WAVES IN stratified SHEAR flow

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Acta Mechanica Sinica 1989年第1期5卷 37-48页

作者： R. Grimshaw School of Mathematics University of New South WalesAustralia

In this paper,the basic equation of internal long waves in stratified shear flow is derived un- der Boussinesq assumption,the first order approximation solution is given for solitary waves with the effects of slowly v... 详细信息

关键词： solitary wave Stratified flow shear flow

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