of high-viscosity oil-water flow

302 Pages·2015·7.8 MB·English

by  Shi, Jing

CRANFIELD UNIVERSITY

JING SHI

A STUDY ON HIGH-VISCOSITY OIL-WATER TWO-PHASE FLOW IN
HORIZONTAL PIPES

SCHOOL OF ENERGY, ENVIRONMENT AND AGRIFOOD
Oil and Gas Engineering Centre

PhD

Academic Year: 2012 – 2015

Supervisor: Professor Hoi Yeung
September 2015

CRANFIELD UNIVERSITY

SCHOOL OF ENERGY, ENVIRONMENT AND AGRIFOOD
Oil and Gas Engineering Centre

PhD

Academic Year 2012- 2015

JING SHI

A STUDY ON HIGH-VISCOSITY OIL-WATER TWO-PHASE FLOW IN
HORIZONTAL PIPES

Supervisor: Professor Hoi Yeung
September 2015

This thesis is submitted in partial fulfilment of the requirements for the
degree of Doctor of Philosophy

© Cranfield University 2015. All rights reserved. No part of this
publication may be reproduced without the written permission of the
copyright owner.

ABTRACT
A study on high-viscosity oil-water flow in horizontal pipes has been conducted
applying experimental, mechanism analysis and empirical modelling, and CFD
simulation approaches.
A horizontal 1 inch flow loop was modified by adding a designed sampling
section to achieve water holdup measurement. Experiments on high-viscosity
oil-water flow were conducted. Apart from the data obtained in the present
experiments, raw data from previous experiments conducted in the same
research group was collated. From the experimental investigation, it is found
that that the relationship between the water holdup of water-lubricated flow and
input water volume fraction is closely related to the oil core concentricity and oil
fouling on the pipe wall. The water holdup is higher than the input water volume
fraction only when the oil core is about concentric. The pressure gradient of
water-lubricated flow can be one to two orders of magnitude higher than that of
single water flow. This increased frictional loss is closely related to oil fouling on
the pipe wall.
Mechanism analysis and empirical modelling of oil-water flow were conducted.
The ratio of the gravitational force to viscous force was proposed to
characterise liquid-liquid flows in horizontal pipes into gravitational force
dominant, viscous force dominant and gravitational force and viscous force
comparable flow featured with different basic flow regimes. For viscous force
dominant flow, an empirical criterion on the formation of stable water-lubricated
flow was proposed. Existing empirical and mechanistic models for the prediction
of water holdup and/or pressure gradient were evaluated with the experimental
data; the applicability of different models is demonstrated.
Three-dimensional CFD modelling of oil-water flow was performed using the
commercial CFD code Fluent. The phase configurations calculated from the
CFD model show a fair agreement with those from experiments and mechanism
analysis. The velocity distribution of core annular flow is characterised with
nearly constant velocity across the oil core when the oil viscosity is significantly
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higher than the water viscosity, indicating that the high-viscosity oil core flows
inside the water as a solid body. The velocity profile becomes similar to that of
single phase flow as the oil viscosity becomes close to the water viscosity.
Key words:
Oil-water; high-viscosity oil; water holdup; oil fouling; pressure gradient; CFD

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ACKNOWLEDGEMENTS
It is pleasant to express my sincere gratitude to all those who have contributed
to the completion of the presented work. I am sincerely grateful to the following:
To Professor Hoi Yeung, my supervisor, for initiating the study and providing
support and stimulating discussions throughout the duration of this work;
without him, my study could not have been started and finished to a success.
To Dr Liyun Lao, for his advice on the design of the sampling section, training
on the operation of a three-phase rig and useful comments on my manuscript of
the experimental part.
To Stan Collins, our lab. manager, who offered valuable discussions and
technical support on pressure measurement and data acquisition; to the lab
technician Sheridan Cross who helped set up the experimental rig.
To Dr Mustapha Gourma, who was always ready to discuss with me on the
CFD simulation and gave me useful comments on the CFD part of the
manuscript; to Dr Yabin Zhao, who offered kind guide at the initial stage of my
CFD simulation study; to Andy Gittings, the university research computing
manager, who provided great support on high performance computing.
To Dr Hameed Al-Awadi, Dr Ezeddine Zorgani and Dr Solomon Alagbe, for
providing raw experimental data to make the present large experimental data
base; to my colleague Yahaya Baba who offered kind assist in my experiments;
to Sasha Quills and Sam Skears for their administrative support.
To Dr Shiwei Fan who has been there to offer numerous discussions.
And to my family, my parents, brother, sister-in-law, and little niece for their love
and support.

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TABLE OF CONTENTS
ABTRACT............................................................................................................ i
ACKNOWLEDGEMENTS................................................................................... iii
TABLE OF CONTENTS ..................................................................................... v
LIST OF FIGURES ........................................................................................... viii
LIST OF TABLES .............................................................................................. xv
LIST OF ABBREVIATIONS .............................................................................. xvi
LIST OF SYMBOLS ....................................................................................... xviii
1 INTRODUCTION ............................................................................................. 1
1.1 Background ............................................................................................... 1
1.1.1 Overview ............................................................................................ 1
1.1.2 Previous studies on high-viscosity oil-water flow at Cranfield
University .................................................................................................... 2
1.2 Objectives ................................................................................................. 3
1.3 Thesis outline ............................................................................................ 3
2 LITERATURE REVIEW ................................................................................... 5
2.1 Industrial background ................................................................................ 6
2.1.1 An overview on heavy oil production and transportation .................... 6
2.1.2 Industrial applications of water-lubricated heavy oil transport .......... 10
2.2 Experimental studies on high-viscosity oil-water flow ............................. 13
2.2.1 Basic flow notations in oil-water flow ................................................ 13
2.2.2 Previous experimental studies on high-viscosity oil-water pipeline
flow ............................................................................................................ 16
2.2.3 Summary .......................................................................................... 28
2.3 Modelling of multiphase flow in computational fluid dynamics ................ 32
2.3.1 Fundamentals of computational fluid dynamics ................................ 32
2.3.2 Multiphase computational fluid dynamics ......................................... 34
2.3.3 Numerical solution of transport equations ........................................ 37
3 EXPERIMENTAL SETUP AND PROGRAMME ............................................ 41
3.1 Introduction ............................................................................................. 41
3.2 Literature review on phase holdup measurement ................................... 41
3.3 Experimental setup ................................................................................. 43
3.4 Experimental procedure and runs ........................................................... 50
3.4.1 Experimental procedure ................................................................... 50
3.4.2 Experimental runs ............................................................................ 52
3.5 Assurance of experimental system ......................................................... 54
3.5.1 Pressure signals ............................................................................... 54
3.5.2 Oil viscosity ...................................................................................... 56
3.5.3 Accuracy of the sampling measurement .......................................... 58
3.5.4 Repeatability of the experiments ...................................................... 60
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3.6 Summary ................................................................................................ 61
4 EXPERIMENTAL RESULTS ......................................................................... 63
4.1 Introduction ............................................................................................. 63
4.2 Experimental data bank .......................................................................... 63
4.3 Flow patterns .......................................................................................... 65
4.3.1 Flow patterns observed in experiments ............................................ 65
4.3.2 Flow pattern maps ............................................................................ 73
4.4 Inversion occurrence ............................................................................... 86
4.5 Water holdup of water-lubricated flow ..................................................... 91
4.6 Pressure gradient of water-lubricated flow .............................................. 96
4.7 Summary .............................................................................................. 104
5 MECHANISM ANALYSIS AND EMPIRICAL MODELLING ......................... 107
5.1 Introduction ........................................................................................... 107
5.2 Flow patterns of liquid-liquid flow .......................................................... 107
5.2.1 Literature review on flow patterns of liquid-liquid flows in
horizontal pipes ....................................................................................... 107
5.2.2 Gravitation to viscous force ratio to characterise liquid-liquid flow
systems ................................................................................................... 115
5.3 Inversion occurrence ............................................................................. 129
5.4 Water holdup and pressure gradient of water-lubricated flow ............... 132
5.4.1 Review on models of water-lubricated flow .................................... 133
5.4.2 Model development for water-lubricated flow ................................. 140
5.4.3 Evaluation of models ...................................................................... 149
5.5 Summary .............................................................................................. 163
6 CFD SIMULATION SETUP AND PROGRAMME ........................................ 167
6.1 Introduction ........................................................................................... 167
6.2 Mathematical models ............................................................................ 168
6.2.1 VOF model ..................................................................................... 168
6.2.2 SST k-ω turbulence model ............................................................. 170
6.3 Physical models .................................................................................... 171
6.4 Simulation setup ................................................................................... 173
6.4.1 Boundary conditions ....................................................................... 173
6.4.2 Solution setup ................................................................................ 174
6.5 Simulation runs ..................................................................................... 175
6.6 Preliminary simulation results ............................................................... 180
6.6.1 Influence of mesh sizes .................................................................. 180
6.6.2 Influence of initialization methods .................................................. 181
6.6.3 Influence of volume fraction interpolation schemes at phase
interface .................................................................................................. 185
6.6.4 Influence of turbulence schemes .................................................... 186
6.6.5 Influence of wall contact angles ..................................................... 189
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