DNV GL © 2016
Ungraded
30 October 2016 SAFER, SMARTER, GREENER DNV GL © 2016
Ungraded
30 October 2016
Mazdak Parsi
OIL & GAS
Erosion and Corrosion for Oil & Gas Equipment
1
(Application of CFD)
DNV GL © 2016
Ungraded
30 October 2016
Outline
Erosion in Oil and Gas Equipment
Erosion Equation Development
Erosion in Choke valves
CFD-based Erosion Modeling for Multiphase Flow
RCA Multiphase Flow Modeling
Conclusions
2
DNV GL © 2016
Ungraded
30 October 2016
Erosion in Oil and Gas Equipment
“For the majority of oil & gas fields, sand
from the reservoir formation is an
inevitable by-product”.
Erosion: a complex mechanical process in
which material is removed from the
pipeline due to repeated sand particle
impacts.
“Sand may cause damage to well
components such as sand screens,
tubing, down-hole safety valves,
electrical submersed pumps (ESPs)”.
Consequences: pipe failures, financial
losses, environmental issues…
3
DNV GL © 2016
Ungraded
30 October 2016
Erosion Equation Development
6
Figure 3: CFD unstructured mesh with 770k elements and inflation layers around the specimen.
DNV GL © 2016
Ungraded
30 October 2016
Erosion Equation Development
7
(a) 30º (b) 45º (c) 60º (d) 75º
(e) 90º (f) flow streamlines for θ = 90º
Figure 6: Contours of velocity magnitude for different impact angles (Vg = 102 m/s).
Velocity Contours
DNV GL © 2016
Ungraded
30 October 2016
Erosion Equation Development
8
(a)
(b)
(c)
Figure 11: Erosion ratios for gas velocities of a) 54 m/s, b) 79 m/s, c) 102 m/s.
(a)
(b)
(c)
Figure 11: Erosion ratios for gas velocities of a) 54 m/s, b) 79 m/s, c) 102 m/s.
DNV GL © 2016
Ungraded
30 October 2016
Examples – Erosion in Choke Valves
Problem: Particle impact at the small
area with high velocity causing
excessive erosion
9
Flow Inlet
Particle trajectories colored by velocity and associated erosion
area for two chokes
Area of high erosion
DNV GL © 2016
Ungraded
30 October 2016
Examples – Erosion in Choke Valves (Cont’d)
Results
10
Brick stopper
Choke gallery Downstream piping
DNV GL © 2016
Ungraded
30 October 2016 12
Early Life Late Life
Gas condensate wells
liquid production increases
pressure decreases
gas flow rate decreases
Annular flow Slug flow Churn flow transition
Introduction and Background
DNV GL © 2016
Ungraded
30 October 2016
Wire-Mesh Sensor (Validation of CFD Results)
13
CFD simulations require experimental data for validation.
Wire-Mesh Sensor provides void fraction distribution over the pipe cross-
section.
Data Analysis: phase distributions, void fraction time series, periodic structure
velocities, etc.
DNV GL © 2016
Ungraded
30 October 2016
Phase Distributions (different liquid structures)
14
Void Fraction
Liquid
Gas
Slug Pseudo Slug Huge Wave
Violent Agitation
Gas Trough
DNV GL © 2016
Ungraded
30 October 2016
CFD Simulation of Multiphase Flow
15
gas liquid
Typical Mesh
Typical Inlet Conditions
DNV GL © 2016
Ungraded
30 October 2016
CFD vs WMS (Radial Void Fraction Profile)
17
VSG = 10.3 m/s VSL= 0.30 m/s
VSG = 18.1 m/s VSL= 0.30 m/s
VSG = 27.3 m/s VSL= 0.30 m/s
DNV GL © 2016
Ungraded
30 October 2016
CFD-based Erosion Modeling for Multiphase Flow
19
• Unsteady flow simulation and particle tracking are simultaneously
performed.
• The value of mass removal of wall per unit area was recorded during the simulation run-time. When the rate of mass removal reached a steady-state condition, the rate was used for erosion computation.
DNV GL © 2016
Ungraded
30 October 2016 20
VSG = 10.3 m/s VSL= 0.30 m/s
Steady-state
Particles start to impact
CFD-based Erosion Modeling for Multiphase Flow
DNV GL © 2016
Ungraded
30 October 2016 21
VSG = 27.3 m/s VSL= 0.30 m/s
CFD-based Erosion Modeling for Multiphase Flow
DNV GL © 2016
Ungraded
30 October 2016
Comparison of CFD Erosion Results to Experimental Data
22
VSG
(m/s)
VSL
(m/s)
Particle Size
(micron)
Erosion
Rate (mpy)
VSG
(m/s)
VSL
(m/s)
Particle Size
(micron)
Erosion
Rate (mpy)
1 9.8 0.58 300 587 10.3 0.3 300 1258
2 17.7 0.36 300 3154 18.1 0.3 300 3145
3 27.2 0.32 300 7421 27.3 0.3 300 7863
4 27.2 0.32 150 3681 27.3 0.3 150 3128
Case
No.
Experiment CFD
Experimental UT Data Acquisition
CFD vs Experiments (Parsi et al.; 2015)
Experiments: ultrasonic technique was
employed to measure erosion rates for a
variety of flow conditions.
DNV GL © 2016
Ungraded
30 October 2016
Erosion in Horizontal Multiphase Flow
23
Passage of a pseudo slug (flow direction from left to right)
DNV GL © 2016
Ungraded
30 October 2016
Void Fraction Time Series
24
X= 1m
X= 5m
X= 9m
Distance from inlet
DNV GL © 2016
Ungraded
30 October 2016
Erosion in Horizontal Multiphase Flow
26
Liquid film covering a large region of the elbow (flow direction from left to right).
DNV GL © 2016
Ungraded
30 October 2016 28
time-step air-water phase distributions particle concetration
t = 39.0 s
t = 40.0 s
t = 44.0 s
t = 46.0 s
t = 50.5 s
t = 52.0 s
Figure 10: Phase distribution and particle concentration contours at different time-step.
DNV GL © 2016
Ungraded
30 October 2016
RCA Multiphase Flow Modeling
31
Figure 1. Model of RC and computational grid.
DNV GL © 2016
Ungraded
30 October 2016
Iso-void Fraction & Phase Distributions
32
200 rpm 600 rpm 800 rpm 1200 rpm
DNV GL © 2016
Ungraded
30 October 2016
Wall-Shear Stress Time Series
35
200 rpm 600 rpm
800 rpm 1200 rpm
DNV GL © 2016
Ungraded
30 October 2016
Acknowledgement
37
• Dr. Mustafa Kara (DNV GL) • Dr. Jose Vera (DNV GL) • Mr. Madhu Agrawal (BP) • Dr. Anchal Jatale (ANSYS)