pipelines & flow assurance
TRANSCRIPT
Pipelines & Flow Assurance
Christophe Meynet
Senior CFD Consultant,
Wood Group Kenny
Using CFD To Predict Pig BehaviourChristophe Meynet, Senior CFD Consultant, Aberdeen
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1. Introduction
2. CFD Modeling
3. Output and results
4. Conclusions & Way Forward
Agenda
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• Pigging is necessary for various reasons:
• Cleaning
• Inspection
• Pre-commissioning
• Pigs can be made of different materials
• The main risk with pigging is the pig getting stuck
1. Introduction – About pigging
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1. Introduction – Tie in location
10”
24”
34”
NEW FIELD• Added problem – 10” pig passing
through 24” then 34” pipeline
• CFD can be used to assist pig
manufacturer during design to
confirm passage of pig
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1. Introduction – Design requirements – Weak link
24”
10”
24” PIG
HOT TAP CONNECTION
“LIP SHAPED” INTERSECTION
ABILITY TO SNAP IN TWO
RISK FOR THE PIG TO GET STUCK
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1. Introduction – Design requirements – Density
“DEAD LEG”
PIG LIGHTER
THAN FLUID
PIG NEEDS TO BE HEAVIER THAN
CARRYING FLUID
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1. Introduction – Design requirements – Onset velocity
MINIMUM FLOW RATE TO DISPLACE PIG?
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1. Introduction – Design requirements – Wye pieces
?
“DEAD LEG”
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1. Introduction – Design requirements – Wye pieces
?
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2. CFD models – Individual pigs
VELOCITY INLET
OUTLET
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2. CFD models – Wye
CAD MODEL PROVIDED
CFD MODEL
VELOCITY INLET
OUTLET
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3. Results – Individual pigsF
IXE
D V
EL
OC
ITY
IN
LE
T
VELOCITY MAGNITUDE
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3. Results – Individual pigs
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0
10
20
30
40
50
60
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1L
IFT
FO
RC
E [
N]
DR
AG
FO
RC
E [
N]
INLET VELOCITY [m/s]
DRAG
LIFT
FLIFT
FDRAG
FIX
ED
VE
LO
CIT
Y I
NL
ET
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3. Results – Friction Theory
AXIAL FORCE
NORMAL FORCE
𝑓𝑠𝑡𝑎𝑡𝑖𝑐 = 𝛼𝑓𝑛𝑜𝑟𝑚𝑎𝑙 𝑓𝑘𝑖𝑛𝑒𝑡𝑖𝑐 = 𝛽𝑓𝑛𝑜𝑟𝑚𝑎𝑙
𝛼 >> 𝛽
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3. Results – Frictions Theory
𝑓𝑛𝑜𝑟𝑚𝑎𝑙 = 𝑚𝑔 − 𝜌𝑓𝑙𝑢𝑖𝑑𝑉𝑑𝑖𝑠𝑝𝑙𝑎𝑐𝑒𝑑
G
𝑚𝑔
𝜌𝑓𝑙𝑢𝑖𝑑𝑉𝑑𝑖𝑠𝑝𝑙𝑎𝑐𝑒𝑑
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3. Results – Onset velocity
𝑓𝑠𝑡𝑎𝑡𝑖𝑐 𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛𝑠
PREDICTED ONSET VELOCITY
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3. Results – Onset velocity
𝑓𝑠𝑡𝑎𝑡𝑖𝑐 𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛𝑠
MEASURED ONSET VELOCITY
𝑓𝑠𝑡𝑎𝑡𝑖𝑐
𝛼“Static
friction factor”
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3. Results – Wye
LOCAL COORDINATES
ATTACHED TO PIG COG
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3. Results – Wye
-4
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
-0.05
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
0.05
0 0.2 0.4 0.6 0.8 1 1.2 1.4F
OR
CE
[N
]
MO
ME
NT
[N
.m]
OFFSET [m]
M_x_local [N.m] M_y_local [N.m]
F_x_local [N] F_z_local [N]
VELOCITY MAG.
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4. Conclusions & Way forward
• CFD was successfully used to improve knowledge on how the pig behaved when going through various piping elements
• Such study can be done in a cost efficient manner and identify potential “stuck pig” risks during pigging operations
• Testing rigs and procedures should be adapted to improve the accuracy of friction factors estimates which will improve onset velocity predictions
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Thanks for listening… Any question ?