SDAG
Discretization Methods for Multiphase Flow Simulation of Ultra-Long Gas-Condensate Pipelines Erich Zakarian & Henning Holm Shtokman Development A.G.
www.bhrgroup.co.uk 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
SDAG
Contents • The Shtokman field development • Profile discretization of gas-condensate pipelines • Objective and requirements • Method 1 – concept of pipeline profile indicator • Method 2 – concept of lumping and redistribution • Comparison and simulation
• Conclusions
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
SDAG Integrated Development of the Shtokman Gas-Condensate Field – Phase 1
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Gas export to shore
• 70 MSm3/d (2.5 BCFD) – Phase 1 • 2 x 36” ND trunklines (0.86 m ID) • Length 558 km (347 miles)
Shtokman Teriberka
• Dry two-phase flow • CGR = from 2 to 16 Sm3/MSm3
Murmansk
Paris
Cannes 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
SDAG
Shtokman pipeline profile 200
Elevation [m]
100 0 -100 -200 -300 -400 0
100
200
300
400
500
Distance [km]
•
Detailed pipeline profile from seabed bathymetry survey (2007)
•
Free span analysis and seabed intervention taken into account
108,785 points 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
SDAG
Pipeline profile discretization: objective Given either as-built profile or detailed terrain survey • In transient multiphase flow simulation, the actual or expected pipeline geometry must be simplified to achieve reasonable CPU time • For long pipelines (> 100 km) laid on rough terrain, compression of a large set of data points is required typically from 104-105 points to few 103 points Target Î Simulation time ≥ 24 x CPU time 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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The Shtokman case Target ≈ 2500 pipes for a total length of 554 km
• Average pipe length will be approximately 200 m • Avoid small pipe sections to maximize numerical time steps Δt < min (Δx/U)i
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Pipeline profile discretization: requirements 1. The total pipe length must be conserved 2. The simplified geometry must have the same overall shape (large and small scale undulations) 3. The pipe angle distribution of the discretized profile must be as close as possible to the original distribution 4. The total climb (cumulative length of uphill pipes) must be conserved to predict the same overall liquid content in steady-state flow conditions 1
3 2
Original profile 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
4
SDAG
Liquid holdup vs. pipe inclination 0.70
Liquid holdup [-]
0.60
USG = 1.00 m/s USG = 1.50 m/s
0.50
USG = 2.00 m/s
0.40
USG = 2.50 m/s USG = 3.00 m/s
0.30
USG = 3.50 m/s USG = 4.00 m/s
0.20
USG = 4.50 m/s
0.10 0.00 -5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
8
9
Pipe inclination [deg] 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
10
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Two methods for a single objective Method 1: concept of pipeline profile indicator • Select, simplify and complexify relevant sub-profiles • Use the pipeline profile indicator and the total climb to match the original angle distribution Method 2: concept of lumping elements with similar inclination • Redistribution to match the original large & small scale topographies
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Method 1 Concept of pipeline profile indicator
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Definition: pipeline profile indicator ∑ [Holdup(θ i ) − Holdup(0)]× Li N
PI =
i =1
N
× 1000
∑ Li i =1
Holdup (θ i ) =
0.49
π
Arc tan[1.9 × (θ i − 0.66 )] + 0.25
θi = inclination of pipe i with respect to horizontal [%] Li = length of pipe i [m] N = number of pipes B. Barrau, “Profile indicator helps predict pipeline holdup, slugging”, Oil & Gas Journal Vol. 98, Issue 8, p. 58-62, Feb 21, 2000 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Holdup function vs. OLGAS 0.70
Liquid holdup [-]
0.60
Holdup function USG = 1.00 m/s
0.50
USG = 1.50 m/s USG = 2.00 m/s
0.40
USG = 2.50 m/s USG = 3.00 m/s
0.30
USG = 3.50 m/s USG = 4.00 m/s
0.20
USG = 4.50 m/s
0.10 0.00 -5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
8
Pipe inclination [deg] 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
9
10
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Pipeline profile indicator scale From Total E&P experience in gas-condensate pipeline design and operation Pipeline profile is globally sloping downwards No particular operating problem to be expected Pipeline profile is nearly horizontal or over-simplified 0 < PI < 20 No particular operating problem to be expected PI < 0
Pipeline profile is relatively flat or slightly hilly Possible troubles at very low flow rates or during restart Pipeline crosses hilly terrain 40 < PI < 80 Design & Operation needs particular attention Pipeline profile is very hilly or very steep Design & Operation needs very careful attention 80 < PI Validity of simulation software to be checked 20 < PI < 40
Shtokman pipeline profile indicator = 79.7 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Step 1: sub-profile selection
Pipe inclination
230000
Inclination [deg]
Inclination [deg]
Pipe inclination 10 8 6 4 2 0 -2 -4 -6 -8 -10
240000
250000
260000
270000
10 8 6 4 2 0 -2 -4 -6 -8 -10
280000
410000
Pipeline indicattor [-]
Distance from offshore platform [m]
420000
430000
440000
450000
Distance from offshore platform [m]
180 160 140 120 100 80 60 40 20 0
0
100000
200000
300000
400000
Distance from offshore platform [m]
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
500000
460000
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Step 2: simplification of the original profile • Final average pipe length should be about 200 m (target ≈ 2500 pipes) • For example, use the Box Filter from OLGA® Geometry Editor
• Or simply select one point every 1 km 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Step 2: result Pipeline geometry 5000 4500 4000 3500 3000 2500 2000 1500 1000 500 0
Pipe elevation (simplified profile) [m] Pipe elevation (original profile: 108,785 points) [m] Total climb (original profile: 108,785 points) [m] Total Climb (simplified profile) [m]
100 0 -100 -200 -300 -400
0
100000
200000
300000
400000
500000
Distance from offshore platform [m]
Inclination [deg]
Pipe inclination (original profile: 108,785 points) [deg] Pipe inclination (simplified profile) [deg]
0
100000
200000
300000
PI = 79.7 25.8
Pipe inclination 20 15 10 5 0 -5 -10 -15
Total climb [m]
Elevation [m]
200
400000
Distance from offshore platform [m]
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
500000
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Step 3: complexification •
Split the simplified profile into smaller pipes 5 smaller pipes per simplified pipe Î pipe length ≈ 200 m
•
Move new points up and down with a random process
-305
Complexified profile -310
Simplified profile
For each sub-profile
Elevation [m]
-315 -320
•
Keep original pipeline indicator within +/-1%
•
Keep original total climb within +/- 1%
-325 -330 -335 -340
0
2000
4000
6000
8000
10000
Distance from offshore platform [m]
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Step 3: result Pipeline geometry 200
5000 4500 4000 3500 3000 2500 2000 1500 1000 500 0
Pipe elevation (complexified profile) [m] Pipe elevation (original profile: 108,785 points) [m] Total climb (complexified profile) [m] Total climb (original profile: 108,785 points) [m]
100 0 -100 -200 -300 -400
0
100000
200000
300000
400000
500000
400000
500000
Distance from offshore platform [m]
Inclination [deg]
Pipe inclination 20 15 10 5 0 -5 -10 -15
Pipe inclination (original profile: 108,785 points) [deg] Pipe inclination (complexified profile) [deg]
0
100000
200000
300000
Distance from offshore platform [m]
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
Total climb [m]
Elevation [m]
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Method 2 Concept of lumping elements with similar inclination
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Method 2 – “Lumping and redistributing” 1.
Define the criteria (in priority) to determine the pipe length to be used for the simplified profile : 1.
minimum pipe length
2.
maximum elevation change for a pipe element
3.
maximum pipe length
2.
Sort all elements in the detailed profile by inclination in ascending order
3.
Lump together the sorted elements to longer pipes, starting with the element with the steepest downhill inclination. The length of each pipe element is then limited by dominating criteria in 1).
4.
Distribute the pipe elements in the simplified profile to match the large scale and small scale topography of the detailed profile. 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
SDAG Step 1) Define the criteria (in priority) to determine the pipe length to be used for the simplified profile : 1.
minimum pipe length (200 m)
2.
maximum elevation change for a pipe element (5 m)
3.
maximum pipe length (1000 m)
Maximum elevation change
1000
20
Elevation change of single pipe
900
15
Pipe length
800
10
700
5
600
0
500
-5
400
-10
300
-15
200
-20
100
-25 Xmin
Pipelength (m)
Xmax
0 -8
-6
-4
-2
0 Pipe inclination (deg)
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
2
4
6
8
P ip e le n g t h ( m )
E le v a t io n c h a n g e ( m )
Pipe elevation change (m)
25
SDAG Step 2) Sort elements in the detailed profile by inclination in ascending order – divide into 0subsections if required -400 -600 -800 -1000 -1200 0
100000
200000
300000
400000
500000
600000
-200 -300 -400 -500 -600
Original profile
-700 -800 -900 -1000 -1100 -1200
Inclination
Lumped, but not redistributed profile 0
50000 Distance (m)
5 4 3 2 1 0 -1 -2 -3 -4 -5 100000
Inclination (deg)
Distance (m)
Elevation (m)
Elevation (m)
-200
Step 3) Lump together the sorted elements to longer pipes, starting with the element with the steepest downhill inclination. The length of each pipe element is then limited by dominating criteria in 1).
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
SDAG ”Inclination classes” versus ”lumping by inclination in ascending order ”
600000
Original profile 20-70 km
Lumping by inclinations in ascending order
Condensate content [m3]
500000
Accumulated length (m)
2000
grouping by inclination classes
400000
300000
200000
1800
'lumping by inclination in ascending order'
1600
'Sorted by inclination classes'
1400 1200 1000 800 600 400
100000
200 0
0 -5
-4
-3
-2
-1
0
1
Inclination (deg)
2
3
4
5
30
35
40
45
50
55
60
Export flow rate [MSm3/d]
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
65
70
SDAG Step 4) Redistribution of elements by “Simulated Annealing” (Travelling salesman problem) “minimize distance between detailed profile and simplified profile” 0
Elevation (m)
-200
Cost function:
F ( y ) = ∑i wi ⋅ ( yi − yi ) 2 ŷi :
-600 -800 -1000 -1200 0
100000
200000
300000
400000
500000
600000
400000
500000
600000
90000
95000
Distance (m)
0
values from the simplified profile
-50 Elevation (m)
yi :
-400
values from the detailed profile
-100 -150 -200 -250 -300 -350 -400
weight factor
where as “i” denotes: 1)
Elevation
2)
“Total Climb”
3)
“Pipeline Indicator” *
0
100000
200000
300000 Distance (m)
Elevation (m)
wi :
-230 -240 -250 -260 -270 -280 -290 -300 70000
75000
80000
85000 Distance (m)
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
100000
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Comparison Original Simplified Method 1 profile profile profile Number of pipes 108,784 554 2,766 Pipeline profile indicator 79.7 25.8 80.3 Total climb [m] 4,187 1,235 4,180 Total length [m] 554,505 554,400 554,507
Method 2 profile 2,550 80.3 4,187 554,505
Elevation [m]
Pipeline geometry -230 -240 -250 -260 -270 -280 -290 -300
70000
75000
80000
85000
90000
Distance from offshore platform [m] 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
Original profile Simplified 95000 profile 100000 Discretized profile (method 1) Discretized profile (method 2)
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Angle distributions 80000 Original profile Discretized profile (Method 2) Discretized profile (Method 1) Simplified profile
70000 60000 50000 40000 30000 20000 10000
0, -6 (-3 0) 0, -2 0 (-1 ) 0, -5 ) (-2 ,(-0 1) .5 ,0. 25 ) (0 ,0 .0 1) (0 .1 ,0 .2 ) (0 .3 ,0 .4 (0 ) .5 ,0 .7 5) (1 ,1 .2 5) (1 .5 ,2 ) (2 .5 ,3 ) (4 ,5 ) (6 ,7 ) (8 ,9 ) (1 0, 20 ) (3 0, 90 )
0
(-9
Total pipe length per angle group [m]
Pipe angle distribution
Pipe angle group [deg] 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Steady-state simulation: original vs. discretization Condensate content vs. export flow rate 42" ND pipeline - Fluid: 50%J0/50%J1 - OLGA steady-state pre-processor 2000 Original profile 20-70 km
Condensate content [m3]
1800
Discretized profile 20-70 km (Method 1)
1600
Discretized profile 20-70 km (Method 2)
1400 1200 1000 800 600 400 200 0 30
35
40
45
50
55
60
Export flow rate [MSm3/d] 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
65
70
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Steady-state simulation: simplified vs. discretization Total condensate content vs. export flow rate 42" ND pipeline - Fluid: 50%J0/50%J1 - OLGA steady-state pre-processor 200
Total condensate content (simplified profile) Total condensate content (method 1) Total condensate content (method 2) Inlet pressure (simplified profile) Inlet pressure (method 1) Inlet pressure (method 2)
9000 8000 7000
180 160
6000 140
5000 4000
120
3000 2000
100
1000 0
80 20
25
30
35
40
45
50
55
60
Export flow rate [MSm3/d] 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
65
70
Inlet pressure [bara]
Total condensate content [m3]
10000
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Conclusions • Simplification of long and rough gas-condensate pipeline profiles is a key issue for correct design • Two methods were introduced for the development of the Shtokman field – Phase 1 • Essential characteristics of the original detailed pipeline profile are conserved: Length + Topography + Angle distribution + Total climb
• The hydrodynamic behavior of the original profile is conserved through both methods despite significant data compression 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Discretization Methods for Multiphase Flow Simulation of Ultra-Long GasCondensate Pipelines Erich Zakarian, Henning Holm Shtokman Development A.G., Russia
[email protected],
[email protected]
Dominique Larrey Total E&P, Process Department, France
[email protected] 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Back-up
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Why discretization is so important? Total condensate content vs. export flow rate 42" ND pipeline - Fluid: 50%J0/50%J1 - OLGA steady-state pre-processor
Total condensate content [m3]
10000 Simplified profile
9000
Discretized profile (Method 1)
8000
Discretized profile (Method 2)
7000 6000 5000 4000 3000 2000 1000 0 20
30
40
50
Export flow rate [MSm3/d]
60
70
Poor discretization Î Incorrect design of receiving facilities Î Wrong operating envelope Î Reduced operating flexibility Î Higher risk of continuous flaring Î Wrong model tuning against field data
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Seabed profile 200
Elevation [m]
100 0 -100 -200
3D Side Scan Sonar imagery
-300 -400 0
100
200
300
400
500
Distance [km]
Ice scours & depressions
Elongated pockmarks
Ridges & ice scours
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
Pockmarks
SDAG
Total climb • Total climb = cumulative length of uphill pipes • Helpful indicator as a first check • Relevant indicator in addition to the pipeline profile indicator to match the original angle distribution Shtokman original pipeline profile (2007 survey) Total climb = 4187 m
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Comparison of the discretization methods Pipeline geometry
5000
Pipe elevation (discretized profile: first method) [m] Pipe elevation (discretized profile: second method)[m] Total climb (discretized profile: first method) [m] Total climb (discretized profile: second method) [m]
100 0 -100
4000 3000 2000
-200 -300
1000
-400
0
0
100000
200000
300000
400000
500000
400000
500000
Inclination [deg]
Distance from offshore platform [m] Pipe inclination (discretized profile: first method) [m] Pipe inclination (discretized profile: second method) [m]
10 8 6 4 2 0 -2 -4 -6 -8 -10
0
100000
200000
Pipe inclination
300000
Distance from offshore platform [m]
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
Total climb [m]
Elevation [m]
200
SDAG
OLGA® Geometry Editor Box filter
Angle distribution preservation
• Ok for removing noise from as-built pipeline survey • Not recommended for hilly pipelines
• Requires pre-definition of angle groups • Several tries are necessary • Extremely difficult or even impossible to satisfy the four criteria
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Next? • Improve the simplification step (method 1) to keep as many original high & low points as possible • Sensitivity analysis to pipe sectioning (meshing) in dynamic simulation • Seabed topography characterization with pipeline profile indicator Î Build realistic profile when no detailed survey is available
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Hydraulic/level gradients at low flow rate Keep as many original high & low points as possible to match hydraulic gradients
• Level gradients included in OLGA 6 (steady-state pre-processor) • Implicitly included in dynamic mode but fine mesh is required 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
SDAG
Pipeline route 200
Elevation [m]
100 0 -100 -200 -300 -400 0
100
200
300
400
Distance [km]
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
500
SDAG
The devil is in the details… ‐265 ‐270 ‐275 ‐280 ‐285
Elevation [m]
50
51
52
53
54
55
56
57
58
59
60
‐220 ‐240 ‐260 ‐280 ‐300 ‐320 ‐340 ‐360 0
10
20
30
40
50
60
70
Distance from offshore platform [km] 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
80
90
100
SDAG Sh ore ll nd fa La
Po ck ma rks
Be nig n
El po onga ck ma ted rks Ic & e sc po ck ours ma rks Be ni Po gn ck ma rks R & Ice idge sc s ou rs
Be nig n
Po c Be kma nig rk n s Elo po ng ck ate ma d rks
Be ni gn
& Ice s de pr cou es rs sio ns
Pipe elevation & total climb vs. seabed topology
Pipe elevation (original profile: 108,785 points) [m] Total climb (original profile: 108,785 points) [m]
Elevation [m]
3D Side Scan Sonar imagery
100 0 -100 -200 -300 -400
0
Ice scours & depressions
100000
200000 300000 Distance from offshore platform [m]
Elongated pockmarks
400000
Ridges & ice scours
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
Total climb [m]
4500 4000 3500 3000 2500 2000 1500 1000 500 0
200
500000
Pockmarks
SDAG
Pipeline indicattor [-]
3D Side Scan Sonar imagery
Sh ore ll nd fa La
Po ck ma rks
Be nig n
El po onga ck ma ted rks Ice & po sco ck urs ma rks Be ni Po gn ck ma rks R & Ice idge sc s ou rs
Be nig n
Po ck Be mar nig ks n Elo po ng ck ate ma d rks
& Ice s de pr cou es rs sio ns
Be ni gn
Pipeline profile indicator vs. seabed topology
180 160 140 120 100 80 60 40 20 0
0
100000
200000
300000
400000
500000
Distance from offshore platform [m]
Ice scours & depressions
Elongated pockmarks
Ridges & ice scours
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
Pockmarks
SDAG
Method 1: sub-profile indicator and total climb Length range [km]
0-10
10-20
20-70
70-140
140-180
180-200
Pipeline indicator [-] Total climb [m]
58.48 55.04
89.24 75.12
104.83 483.90
82.48 612.43
61.97 199.31
80.77 131.14
200-220
220-230
230-280
280-320
320-360
360-410
97.95 189.26
63.40 58.97
45.57 171.22
77.01 273.30
100.03 386.93
67.64 254.57
410-460
460-500
500-510
510-540
540-554
Pipeline indicator [-]
106.54
38.09
64.23
85.74
151.63
Total climb [m]
599.81
144.93
49.85
195.13
306.09
Length range [km] Pipeline indicator [-] Total climb [m] Length range [km]
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Method 1: profile complexification y inew = y iold + C x × NormStd −1 (Rnd ) 4
Inverse of the standard normal cumulative distribution
3
NormStd‐1
2
Cx = complexification coefficient
1
Rnd = random value between 0 and 1
0
NormStd (x ) =
‐1 ‐2
x
∫
−∞
‐3 ‐4 0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Probability
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
1 2π
−z2 e 2
dz
SDAG
Steady-state simulation: original vs. discretization Inlet pressure vs. export flow rate 42" ND pipeline - Fluid: 50%J0/50%J1 - OLGA steady-state pre-processor 190
Inlet pressure at KP 20 [bara]
Original profile 20-70 km 180
Discretized profile 20-70 km (Method 1) Discretized profile 20-70 km (Method 2)
170
Back-pressure - Kilometer Point 70
160 150 140 130 120 110 10
20
30
40
50
60
Export flow rate [MSm3/d] 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
70
SDAG
Steady-state simulation: original vs. discretization Condensate content vs. export flow rate 42" ND pipeline - Fluid: 50%J0/50%J1 - OLGA steady-state pre-processor 12000
Condensate content [m3]
Original profile 20-70 km Discretized profile 20-70 km (Method 1)
10000
Discretized profile 20-70 km (Method 2) 8000 6000 4000 2000 0 10
20
30
40
50
Export flow rate [MSm3/d] 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
60
70
SDAG
Dynamic simulation Total condensate content vs. export flow rate 42" ND pipeline - Fluid: 50% J0/50% J1
10000
First discretization method - OLGA SS pre-processor Second discretization method - OLGA SS pre-processor First discretization method - OLGA dynamic Second discretization method - OLGA dynamic
Total condensate content [m3]
9000 8000 7000 6000 5000 4000 3000 2000 1000 0 30
35
40
45
50
55
60
Export flow rate [MSm3/d] 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
65
70
SDAG
CPU time Required simulation time to reach steady‐state flow conditions
Required computation time to reach steady‐state flow conditions First discretization method Second discretization method
30 days
33 h
Simulation time 20 days
21 h
7 days
28
35
49
Export flow rate [MSm3/d]
20 h 21 h 10 h 10 h 5 h 6 h
5 days
70
28
35
49
70
Export flow rate [MSm3/d]
DELL OptiPlex 755 - Intel® Core TM 2 Duo Processor E6750 (2.66 GHz) and 3.25 GB of DDR2 RAM. 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
SDAG
Dynamic simulation Total condensate content and inlet pressure vs. time 1,054
140.1
1,052
140.0
1,050
139.9
1,048
139.8
1,046
139.7
1,044
139.6
1,042
139.5
Total condensate content [m3]
1,040
139.4
Inlet pressure [bara]
1,038
139.3 0
1
2
3
4
5
6
7
8
9
Time [d]
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
10
Inlet pressure [bara]
Total condensate content [m3]
Winter conditions - Fluid 50%J0 / 50%J1 - Flowrate = 49MSm3/d
SDAG
Ramp-up from unpacked conditions
Transient 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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3D Side Scan Sonar imagery
Objective: to detect potentially dangerous objects and seabed features 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
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Shtokman pipeline route Characterization •
Iceberg scours 46% - typically 250m across x 8m deep
•
Pockmarks 20% - mostly ’elongated’ - 150m long x 5m deep
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Benign 34% - posing no problem for pipeline
Water depths •
Maximum 346m - mostly 200-250m
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Minimum 123m - except for final 3km shore approach
Seabed •
Generally soft clay 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
SDAG
Pockmarks •
Local craters/depressions of conical form
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Related to fluid expulsion from seabed, either liquid (water) or gas from natural or biogenic origin
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Apart from iceberg scours, the most prominent features found on the seabed
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Diameters from 5 to 120 m
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Depths from 0.5 m to 8 m
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Wall inclinations from 1.5° to 25°
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Densities from 16 to 350 per km²
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Can form chain-like features
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Approximately 13,500 along trunkline corridor 14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
SDAG
Elongated pockmarks •
Local elongated craters/depressions
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Lengths 60 – 400m,
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Widths 25 – 120m
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Depths 0.5 – 10m
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Wall inclinations in the main direction from 0.5° to 3.5°
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Opposite wall inclination from 2° to 7°
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
SDAG
Iceberg scours •
Crisscrossing scours
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Depths 0.8 – 16 m
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Widths 37 – 300 m
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Lengths 3.5 – 6 km
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V-shaped or U-shaped cross-sections
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Wall inclinations 2.5° – 37.5°
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
SDAG
Gas export system
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
SDAG
Pipe wall thickness – 2x36” trunkline (X65)
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009
SDAG
Pipe stability – 2x36” trunkline (X65)
14th International Conference Multiphase Production Technology Cannes, France - 17th - 19th June 2009