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

SDAG

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

SDAG

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

SDAG

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]

 

SDAG

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

SDAG

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)

SDAG

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

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 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

SDAG

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

SDAG

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

SDAG

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

SDAG

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

SDAG

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

SDAG

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

SDAG

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

SDAG

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

SDAG

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

SDAG

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

SDAG

Shtokman pipeline route Characterization •

Iceberg scours 46% - typically 250m across x 8m deep

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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