Design of Gas Transport Systems - NTNU

Design of Gas Transport Systems 

11 September 2013 

Elin Kristin Dale 

ekrd@statoil.com 

1 - 

TPG4140 – NATURGASS, NTNU

Design of gas transport systems 

• Part 1: 

− Intro Pipeline Transport Technology 

− Gas/condensate fields- and infrastructure development 

− System design of pipelines – terms and definitions 

• Part 2: 

− Design premises included examples 

− System design of multiphase pipelines 

− Pipeline pressure protection and leak detection 

2 - 

TPG4140 – NATURGASS 

NTNU

Part 1 

Intro Pipeline Transport technology 

3 - 



Pipeline Transport Technology 

“Development of total transport solutions - from Reservoir to Market” 

4 - 



Reservoir 

conditions 

Pipeline Transport Technology 

Market 

conditions 

‣ System definition 

‣ Hydraulic analysis 

‣ Optimisation of flow in pipeline network wrt 

capacity and gas quality management 

‣ Principles for pressure control and pressure 

protection 

‣ Interface management 

‣ Supervision, consultation and daily operation of 

leak detection system (PM-vakt) 

PLEM 

5 - 



The Norwegian Continental Shelf 

• Statoil has developed the world’s largest 

offshore gas pipeline network 

• Technical services are provided by Statoil for 

the world's most extensive submarine gas 

pipeline system: 

− 7800 km pipelines (30” – 44”) 

− Long term transport capacity approx. 

365 MSm 3 /d 

• Statoil is the leader in the construction of 

large-diameter pipelines in deep water. 

• On 1 st January 2002, Gassco became the 

operator for most of the gas pipeline systems 

from the Norwegian continental shelf. 

• On 1 st January 2003, Gassled became the 

owner for most of the gas pipeline systems 

(Statoil share 5%, Statoil+Petoro share 50,8 

%). 

6 - 



7 - 

Gas/condensate fields- and infrastructure 

development

Gas transport technology 

Volume 

50 

BCM 

20 

10 

5 

PIPELINE 

(North sea) 

CNG 

LNG 

(Barents sea) 

Floating LNG 

GTL/Methanol 

2 

1 

.50 

Electricity 

(HVDC) 

UNECONOMIC 

1000 2000 3000 4000 5000 

Distance to market - Km 

8 - 



Transport analysis 

New fields: 

• Volume profiles 

• Type gas 

• Profitability 

• Geography 

• Owners 

Transport 

Solutions 

Cost 

estimation 

Economical 

analyse 

Infrastructure 

• Spare capacity 

• Liquid recov. 

• Tariffs 

• Owners 

• Distance 

• Capacity 

• Tie-ins 

• Processing 

• Liquid recov.. 

• CO2 removal 

• CAPEX 

• OPEX 

• NPV 

• IRR 

• Profit index 

• Investment 

equivalent 7% 

after tax. 

Overall 

evaluation 

• SDA/SØA economy 

• Strategic fit 

• Stakeholders 

• Flexibility 

Market: 

• Supply situation 

• Geography 

• Pricing 

9 - 



Gas/condensate fields- and infrastructure 

development 

• Gas supply 

− Production profile 

− Build-up and plateau level 

• Market scenarios 

− Volume 

− Market opportunities (and flexibility) 

− Company based sales 

• Existing infrastructure 

− Platforms 

• Tie-ins and functional 

requirements 

− Pipelines 

• Capacity and ullage 

• New infrastructure requirements 

10 - 



Dry gas pipelines 

Reference: Flow of oil and gas in 

pipelines 

• What are needed to find pipeline capacity? 

− Pipeline length 

− Bulk temperature 

− Inlet pressure 

− Outlet pressure 

− Molar weight of the gas 

− Roughness of the pipeline 

− Diameter of the pipeline 

Q 

SC 

= 

2 

− p 

2 

) 

1 2 

T ( p 

137.2 

SC 

D 

P zMTL 

SC 

− Deposits in the pipeline 

2.666 

11 



Existing infrastructure - capacity 

• The pipeline between X and Y is 

the main link between the 

production at A and B and the 

terminal E. 

• Utilisation of the XY link affects the 

capacity towards E, creating a 

bottleneck and a gap between the 

actual delivery and the demand. 

• Routing of the gas will determine 

the possible transportation capacity 

at a given scenario. 

• The sum of exit capacity in a 

transport system is not necessarily 

equal the actual transport capacity. 

• Transport capacity is dependent on 

volume scenario, bottlenecks and 

dependencies. 

A B C 

D 

Tie-in new field – increased production 

from 10 to 30 MSm3/d 

14,7 20 20 10 

15 

X 

Producers 

19,7 

Production scenario 1 [MSm 3 /d] 

Exit terminals 

A B C D E 

Y 

Gap: ~15 

49,7 

E 

10 -> 30 40 10 15 65 

12 - 



Overall field architecture case – Johan Sverdrup 

• Example of business case: 

− New field discovery Johan Sverdrup, largest 

finding in the world in 2010/2011 

− 0,9-1,5 Bill barrels oil equivalents, 140 km 

offshore, 110 meter depth, 1900 meter below 

the seabed 

− Production horizon to 2050 

− Which field architecture will you recommend to 

your management ? 

• Some of the parameters to be evaluated : 

− Technical: Choice of installation (floater, fixed structure), store or transport, processing, 

naval architecture, sensitivity to weather/sea conditions (hurricane, waves, tide, 

temperature etc), fluid properties (wax, hydrates, corrosion etc.), pigging, ship transport 

path, design codes, infrastructure (helicopter base, logistics, storage equipment/fluids, 

accommodation) and pressure protection and leak detection. 

− Economic analyses: availability in marked, location of construction, rent or own, 

distance from field to market, pipeline transport fee, country laws and regulations, 

personnel availability, company philosophy. 

13 - 



Pipeline system design 

Terms and definitions 

14 

-

Pipeline system design – terms and definitions 

• Pipeline system 

• Pipeline 

− A pipeline with compressors or pump stations 

− Pressure reduction stations 

− Metering 

− Tankage 

− Supervisory control and data acquisition system (SCADA) 

− Safety systems 

− Corrosion protection systems 

Petroleum and natural gas industries 

Pipeline transportation systems, ISO 

13623 

− And other equipment, facility or building used in the transportation of fluids 

− Those facilities through which fluids are conveyed, including pipe, pig traps, 

components and appurtenances, up to and including the isolation valve. 

15 - 



Pipeline system design – system definition 

• The extent of the pipeline system, its functional requirements and applicable legislation 

should be defined and documented. 

• The extent of the system should be defined by describing the system, including the 

facilities with their general locations and demarcations and interfaces with other facilities. 

• The functional requirements should define the required design life and design conditions. 

Foreseeable normal, extreme and shut-in operating conditions with their possible ranges 

in flow rates, pressures, temperatures, fluid compositions and fluid qualities should be 

identified and considered when defining the design conditions. 

Petroleum and natural gas industries 

Pipeline transportation systems, ISO 13623 

OS F-101: Submarine Pipeline 

Systems 

16 - 



Pipeline systems 

Subsea Production Systems (ISO 13628) and 

Pipeline Transportation Systems (ISO 13623) 

ESV 

Platform/Floater 

PIG TRAP 

Subsea 

Production 

HIPPS 

SUBSEA 

PROCESSING 

UNIT 

Subsea isolation 

SSIV 

ESV 

PIG TRAP 

MANIFOLD 

X-MAS 

TREE 

PWV 

PMV 

CHOKE 

BRANCH 

RISER BASE 

SSIV 

CHECK 

SCSSV 

CHOKE 

MODULE 

TEMPLATE AND 

MANIFOLD 

LANDFALL 

ESV 

Onshore 

PIG TRAP 

Pipeline Systems: Subsea connection 

Single phase; Gas, Oil, condensate 

TEE 

CHECK + BLOCK 

Multiphase; 

PLEM 

17 - 



Pipeline Project Organisation (Typical) 

Project Manager 

Project Control 

Authority 

Procurement 

HSE 

Upstream 

Downstream 

Platform/Terminal 

Platform/Terminal 

Administration 

EIA 

Pipeline 

Engineering 

System/RFO 

Pipeline 

Construction 

Landfall 

Preparation for 

Operation 

18 - 



" I draw lines, I don't move trees" 

19 - 



Pipeline system design – work process 

Thermohydraulic 

analysis 

Functional 

requirements; 

gas routing, 

regularity, 

gas quality, 

agreements 

Overall 

Operational 

Philosophy; 

Control and 

Safety 

System, 

Environment, 

etc. 

System design 

concept 

Internal diameter, 

capacity, pressure 

and temperature 

profile, etc. 

Functional 

requirements, 

Regularity, 

Deliverability 

Control and Safety 

Philosophy 

Pipeline System 

Diagram, Process 

Flow Diagram 

P&ID’s 

QA 

Boundary conditions and technical interface between platform – pipeline – terminal 

20 - 



Part 2 

Design premises 

Hydraulic capacity and gas quality 

21 - 

Photo credit: Manfred Jarisch / StatoilHydro 



Pipeline system design – Hydraulic analysis 1/2 

• The objective of the system design 

− develop overall transport solutions for the gas chain from the field 

to the market which will maximize the value of the liquid- and gas 

products and without any unreasonable external conditions for 

any third party (fields or transport systems). 

− deliver gas quantities nominated by the buyers within the desired 

quality specifications. 

− ensure high availability and regularity within reasonable technical 

and economical limits and relevant agreements. 

22 - 



Pipeline system design – Hydraulic analysis 2/2 

• The hydraulics of the pipeline system should be analysed to demonstrate that the 

system can safely transport the fluids for the design conditions specified by the 

system definition, and to identify and determine the constraints and requirements for 

its operation. This analysis should cover steady-state and transient operating 

conditions. 

• Describe the function loads for the pipeline design 

− Pressure profile 

− Temperature profile 

− Density profile (fluid) 

− Velocity profile 

• Design cases: 

− Normal operation, start-up, planned shut-down, etc. 

− Not planned operation, emergency shut-down, depressurisation, etc. 

− Emergency preparedness analysis; accidents, pipe rupture, leakage etc. 

23 - 



Pipeline system design – Design premises 1/3 

• Pipeline Route 

− Length 

− Bathymetric profile 

• Environmental Conditions 

− Air temperature 

− Sea bottom temperature 

− Ground temperature 

− Geo-technical data (soil conditions) 

Temperature, °C 

Area B - Åsgard Transport, Kårstø temp. 

High Rough Likely Rough Low Rough 

5 

3 

1 

-1 

-3 

66 68 70 72 74 76 78 80 82 84 86 

Hydraulic capacity, MSm³/d 

Area B - Åsgard Transport, Kårstø pressure 

High Rough Likely Rough Low Rough 

Pressure, barg 

130 

125 

120 

115 

110 

105 

100 

95 

90 

85 

80 

66 68 70 72 74 76 78 80 82 84 86 

Hydraulic capacity, MSm³/d 

24 - 



Hydraulic capacity – Sensitivity analysis 

Variation of parameters and hydraulic capacity compared to basis 

Zeebrugge 69.5 MSm³/d (october) 

5 

Trenching -200 Km 

Length +/-10 Km 

4 

3 

Temperature 

10 micron 

2 

Roughness 1- 3 micron 

1 

Gas Composition 

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 

25 - 




• Pipeline Data 

− Design pressure 

− Design temperature 

− Internal diameter 

− Wall thickness 

− Internal coating 

− Concrete coating 

− Insulation 

− Trenching/dredging 

− Gravel/rock dumping 

26 - 



Langeled Bredero Shaw i Farsund Sept. 2004 

Concrete coating 

(330 000 m 3 ) 

= 1,5 Troll A GBS 

Total pipeline steel 

(962 000 t) 

= 40 Troll A deck 

Coating 

(25 000 t) 

= 3 Eiffel Towers 

Total coating “wire”: 

(51 900km) 

= 1.3 times 

around the equator 

1200 km a 12m pipes: 

Per pipe: 

Ca 25 tonns 

27 - 



The largest laying vessels 

Solitaire: 

The worlds largest pipeline laying 

vessel at Nyhamna 

Acergy Piper: 

At Sleipner T at start-up of the laying 

process 

28 - 




• Gas properties 

− Equation of state 

• Gas composition 

• Friction equation 

− Internal roughness 

• Transport specification 

• Sales gas specifications 

• Pressure Control System 

− Pressure regulating 

− Pressure safety 

• Pig trap arrangement 

− Pigging philosophy 

• Pipeline valve philosophy 

• Future requirements 

29 - 



Transport of 42” subsea pipeline 

valve 

• Double expanding gate 

• Weight of valve: 80 tons (60 cars..) 

• 10m high including activator: 

• Total of 100 tons 

30 - 



Why gas quality specifications? 

• Ensure interoperability /interchangeability (WI) 

• Ensure unproblematic transport of gas 

− Max/min temperature and pressure 

• Prevent corrosion and erosion of equipment 

− Water, CO 2 , H 2 S content 

• Prevent condensation of liquid (HC dew point) 

• Prevent gas hydrates (Water dew point) 

Hydrocarbon dew-point (-3 C, 69 barg) 

Water dew-point (-12 C, 69 barg) 

CO2 content (max 2.5 % mol) 

H2S content (5 mg/Nm3) 

GCV (Gross calorific value) 

Wobbe index (WI) 

Max/min pressure and temperature 

31 - 



Hydrates – main reason for temperature 

control in multiphase pipelines 

32 - 



33 

- 

System design of multiphase pipelines

The diameter dilemma of long gas-condensate 

pipelines 

Pressure drop (bara) 

50 

40 

30 

20 

Technical feasibility – for how long can reservoir drive production to shore? 

• Minimize pressure drop ⇒ large pipe diameter 

Operational acceptability – will system availability be high enough? 

• Minimize liquid inventory in pipeline ⇒ small pipe diameter 

Large 

ID 

Small 

ID 

Design 

rate 

20 22 24 26 28 30 32 34 

Gas rate (MSm 3/ d) 

Liquid content (m 3 ) 

8000 

7000 

6000 

5000 

4000 

3000 

2000 

1000 

0 

Large 

ID 

Small 

ID 


rate 

24 26 28 30 32 34 

Gas rate (MSm 3 /d) 

34 - 



Conventional design of gas-condensate pipelines 


50 

40 

30 

20 

Pipeline diameter: small 

• Minimize liquid inventory 

‣ Accept moderate/high pressure drop 

Slug-catcher size set by: 

• Rate increase: 

‣From maximum turndown to design 

rate 

• Pigging 

‣ Liquid inventory prior to pigging 

Maximum 

turndown 

Design pressure 

drop 


rate 

20 22 24 26 28 30 32 34 


Liquid content (m 3 ) 

8000 

7000 

6000 

5000 

4000 

3000 

2000 

1000 

Slug-catcher 

0 

volume 

Troll slug-catcher 

Maximum 

turndown 

Steady state 

liquid content 


rate 

24 26 28 30 32 34 

Gas rate (MSm 3 /d) 

35 - 



New design of gas-condensate pipelines 

Pipeline diameter: large 

• Minimize pressure drop 

‣ Accept relatively large liquid inventory 

• If possible, alleviate liquid load 

‣ Multi-diameter pipelines/dual lines 

• Exploit pipeline’s slow response to transients 

‣ Operational procedures 


50 

40 

30 

20 

Large 

ID 

Small 

ID 

20 22 24 26 28 30 32 34 


Slug-catcher design 

• Exploit pipeline’s slow response to transients 

‣ Reduce slug-catcher size 

• Onshore reception system routes liquid to 

off-spec tank 

‣ Optimise slug-catcher design 

Volume rate (m 3 /h) 

300 

200 

100 

0 

Liquid flow into slug-catcher 

0 2 4 6 8 10 12 14 

Time (days) 

36 - 



Pipeline integrity and leak detection 

37 

- 

Classification: Internal 2011-02-21 

Deepwater horizon


Probability reduction 

Consequence reduction 

Robust 

design 

Safe 

operation 

Integrity 

management 

Leak 

detection 

Emergency 

response 

38 - 



PPS and PPC 

39 - 



Risk reduction 

Allocations of risk reducing measures 

Achieved freq of 

overpressure 

Acceptable risk 

( Frequency of 

overpressure ) 

Frequency of 

overpressure 

Without risk reduction 

1x10 - 5 

1 times pr year 

•Facilities regulation §33 

•ISO 10418 (API 14 C) 

•IEC 61508 

•IEC 61511 

Required risk reduction 

Actual risk reduction 

PPS - 2 PPS - 1 PPC 

Manuel 

actions 

Frequency of 

overpressure 

PPC: Independent of the PSS 

Achieved risk reduction from safety functions 

PPS: Two independent systems activated at different pressure levels, and 

with a redundant and fail safe instrumentation and signal transfer system 

40 - 



Shut down of receiving facility 

Kollsnes export is stopped 0.5 hour later 

44" Den Helder. SOP at 2% Opflex. October 

Pressure, barg 

210 

200 

190 

180 

170 

160 

150 

140 

130 

120 

110 

100 

90 

Time, hrs 

0 2 4 6 8 10 12 14 16 18 

Kollsnes 

Den Helder 

Norwegian 

sector 

203 barg (+10m) 

Danish 

sector 

German 

sector 

156.8 barg (+10m) 

Dutch 

sector 

0 100 200 300 400 500 600 700 800 900 

Distance, km 

41 - 



Multi design pressure concept 

Normal Design 

Multi Design Pressure 

PD 

PD1 

Low utilisation of pipe material 

PD2 

Normal pressure profile 

Settle out pressure 

PD3 

Upstream end 

Downstream end 

Normal pressure profile 

• The settle out pressure in a “normal” shut-in situation shall not exceed the lower design 

pressure 

• The pipeline hydraulics during normal, upset and packing conditions are analysed to 

demonstrate that the pressure control and pressure protection system will act satisfactory 

• Cost saving material 

42 - 



Pipeline pressure protection 

43 - 




Probability reduction 

Consequence reduction 

Robust 

design 

Safe 

operation 

Integrity 

management 

Leak 

detection 

Emergency 

response 

protecting 

what? 

robustness 

need 

reliability 

technology 

solution 

pressure loss 

mass balance 

pipeline or 

zone? 

sensitivity 

point sensor 

acoustic 

44 - 



The risk picture… 

Probability 

Acceptable risk, but extra 

barriers? 

30” Kvitebjørn gas pipeline damage Consequence and leak, 2007 

45 - 



Key learning points 

• Complexity of field architecture development 

• Parameters influencing pipeline infrastructure development 

• Pipeline design premises 

• How the hydraulic of the pipeline system influence pipeline design 

• Pressure protection and leak detection of pipeline systems 

46 - 



Thank you 

Design of gas transport systems 

Elin Kristin Dale 

Senior Engineer Pipeline Transport Optimisation and Design 

ekrd@statoil.com , tel: +47 99 15 73 34 

www.statoil.com 

47 -

Design of Gas Transport Systems - NTNU

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