design of gas transport systems

8/17/2019 Design of Gas Transport Systems

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1 - Classification: Internal 2011-02-21

Design of Gas Transport Systems

October 10, 2012

Elin Kristin Dale

[email protected]

TPG4140 – NATURGASS, NTNU


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TPG4140 – NATURGASSNTNU


Design of gas transport systems

• Part 1:

− Intro 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


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3 - Classification: Internal 2011-02-21Photo credit: Manfred Jarisch / StatoilHydro

Part 1

Intro Transport technology


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Transport technology

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

Responsible for Transport technology in Statoil:

• Multiphase system and flow assurance (FA)

• Transport optimisation and design (TS)

Our job is to secure and optimize transport of oiland gas in pipeline systems


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Market

conditions

Reservoir

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 ofleak detection system (PM-vakt)

Transport technology

PLEM


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Gas/condensate fields- and infrastructuredevelopment


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Gas transport technology

BCM

LNG

GTL/Methanol

PIPELINE

UNECONOMIC

1000 2000 3000 4000 5000

Distance to market - Km

Floating LNG

Electricity(HVDC)

CNG

50

20

10

5

2

1

.50

Volume

(North sea)(Barents sea)


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• Statoil has developed the world’s largestoffshore gas pipeline network

• Technical services are provided by Statoil forthe world's most extensive submarine gaspipeline system:

− 7800 km pipelines (30” – 44”)

− Long term transport capacity approx.

365 MSm3

/d• Statoil is the leader in the construction of

large-diameter pipelines in deep water.

• On 1st January 2002, Gassco became theoperator for most of the gas pipeline systems

from the Norwegian continental shelf.• On 1st January 2003, Gassled became the

owner for most of the gas pipeline systems(Statoil share 5%, Statoil+Petoro share 50,8%).

The Norwegian Continental Shelf


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• 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

Gas/condensate fields- and infrastructure

development


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• The pipeline between X and Y isthe main link between theproduction at A and B and the

terminal E.• Utilisation of the XY link affects the

capacity towards E, creating abottleneck and a gap between theactual delivery and the demand.

• Routing of the gas will determinethe possible transportation capacityat a given scenario.

• The sum of exit capacity in atransport system is not necessarilyequal the actual transport capacity.

• Transport capacity is dependent onvolume scenario, bottlenecks anddependencies.

Production scenario 1 [MSm3/d]

Producers Exit terminals

A B C D E

30 40 10 15 65

A B C

D E

X Y

14,7 20 20 10

15 49,7

19,7

14,7

49,7

Gap: ~15

Existing infrastructure - capacity


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• Example of business case:

− New field discovery Johan Sverdrup,largest finding in the world this year.

500-1200 Mill barrels oil equivalents, 140km offshore, 112 meter depth, 1900meter below the seabed.

− Which field architecture will yourecommend to your management ?

Overall field architecture case – Johan Sverdrup

• 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 transportpath, 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.


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Pipeline system design

Terms and definitions


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• Pipeline system

− A pipeline with compressors or pump stations

− Pressure reduction stations

− Metering

− Tankage

−Supervisory control and data acquisition system (SCADA)

− Safety systems

− Corrosion protection systems

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

• Pipeline

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

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

Petroleum and natural gas indus tries

Pipeline transportation systems, ISO13623

Pipeline system design – terms and definitions


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• 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 beidentified and considered when defining the design conditions.

Petroleum and natural gas industries

Pipeline transportation systems, ISO 13623 OS F-101: Submarine PipelineSystems

Pipeline system design – system definition


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SCSSV

PMV

PWV

CHOKEBRANCH

HIPPS

MANIFOLD

SSIV

SSIV

CHECK

LANDFALL

PIG TRAP

PIG TRAP

PIG TRAP

PLEM

TEE

X-MASTREE

CHOKEMODULE

TEMPLATE ANDMANIFOLD

RISER BASE

CHECK + BLOCK

SUBSEAPROCESSING

UNIT

ESV

ESV

ESV

Platform/Floater

Onshore

SubseaProduction

Subsea connectionPipeline Systems:Single phase; Gas, Oil, condensate

Multiphase;

Subsea isolation

Pipeline systemsSubsea Production Systems (ISO 13628) and

Pipeline Transportation Systems (ISO 13623)


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Pipeline Project Organisation (Typical)

Project Manager

Pipeline

EngineeringSystem/RFO

Pipeline

Construction

Project Control

LandfallPreparation for

Operation

Authority

Procurement HSE

Administration EIA

Upstream

Platform/Terminal

Downstream

Platform/Terminal


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


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Thermo-

hydraulic

analysis

Internal diameter,

capacity, pressure

and temperature

profile, etc.

Functional

requirements;

gas routing,

regularity,

gas quality,

agreements

Functional

requirements,

Regularity,

Deliverability

Overall

Operational

Philosophy;

Control and

Safety

System,

Environment,

etc.

Pipeline System

Diagram, Process

Flow Diagram

Control and Safety

Philosophy

System design

concept

Boundary conditions and technical interface between platform – pipeline – terminal

P&ID’s

QA

Pipeline system design – work process


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20 - Classification: Internal 2011-02-21Photo credit: Manfred Jarisch / StatoilHydro

Part 2

Design premisesHydraulic capacity and gas quality


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• 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.

Pipeline system design – Hydraulic analysis 1/2


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• The hydraulics of the pipeline system should be analysed to demonstrate that thesystem can safely transport the fluids for the design conditions specified by thesystem definition, and to identify and determine the constraints and requirements for

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

• 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.

Pipeline system design – Hydraulic analysis 2/2


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• Pipeline Route

− Length

− Bathymetric profile

Area B - Åsgard Transport, Kårstø pressure

80

85

90

95

100

105

110

115

120

125

130

66 68 70 72 74 76 78 80 82 84 86

Hydraul ic capacity, MSm³/d

P r e

s s u r e ,

b a r g

High Rough Likely Rough Low Rough

Area B - Åsgard Transport, Kårstø temp.

-3

-1

1

3

5

66 68 70 72 74 76 78 80 82 84 86

Hydrauli c capacity, MSm³/d

T e m p e r a t u r e

, ° C

High Rough Likely Rough Low Rough

• Environmental Conditions

− Air temperature

− Sea bottom temperature

− Ground temperature

−Geo-technical data (soil conditions)

Pipeline system design – Design premises 1/3


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Variation o f parameters and hyd raulic capacity compared to basis

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

1

2

3

4

5

Gas Compositio n

Roughness 1- 3 micron

Temperature

Leng th +/-10 Km

Trenching -200 Km

10 mic ron

Zeebru gge 69.5 MSm³/d (october)

Hydraulic capacity – Sensitivity analysis


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• Pipeline Data

−Design pressure

− Design temperature

− Internal diameter

− Wall thickness

− Internal coating

− Concrete coating

− Insulation

− Trenching/dredging

− Gravel/rock dumping



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1200 km a 12m pipes:

Total pipeline steel(962 000 t)= 40 Troll A deck

Concrete coating(330 000 m3)= 1,5 Troll A GBS

Coating(25 000 t)= 3 Eiffel TowersTotal coating “wire”:(51 900km)= 1.3 timesaround the equator

Per pipe:

Ca 25 tonns

Langeled Bredero Shaw i Farsund Sept. 2004


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Solitaire:

The worlds largest pipeline layingvessel at Nyhamna

Acergy Piper:At Sleipner T at start-up of the layingprocess

The largest laying vessels


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• 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



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• Double expanding gate

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

• 10m high including activator:

• Total of 100 tons

Transport of 42” subsea pipeline

valve


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• Ensure interoperability /interchangeability (WI)

• Ensure unproblematic transport of gas

−Max/min temperature and pressure

• Prevent corrosion and erosion of equipment

− Water, CO2, H2S content

• Prevent condensation of liquid (HC dew point)

• Prevent gas hydrates (Water dew point)

Why gas quality specifications?

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


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System design of multiphase pipelines


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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

0

1000

2000

3000

4000

5000

6000

7000

8000

24 26 28 30 32 34Gas rate (MSm3/d)

L

i q u i d c o n t e n t ( m

3 )

Designrate

20

30

40

50

20 22 24 26 28 30 32 34

Gas rate (MSm3/d)

P

r e s s u r e d r o p ( b a

r a )

LargeID

SmallID

Designrate

SmallID

Large

ID

The diameter dilemma of long gas-condensate

pipelines


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Pipeline diameter: small

• Minimize liquid inventory

Accept moderate/high pressure drop

Slug-catcher size set by:

• Rate increase:From maximum turndown to designrate

• Pigging

Liquid inventory prior to pigging

20

30

40

50

20 22 24 26 28 30 32 34

Gas rate (MSm3/d)

P r e s s u r e d r o p ( b a r a )

Design pressuredrop

Designrate

Maximumturndown

0

1000

2000

3000

4000

5000

60007000

8000

24 26 28 30 32 34Gas rate (MSm3/d)

L i q u i d c o n t e n t ( m 3 )

Design

rate

Steady state

liquid contentMaximumturndown

S l u g - c a t c

h e r

v o l u m e

Troll slug-catcher

Conventional design of gas-condensate pipelines


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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

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

Liquid flow into slug-catcher

0 2 4 6 8 10 12 14Time (days)

300

200

100

0 V o l u m e

r a t e ( m 3 / h )

20

30

40

50

20 22 24 26 28 30 32 34

Gas rate (MSm3/d)

P r e s s u

r e d r o p ( b a r a )

LargeID

SmallID

New design of gas-condensate pipelines


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Pipeline integrity and leak detection

Deepwater horizon


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Robust

design

Safe

operation

Emergency

response

Integrity

management

Leak

detection

Probability reduction Consequence reduction


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PPS and PPC


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Allocations of risk reducing measures

Frequency of

overpressure

Frequency of

overpressure

Without risk reduction

Acceptable risk

(Frequency of

overpressure )

1 times pr year1x10 -5

Achieved freq of

overpressure

Required risk reduction

Achieved risk reduction from safety functions

PPS -2 PPS -1 PPCManuel

actions

•Facilities regulation §33•ISO 10418 (API 14 C)

•IEC 61508

•IEC 61511

Actual risk reduction

PPC: Independent of the PSS

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

with a redundant and fail safe instrumentation and signal transfer system

Risk reduction


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Shut down of receiving facility

Kollsnes export is stopped 0.5 hour later 44" Den Helder. SOP at 2% Opflex. October

90

100

110

120

130

140

150

160

170

180

190

200

210

0 100 200 300 400 500 600 700 800 900

Distance, km

P r e s s u r e

, b a r g

0 2 4 6 8 10 12 14 16 18Time, hrs

203 barg (+10m)

156.8 barg (+10m)

Den Helder

Kollsnes

Norwegiansector

Danishsector Germansector Dutchsector


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Normal pressure profile

Low utilisation of pipe material

PD

Upstream end Downstream end

Normal Design

Settle out pressure

Normal pressure profile

PD2

PD1

PD3

Multi Design Pressure

• 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

Multi design pressure concept


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EV

PPS-1 PPS-2

PT PT

Pipeline

EV

Upstream

Plant

Downstream

Plant

PT PT

PPS-1 PPS-2

Triple redundant

Fiberoptic and

telemetry

EVEVEV

PPS-1 PPS-2PPS-1 PPS-2

PT PTPT PTPTPT PTPT

Pipeline

EV

Upstream

Plant

Downstream

Plant

PT PTPT PTPTPT PTPT

PPS-1 PPS-2PPS-1 PPS-2

Triple redundant

Fiberoptic and

telemetry

Pipeline pressure protection


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Robust

design

Safe

operation

Emergency

response

Integrity

management

Leak

detection

Probability reduction Consequence reduction

need

protecting

what?

pipeline or

zone? sensitivity

robustness

reliability

technology

solution

mass balance

pressure loss

point sensor

acoustic


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The risk picture…

Probability

Consequence

Acceptable risk, but extrabarriers?

30” Kvitebjørn gas pipeline damage and leak, 2007


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• 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

Key learning points


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design of gas transport systems

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