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Challenges in CO 2 Pipeline
Design
Paul Crooks
Masdar: Abu Dhabi Future Energy
Panel on CO 2 Pipelines
27 September 2010

Introduction to Masdar – its Mission
• Masdar is Abu Dhabi’s future energy initiative
• It is a wholly-owned subsidiary of the Mubadala
Development Company

Introduction to Masdar – its Business
Units

Abu Dhabi CCS Project
• Create a national Carbon Capture,
Usage & Storage network
–CO 2 capture from power & industrial
sources
– Transportation pipelines
– Injection in oil reservoirs for EOR
• Technical potential for 30 million Tons
by 2030
• Phased approach:
Phase 1, ~6 million Tons of CO 2
• Build an early model of large scale
commercial stage application

CCS Project Phase 1 - FEED
• FEED Completed 2008 -2010 by Mustang / JPK
– Pressure: 90, 230, 245barg (min., MAOP, DP)
– Temperature: 13, 30, 65 o C (min., Normal, DT)
– Throughput: 6.2MT/a, CO 2 Dense Phase
• Pipeline Network:
– Design complete with all route approvals
– Initially 179km Pipeline, Additional 318km with Phase
development
–CO 2 sources: Steel, Processing and Power Industries
– Delivery to ADCO Oil Fields for EOR

CCS Project Phase 1 - FEED
• Significant challenges in Design & Material choices.
– Exacerbated by lack of Recommended Practices for
CO 2 Pipelines
• Challenges:
– Flow Modelling, Phase Issues and System Hydraulics
– Pipeline Operating Pressure, Running Ductile Fracture
and required Wall Thickness
– Risk Assessment and Dispersion Modelling
– Pipeline Design Factors and Population Densities
– Water content and Pipeline Integrity during Blowdown

Hydraulics and Flow Modeling
• CO 2 composition worst case used – Future-Proof Pipeline
– CO 2 composition > 95% purity - Balance: H 2 S, H 2 , CO, N 2 , O 2 , etc
• Static hydraulics: ASPEN HYSIS
– PR Equations of State – checked against NIST CO 2 properties
• Dynamic Flow Assurance: OLGA
– OLGA model – checked against NIST CO 2 properties
• Good comparison: 1% – 4% variation
• Surge analysis: within Design Margin (< 245barg)
• Hydraulic Flow Modeling Issues:
– Lack of validated CO 2 + Impurities Physical Properties data
– Lack of validated CO 2 Hydraulic Models with actual flow data
• Operating at high pressure: increased margin to uncertain areas
of physical data/modelling.

Operating Pressure, Ductile Fracture
and Pipeline Wall Thickness
• Operating & Design Pressure a function of:
– Min Pressure - 90barg (no two phase transition),
practically110barg
– Network line losses: 40-50barg
– Source Compression Power
• Pipeline Wall Thickness a function of:
– Hoop stress: 1500# in all cases
– Ductile Fracture Arrest: Wall thickness and toughness
of steel
• Masdar Design considered:
– PSL2 X65 Pipe, NACE, toughness values (27J – 60J)
;no premium for pipe
– Wall Thickness: Battelle Two Curve method

Operating Pressure, Ductile Fracture
and Pipeline Wall Thickness
“Race”
Velocity of crack propagation
And
Depressurization wave
Aim: Keep crack propagation velocity > Depressurization wave

Operating Pressure, Ductile Fracture
and Pipeline Wall Thickness
• For a Design Pressure of ~175barg
– WT CA
> WT HS
for readily available steels (toughness < 120J)
– Premium for material and operating below capacity of pipeline
• For a Design Pressure of 245barg
– WT HS
> WT CA
for steels with toughness: 27J and 60J
– No premium for material and operating at capacity of pipeline
• Benefits of High Pressure Design
– Compression at source, delivery to wellhead at ~170barg. Limited sink
compression required
– Line sizes for given throughput reduced
– Overall cost reduction for Pipeline Network Operations ref [King]
• Possible Disadvantages of Design
– Wall thickness limits vendors capable of ERW/SAW pipe
– More complex welding procedures: (wall thickness, NACE, high toughness)
– Perceived increased hazard of Operating at High Pressure

Risk Assessment & Dispersion
Modelling
• Risk Assessment by conventional methods
– Frequency assessment: leak data from hydrocarbon
industry
– Consequence Modelling: exposure criteria for lethality
• CO 2 dispersion based on conventional methods
– Release rates based on MAOP and postulated hole size
– Horizontal jet plume followed by passive dispersion
• But…
– The behaviour of CO 2 on release not like Hydrocarbon
– Lack of validated models to match plume behaviour with
reality

Risk Assessment & Dispersion
Modelling
• Release model behaviour determined in FEED:
– Ductile Fracture release model [King]
– Mustang/JPK Pipeline Blowdown Simulations
• CO 2 Consequence modelling effects therefore
conservative and potentially misleading
– Consequence dispersion: 235barg as compared to

• Start Pressure 175barg
• CO 2
rapidly moves from
single to multi phase
• Liquid/Vapour/Solid
• Discharge Pressure rapidly
settles < 80barg
• Highly Chocked flow with
low sonic velocity
• Phenomena occurs at
higher operating
pressures as well
• Discharge Pressure
rapidly < 80barg
• Start Pressure 245barg

• Full bore blowdown
• Rapid settle out to less than 60barg in
all cases
• Start Pressure 235barg

Pipeline Design Factors
• Pipeline design to B31.4
– Design Factor of 0.72 with no guidance on proximity
– Conservatively applied B31.8 criteria for Pipeline Location Class
• Majority of the Pipeline Route is Location Class 1 and OK
• Loc Class 3 & 4 areas:
– For High Pressure Op: Wall Thickness over ½ inch for 8, 12, 14inch Pipe
– Manufacturing issues for ERW pipe
• Consider Providing alternate protection methods aside from Pipe Wall
– Providing Concrete Slabs in Populated Loc Class 4 areas
– Providing Fibre Optic leak Detection throughout pipeline
• Optimisation of Pipeline Wall Thickness ongoing:
– Release of recent DNV Recommended Practice for CO 2
Pipelines
– Benefits of wall thickness > ½ inch
Design Factor Loc Class 1 Loc Class 2 Loc Class 3 Loc Class 4
B31.8 0.72 0.6 0.5 0.4
DNV RP J202 0.83 0.77 0.67 0.55

Water Content and Blowdown
• Avoidance free water in CO 2 systems well documented
– Need to consider Operating conditions and Environmental
conditions when setting water content
• US and European Design: water content typically

Water Content and Blowdown
• However - Design Issue associated with Blowdown
– Depending on blowdown rate: rapid cooling of the CO 2 stream,
Steel temperatures in area of Blowdown fall to -80 o C / -20 o C
– Maintenance Blowdown not time critical: reduce rate to ensure
temperatures remain above -29 o C
• For a 12” Pipeline, a typical Pipeline section between Block
Valves (32km) via 2” Blowdown Valve (for UAE conditions):
– Water Drop out occurs for initial water contents above 10lb/mmscf
– Reducing water content to less than 10lb/MMSCF involves
considerable CAPEX/OPEX
• For UAE conditions, design to 40lb/MMSCF and manage
Blowdown
– Manage Pipeline Blowdown to a rare occurrence
– Manage at reduced rate to avoid temperature impacts
– Nitrogen sweep after Blowdown to remove free water

• Reduced blowdown rate
ensures temperatures
remain above min pipe wall
temperatures

• Majority of water drop out resaturated
on recovery of Pipeline
Temp after Blowdown
• Water Drop out increases 7
fold above 40lb/mmscf initial
water content

Other Design/Operating Issues
• Other issues not specifically mentioned:
–CO 2 environment valve, gasket, etc materials
– Leak detection – use of Fibre Optics along with
SCADA
– Start-Up methodology and use of Nitrogen
– Pigging – no lubricated environment
– Booster Pumps vs Compression

Summary
• Design of CO 2 systems must consider safety
– Need for CO 2 system Design Guidance is critical
• Impact of impurities
– Hydraulics, Dew Point, Crack Propagation: Future Proof
• Pipeline operating pressure and wall thickness
– Ductile Fracture a controlling element
• CO 2 Dispersion modelling needs validation
– Behaviour of CO 2 in near field should be paramount
• Pipeline Design Factors
– Optimisation and use of alternates
• Initial Water content is application and environment specific
– In UAE – operation with higher water content: avoids high cost of
dehydration
– Need to control Blowdown is critical

Thank You for your attention