03 - Pipeline Hydraulics
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Transcript of 03 - Pipeline Hydraulics
Shawn Kenny, Ph.D., P.Eng.Assistant ProfessorFaculty of Engineering and Applied ScienceMemorial University of [email protected]
ENGI 8673 Subsea Pipeline Engineering
Lecture 03: Pipeline Hydraulics
2 ENGI 8673 Subsea Pipeline Engineering – Lecture 03© 2008 S. Kenny, Ph.D., P.Eng.
Lecture 03 Objective
To provide an overview of flow assurance To provide simple tools for assessing single phase flow pipeline hydraulics
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Overview Flow AssuranceSystem Deliverability
Line sizing Production ratePressure profile and boosting
Thermal BehaviourTemperature profilePassive or active mitigation
Product ChemistryWaxing, asphaltenesHydratesScaling, erosion, corrosion
Operability CharacteristicsSteady-state, transientShut-down, start-up
System PerformanceMechanical integritySystem reliability
Ref: McKechnie et al. (2003)Ref: Watson et al. (2003)
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Flow Assurance HazardsMechanical
CorrosionErosion
FlowSluggingEmulsion
DepositionScalingSandWax & asphaltenesHydrates
Ref: Hydro (2005)
Ref: BakerHughes (2005)
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Flow Assurance StrategiesMechanical
Hydraulics•
Line sizing
•
Pumping, compressor•
Chillers, heaters
Processing•
Dehydration
•
Chemical removalIntervention•
Inline pigging
•
Plug removal
Ref: Hydro (2005)
Ref: Rosen (2005); Paragon (2005)
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Flow Assurance StrategiesThermal
BurialInsulationHeating
Ref: Hydro (2005)
Panarctic Drake F-76 Flowline Bundle
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Overview Flow Assurance
Lecture FocusOverview of steady-state, single phase flow
Associated Technical IssuesMultiphase, dense flowTransient flowStart-up, shut-down conditionsRisk and mitigation strategies
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Key Engineering Factors
Pipeline HydraulicsLine Sizing•
Primary function for product transport
Steady-State Conditions•
Operating pressure & temperature profile
Facilities Design•
Slug catcher, tank farm
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Drivers
Production RateFlow rate, throughputVelocity, pressure
Operating Cost ⇓ D ∝ losses & Δpressure
Construction Cost⇑ D
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Hydraulics – Key Input ParametersProduct Characteristics
Phase & compositionChemical constituents
Pipeline ConfigurationRoute lengthNominal diameterBathymetric & topographic profile
Thermal ProfilePipeline, soil conductivityAir, water temperature
Initial Boundary ConditionsInlet pressure, temperatureOutlet pressure, temperature
Ref: Terra Nova DPA
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Fluid Mechanics
Single Phase FlowOil, gas or waterNewtonian fluid•
Some heavy oils are non-Newtonian
Constant Flow RatePressureGravity
Pressure Term
Nominal Pipeline Radius
Velocity Profile Shear Stress
Elevation
Elemental Length
Ref: White (1986)
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Single Phase Flow Mechanics
Uniform Velocity
Shear Stress
Pressure Term
Pipeline Radius
Velocity Profile Shear Stress
Elevation
Elemental Length
( )2 22 0dZr dP r dL g r dLdL
π τ π ρ π+ + =
2 0dP dZgdL r dL
τ ρ= − − =
2
2f uρτ =
2
0dP f u dZgdL r dL
ρ ρ∴ = − − =
• f
≡
Fanning friction factor• u ≡
mean velocity• ρ ≡ fluid density
Ref: White (1986)
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Integral Formulation
If Constant Over dLDiameterVelocityFriction (viscosity)Density (gas flow)
Pressure Term
Pipeline Radius
Velocity Profile Shear Stress
Elevation
Elemental Length
2
0dP f u dZgdL r dL
ρ ρ= − − =
( ) ( )2
2 1 2 1 2 1 0f uP P L L g Z Zr
ρ ρ− = − − − − =
Ref: White (1986)
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Integral Form Not PracticalVariation in Properties
Velocity, density, friction coefficientOil and Gas Flow
Heat loss •
f ∝
Re ≡ μ(T)Gas Flow
Density•
Δρ
∝
ΔP ≡ ΔQ & ΔzConstant mass flow rate•
ΔU ∝ Δρ
CompressibilityJoule-Thompson (⇓T ∝ ⇓P)
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Frictional Losses
AssumptionsSmooth, uniform internal diameterIncompressible fluidFunction of Reynolds number•
μ ≡ viscosity (Pa s)
Re U Dρμ
=
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Frictional Losses (cont.)Friction Coefficient
Fanning [f]•
Hydraulic radius
Manning [m]•
Diameter
•
m = 4fParameters
•
Reynolds
number, Re
•
Surface roughness, k
k ≈ 0.05mmCorrosion, erosion, wax, etc.
Re16
=f
( )101 4 log Re 0.4ff
= −
0.3240.0014 0.125Ref −= +
Loss ∝
U
Loss ∝
D
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Analysis of Turbulent Flow
Theoretical TreatmentEmpirical coefficientsSensitive to surface roughness
0.75 0.25 1.75
4.75
0.241L QPD
ρ μΔ =
Ref: White (1986)
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Pipeline Hydraulics Calculations
Energy Balance per Unit Lengthmass flow rate (kg/s)
Δh change in enthalpy (J/kg)ΔEPE change in potential energy (J/kg)ΔEKE change in kinetic energy (J/kg)ΔQT heat loss (W)ΔW external mechanical work (W)
( )Δ +Δ +Δ +Δ + Δ = 0PE KE Tm h E E Q W
m
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Line Sizing – Gas Flow
Panhandle A FormulaEmpiricalLarge diameter pipelinesRelatively low pressure (7MPa)
1.07881 0.53943 0.4606 2.61821 2438 10 o
o
T p pQ E G Dp LT
− −⎛ ⎞ ⎛ ⎞−= × ⎜ ⎟ ⎜ ⎟
⎝ ⎠⎝ ⎠• Q
≡
Flow rate (m3/day)• E ≡
efficiency factor (typically 0.92)• po
≡
Reference pressure (MPa)• To
≡
Reference temperature (K)• p1
≡
Upstream pressure (MPa)• p2
≡
Upstream pressure (MPa)
• L
≡
Pipeline length (km)• T ≡
mean temperature (K)• G
≡
gas gravity (air = 1)• D
≡
pipeline diameter (mm)
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Line Sizing – Oil Flow
Rule of ThumbTrade-off CAPEX ⇔ OPEX
D ≡ in; Q ≡ BBL/day1 BBL = 42 US gal = 35 Imp gal1 BBL = 158.97 L
D ≡ mm; Q ≡ m3/s500QD =
840D Q=
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Example 3-01
Calculate the line size (nominal diameter) for a horizontal, single phase oil pipeline
Flow rate, Q = 0.342 m3/sFluid density, ρ = 950 kg/m3
Viscosity, ν = 2 ×10-5 m2/s = 20 centistokesSurface roughness, k = 0.006mmPipeline segment length, L = 100mHead loss, hf = 8m
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Example 3-01 (cont.)
Modified Moody Chart
Ref: White (1986)
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Example 3-01 (cont.)
Using Modified Moody Chart
Corresponds to smooth wall
Line size
ν −= × 93.51 10kQ
βπ υ
−= = ×3
113 5
128 2.012 10ghQL
β= =0.416Re 1.43 72,100
ν π ν= =
4Re UD QD
⇒ = 0.302D m
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Example 3-02
Consider the following pipeline system transporting 100kBBL/day single phase oil
Oil density, ρ = 850 kg/m3
Viscosity, μ = 0.01 Pa·s = 10 centipoiseInlet pressure 5MPaArrival pressure 1MPa
Calculate the line size for a 25km pipeline
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Example 3-02 (cont.)
Line Sizing Rule of Thumb
Using API 5L (2007)Select D = 12″ (12.75″) = 323.9mm•
Guess WT = 12.7mm
100000 14.1" 358500 500QD mm= = = ⇒
( )-
3
2 2
0.184 / 2.63 /0.3239 2 0.0127
4
Q m sU m sA mπ
= = =×
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Example 3-02 (cont.)
Reynolds Number
Fanning Friction FactorAssume k = 0.001•
f = 0.0059
( )( )( )34
850 2.63 0.3239 2 0.0127Re 6.67 10
0.01kg m m s m mU D
Pa sρ
μ
− ×= = = ×
⋅
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Example 3-02 (cont.)
Check Erosion VelocityReduces wall thicknessGenerates noiseEmpirical expression
max
3
122 122 4.2850
mUskg
mρ
= = =
max2.63 4.2m mU U oks s
= < = ∴
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Example 3-02 (cont.)
Pressure Drop
Friction loss only
Allowed ΔP = 5MPa – 1MPa = 4MPa•
∴
Reselect D
( )( ) ( )232 0.0059 850 2.63 250005.81
0.14925kg m m s mf U LP MPa
r mρ
Δ = = =
2
0dP f u dZgdL r dL
ρ ρ= − − =
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Example 3-02 (cont.)
Using API 5L (2007)Select D = 14″ = 355.6mm•
Assume WT = 12.7mm
Acceptable ΔP
20.29852.63 2.150.3302
Q m m mUA s m s
⎛ ⎞= = =⎜ ⎟⎝ ⎠
( )( )( )34
850 2.15 0.3302Re 6.03 10
0.01kg m m s mU D
Pa sρ
μ= = = ×
⋅
( )( ) ( )232 0.006 850 2.15 250003.57
0.1651kg m m s mf U LP MPa
r mρ
Δ = = =
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Example 3-02 (cont.)
Field Life ScenarioReduced production rate•
10 years
•
20kBBL/day
Produced water•
CO2
, H2
S
Potential •
Water drop out
•
Extensive corrosion at clock position 6 and low spots
202.15 0.43100
Q m kBBL day mUA s kBBL day s
⎛ ⎞= = =⎜ ⎟
⎝ ⎠
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Multiple Phase FlowPhase
GasLiquid (oil, water)Solid (sand)
Flow RegimeMultiple modesIrregular flowVibration
EmulsionOil and water mixture ⇑ Viscosity ∝ ⇑ ΔP
SluggingHydrodynamic, elevation inducedProcess upset, shut down
Surge⇑ Volumetric, mass flow rates
Ref: Hydro (2005)
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Reading List1.
Cochran,S. (2003). Recommended Practice for Hydrate Control and Remediation. World Oil, September, pp.56-65.
[2003_Cochran_RP_Hydrate_Control_Remediation.pdf]
2.
McKechnie, J.G.and
Hayes, D.T. (2003). Pipeline Insulation Performance for Long Distance Subsea Tie-Backs. 14p. [2003_McKechnie_Insulation_Performance_Long_Distance_Tie_
Backs.pdf]
3.
Wasden, F.K. (2003). Flow Assurance in Deepwater Flowlines/Pipelines. Deepwater Technology, October, pp.35-38.
[2003_Wasden_FA_Deepwater_Flowlines.pdf]
4.
Watson, M., Pickering, P. and Hawkes, N. (2003). The Flow Assurance Dilemma: Risk versus Cost? E&P, May, 4p. [2003_Watson_Flow_Assurance.pdf]
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ReferencesAPI 5L (2007). Specification for Line Pipe, Forty-fourth Edition. 44th
Edition.BakerHughes (2005). http://www.bakerhughes.com/bakerpetroliteHydro (2005). http://www.hydro.com/ormenlange/enParagon (2005). http://www.paraengr.comRosen (2005). http://www.roseninspection.netRidao, M.A. (2004). “Optimal use of DRA in oil pipelines”. IEEE International Conference on Systems, Man and Cybernetics, pp.6256-6261. Watson, M., Pickering, P. and Hawkes, N. (2003). The Flow Assurance Dilemma: Risk versus Cost? E&P, May, 4p.White, F.M. (1986). Fluid Mechanics. 2nd Edition, McGraw-Hill, ISBN 0-07-069673-X, 732p.