Shawn Kenny, Ph.D., P.Eng. spkenny@munspkenny/Courses/Undergraduate/ENGI8673/Lecture... · Slug catcher, tank farm ... Line Sizing – Oil Flow Rule of Thumb

Shawn Kenny, Ph.D., P.Eng.Assistant Professor

Faculty of Engineering and Applied ScienceMemorial University of Newfoundland

[email protected]

Lecture 04 – Flow Assurance

ENGI 8673 Subsea Pipeline Engineering – Lecture 04© 2009 S. Kenny, Ph.D., P.Eng.

Lecture Goals

Students will be able to: identify key factors influencing flow assurance,

hydraulic and thermal analysis of product flow in pipeline systems, and

use simple tools for assessing single phase flow pipeline hydraulics and thermal analysis

2


Reading List

3

# Document

4.1 Cochran,S. (2003). Recommended Practice for Hydrate Control and Remediation. World Oil, September, pp.56-65. [2003_Cochran_RP_Hydrate_Control_Remediation.pdf]

4.2 Wasden, F.K. (2003). Flow Assurance in Deepwater Flowlines/Pipelines. Deepwater Technology, October, pp.35-38. [2003_Wasden_FA_Deepwater_Flowlines.pdf]

4.3 Watson, M., Pickering, P. and Hawkes, N. (2003). The Flow Assurance Dilemma: Risk versus Cost? E&P, May, 4p. [2003_Watson_Flow_Assurance.pdf]

4.4 Geertsen, C. and Offredi, M. (2000). Highly Thermally Insulated and Traced Pipelines for Deepwater. 12th Deep Offshore Technology Conference, New Orleans, USA, 13p.[2000_Geertsen_Insulated_Traced_Deepwater_PL.pdf]

4.5 Maksoud, J. (2004). Petro-Canada Investigates Flow Assurance Challenges. Offshore, pp.112-113. [2004_Maksoud_ FA_Challenges_Petro_Canada.pdf]

1

2

3


Overview Flow Assurance System Deliverability

Line sizing Production rate Pressure profile and boosting

Thermal Behaviour Temperature profile Passive or active mitigation

Product Chemistry Single, multiple phase Waxing, asphaltenes Hydrates Scaling, erosion, corrosion

Operability Characteristics Steady-state, transient Shut-down, start-up

System Performance Mechanical integrity System reliability

4

Ref: McKechnie et al. (2003)


Flow Assurance Hazards Mechanical

Corrosion Erosion

Flow Slugging Emulsion

Deposition Scaling Sand Wax & asphaltenes Hydrates

5

Ref: Hydro (2005)

Ref: BakerHughes (2005)


Flow Assurance Strategies Mechanical

Hydraulics Line sizing Pumping, compressor Chillers, heaters

Processing Dehydration Chemical removal

Intervention Inline pigging Plug removal

6

Ref: Hydro (2005)Ref: Rosen (2005)

Ref: Paragon (2005)

4

5

6


Flow Assurance Strategies Thermal

Burial Insulation Heating

7

Ref: Hydro (2005)

Panarctic Drake F-76 Flowline Bundle


Flow Assurance Strategies Flow Performance

Drag reduction Drag reducing

agents (DRA) Liners

Inhibitors Methanol Mono-ethylene

glycol (MEG)

8

Ref: Hydro (2005)

Ref: BakerHughes (2005); Ridao (2004)


Pipeline Hydraulics – Goals Line Sizing

Primary function for product transport Transport rate (e.g. MMBBL/day, m3/day) Pressure

Steady-State Conditions Operating pressure & temperature profile

Facilities Design Slug catcher, tank farm Compression, chillers

9

7

8

9


Pipeline Hydraulics – Drivers Operating Cost

⇓D ∝ frictional losses & ∆pressure

Construction Cost ⇑ D

10


Pipeline Hydraulics – Key Parameters Product Characteristics

Phase & composition Chemical constituents

Pipeline Configuration Route length Nominal diameter Bathymetric & topographic

profile Thermal Profile

Pipeline, soil conductivity Air, water temperature

Initial Boundary Conditions Inlet pressure, temperature Outlet pressure, temperature

11

Ref: Terra Nova DPA


Fluid Mechanics – Single Phase Flow Parameters

Oil, gas or water Newtonian fluid

Some heavy oils are non-Newtonian

Constant Flow Rate Pressure Gravity

12

Pressure Term

Nominal Pipeline Radius

Velocity Profile Shear Stress

Elevation

ElementalLength

Ref: White (1986)

10

11

12


Fluid Mechanics – Single Phase Flow

Uniform Velocity

Shear Stress f – Fanning factor u – mean velocity ρ – fluid density

13


Fluid Mechanics – Integral Formulation

If Constant Over dL Diameter Velocity Friction (viscosity) Density (gas flow)

14


Integral Form Not Practical Variation in Properties

Velocity, density, friction coefficient Oil and Gas Flow

Heat loss f ∝ Re ≡ µ(T)

Gas Flow Density

Δρ ∝ ΔP ≡ ΔQ & Δz Constant mass flow rate

ΔU ∝ Δρ Compressibility Joule-Thompson (⇓T ∝ ⇓P)

15

13

14

15


Frictional Losses

Assumptions Smooth, uniform internal diameter Incompressible fluid Function of Reynolds number

µ ≡ viscosity (Pa·s)

16


Frictional Losses (cont.) Friction Coefficient

Fanning [f] Hydraulic

radius Manning [m]

Diameter m = 4f

Parameters Reynolds

number, Re Surface

roughness, k k ≈ 0.05mm Corrosion,

erosion, wax, etc.

17

Loss ∝ U

Loss ∝ D


Energy Balance Per Unit Length ≡ mass 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)

18

16

17

18


Line Sizing – Gas Flow Panhandle A Formula

Empirical Large diameter pipelines Relatively low pressure (7MPa)

19

• 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)


Line Sizing – Oil Flow Rule of Thumb

Trade-off CAPEX ⇔ OPEX

D ≡ in; Q ≡ BBL/day 1 BBL = 42 US gal =

35 Imp gal 1 BBL = 158.97 L

D ≡ mm; Q ≡ m3/s

20


Example 4-01

Consider the following pipeline system transporting 100kBBL/day single phase oil Oil density, ρ = 850 kg/m3 Viscosity, µ = 0.01 Pa·s = 10 centipoise Inlet pressure 5MPa Arrival pressure 1MPa

Calculate the line size for a 25km pipeline

21

19

20

21


Example 4-01 (cont.) Line Sizing Rule of

Thumb

Using API 5L (2007) Select D = 12″ (12.75″) Select D = 323.9mm Guess WT = 12.7mm

22

U =QA=

0.184m3 / sπ4

0.3239 - 2 × 0.0127( )2m2

= 2.63m / s


Example 4-01 (cont.)

Check Erosion Velocity Reduces wall thickness Generates noise Empirical expression

23


Example 4-01 (cont.) Reynolds Number

Fanning Friction Factor Assume k = 0.001

f = 0.0059

24

22

23

24


Example 4-01 (cont.)

Pressure Drop

Friction loss only

Allowed ΔP = 5MPa – 1MPa = 4MPa ∴ Reselect D

25


Example 4-01 (cont.) Using API 5L (2007)

Select D = 14″ = 355.6mm Assume WT = 12.7mm

Acceptable ΔP26


Example 4-01 (cont.) Field Life Scenario

Reduced production rate 10 years 20kBBL/day

Produced water CO2, H2S

Potential Water drop out Extensive corrosion at clock position 6 and low spots

27

25

26

27


Multiple Phase Flow Phase

Gas Liquid (oil, water) Solid (sand)

Flow Regime Multiple modes Irregular flow Vibration

Emulsion Oil / water

mixture ⇑ Viscosity ∝ ⇑ ΔP

Slugging Hydrodynamic,

elevation induced Process upset,

shut down Surge

⇑ Volumetric, mass flow rates

28

Ref: Hydro (2005)


Heat Transfer Mechanisms Conduction

Direct contact Relatively inefficient

Convection Flow or circulation

Natural or forced (advection)

Radiation Electromagnetic

energy Emissivity

Ability to absorb and radiate energy

29


Thermal Effects Flow Assurance

Viscosity effects on pressure drop Process facilities Wax, asphaltene, hydrate formation

Material behaviour Reduced strength Corrosion rates Creep

Mechanical design Thermal expansion Upheaval, lateral buckling

Shut-in & start-up operations Flow assurance Axial walking, ratcheting

30

28

29

30

ENGI 8673 Subsea Pipeline Engineering – Lecture 04© 2009 S. Kenny, Ph.D., P.Eng.31


Heat Transfer – Conduction Fourier Law

Q ≡ heat loss per unit length (W/m)

t ≡ time (s) k ≡ material thermal

conductivity (W/m/K) S ≡ surface area (m2) T ≡ temperature (K) U ≡ heat transfer

coefficient (W/m2-K)

32


Heat Transfer – Steady State

Integrate per Unit Length Annular layer Temperature gradient

33

QT

r dr, ΔT

31

32

33


Heat Transfer – Multiple Layers

Heat Transfer Coefficient

34


Heat Transfer – Soil Effects

Buried Pipeline ri ≡ inside pipe radius ro ≡ outside pipe

radius in contact with the soil

35


Thermal Conductivity Parameters

Common Materials (W/m/K) Steel 45 Concrete 1.2 Soil 1.0–2.0 Neoprene 0.26 PP syntactic 0.15–0.20 PU syntactic 0.10–0.15 PU light foam 0.02–0.03

36

34

35

36


Heat Transfer Coefficient

Non-insulated Single Wall 25 W/m2K Burial decrease U by

~1/3 Pipeline Bundle

≈ 1.5–2.5 Insulated Pipe-in-Pipe

≈ 3.0.–6.0 Insulated Pipe-in-Pipe

≈ 0.5–1.0

37


Steady State Thermal Profile

Parameters m – mass flow rate (kg/s) U – heat transfer coefficient (W/m2-K) Cp – specific heat capacity (J/kg-K)

Oil ≡ 1800 and Gas ≡ 2500 T0 – ambient temperature (°C) T1 – pipeline temperature at section 1 (°C) T2 – pipeline temperature at section 2 (°C)

38


Ref: Maksoud (2004)

37

38

39


Ref: Maksoud (2004)


Example 4-02

Calculate the heat loss coefficient (U) for an in-air, single wall, steel linepipe with no external or internal coatings. Do = 508mm t = 12.7mm k = 45 W/m/K

41


Example 4-03 Calculate the heat loss

coefficient (U) for the following pipe-in-pipe system Inner Pipe

Do = 406.4mm t = 17.5mm k = 45 W/m/K

Polypropylene Foam t = 45mm k = 0.22 W/m/K

Casing t =12.7mm k = 45 W/m/K

42

40

41

42




43

44

45


References API 5L (2007). Specification for Line Pipe, Forty-fourth Edition. 44th

Edition. BakerHughes (2005). http://www.bakerhughes.com/bakerpetrolite Hydro (2005). http://www.hydro.com/ormenlange/en Paragon (2005). http://www.paraengr.com Rosen (2005). http://www.roseninspection.net Maksoud, J. (2004). Petro-Canada Investigates Flow Assurance

Challenges. Offshore, pp.112-113. Ridao, 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.

46 46

Documents

Shawn Kenny, Ph.D., P.Eng. spkenny@munspkenny/Courses/Undergraduate/ENGI8673/Lecture... · Slug catcher, tank farm ... Line Sizing – Oil Flow Rule of Thumb