Crude oil

- composition and processing

2.9.2013

Tiina Komulainen

Based on Morten Holmager (2010), Offshore book – an introduction to the offshore industry, Offshore center Danmark.

Contents

• What is crude oil?

• Parameters

– Crude oil API-density

– sulfur content

– GOR

– WOR

• Design of oil separation

(topsides) process

• HSE

What is oil?

• Reservoir: mixture of – Gas components

– Oil components (light, heavy)

– Water

– Sand

• Separation – from multi-phase mixture to

crude oil (mixture of mainly oil components)

• Refining – From crude oil to products

like gasoline

Source: www.oilgaspath.blogspot.com

What is crude oil?

• Multi-phase flow from

reservoir typically a

mixture of:

– gas (C1 – C4)

– light oil /naptha (C5 – C9)

– paraffin oil (C10 – C16)

– diesel oils (C14 – C20)

– heavier oils(C20 – C70)

– asphaltene, bitume (C70+)

– sulphur

– water

– sand

Some important properties of oil components

Density ρ [kg/m3]

Viscosity μ [kg/ms], [cP]

Molecular weight M [g/mol]

Critical temperature TC [K]

Critical pressure PC [Pa]

Interaction with other components

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What is crude oil?

• Mixture of hundreds of oil compounds

• Reservoir multi-phase flow -> separation & stabilization -

> crude oil, produced water, gas (,sand)

• Crude oil -> refinery -> products

TRANSPORT TO REFINERY

What is oil – crude oil separation

• Separation of multi-phase fluid (emulsion) of oil, gas,

water and sand

• Three-phase separator with different internal

equipment

• Typically requires multi-stage separation for acceptable

crude oil quality

– Does not gasify under export conditions (T,P)

– Low water content

– No sand

Crude oil density: API gravity

• Density of separated oil,

«crude oil»

• American Petroleum

Institute (API)

• Density of crude oil

(@15.6 ºC) compared to

density of water

(~1000kg/m3)

– light crude: API >32

– medium crude 22<API<32

– heavy crude: API<22

Source: http://nesteoil.com/default.asp?path=1,41,538,2035,5196,5197,5199

5.131

60,60,

5.141

5.1315.141

API

2

FOHFcrude

spg

Crude oil sulfur content

• High temperature at refinery -> sulfur components form sulfur dioxide (SO2) -> exhaust gas -> acid rain (H2SO4)

• Sweet crude (Sulfur <0.5%)

• Sour crude (Sulfur> 0.5%)

• Examples – Brent Blend is a light, sweet North Sea

crude with a sulfur content of approximately 0.4%

– Russian Export Blend is a medium, sour crude oil with a sulfur content of approximately 1.2%

Source: http://nesteoil.com/default.asp?path=1,41,538,2035,5196,5197,5199

Exercise 1 – light/heavy, sweet/sour?

Crude source

Paraffins vol%

Aromatics vol%

Naphtenes wt%

Sulfur %

API Naphta yield

Nigerian-1

37 9 54 0,2 36 28

Saudi-1 63 19 18 2 34 22

Saudi-2 60 15 25 2,1 28 23

Venezuela-1

35 12 53 2,3 30 2

Venezuela – 2

52 14 34 1,5 24 18

USA-Mid.

- - - 0,4 40 -

USA, Texas

46 22 32 1,9 32 33

North Sea- Brent

50 16 34 0,4 37 31

Source: Offshore book, 2010, p.9

Crude oil quality: impact on refining

• The quality of crude oil => level of processing and conversion for optimal mix of products

• Light, sweet crude is more expensive than heavier, sourer crude

– requires less processing

– More value-added products, such as gasoline, diesel, and aviation fuel.

• Heavier, sourer crude

– Additional pumping & diluting costs

– Lower percentage value-added products with simple distillation

– Requires additional processing (=requires more energy) to produce lighter products.

Source: http://nesteoil.com/default.asp?path=1,41,538,2035,5196,5197,5199 Offshore book

Petroleum production - separation

• Gas/oil/condensate/water separation

• High to low pressure

• Many process units – oil separation (gravity

separator) and treatment

– water treatment

– gas compression

• Products – Stabilized crude oil (to

refinery)

– Gas

– Condensate

– (Prod. water, sand)

Sources: www.offshorecenter.dk www.iet-engineering.com

Separation train - design

• Oil composion – Heavy components hard to

separate

– Emulsion with water

– Gas entrainment

• Reservoir pressure & temperature

• GOR and WOR developement over the life time of the field – Gas to Oil Ratio increases

– Water to Oil ratio increases

Separation train - design

• Separation of

components between gas

and liquid: vapor – liquid

equilibrium (VLE)

– Component properties

– Surface between V-L

• Separation of liquid

components between oil

and water phase:

gravitation

– Settling time -> separator

length

Separation train - design

• Vapor-liquid equilibrium

– Temperature, pressure

– Properties of the components

– Simple calculation: Sandler’s

equation

Some important properties of oil components

Density ρ [kg/m3]

Viscosity μ [kg/ms], [cP]

Molecular weight M [g/mol]

Critical temperature TC [K]

Critical pressure PC [Pa]

Interaction with other components

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Separation train - design

• Settling time

– Geometry of the separator

– Density of the different

components -> gravity

– Breaking of the emulsion

(water-sand-oil)

Some important properties of oil components

Density ρ [kg/m3]

Viscosity μ [kg/ms], [cP]

Molecular weight M [g/mol]

Critical temperature TC [K]

Critical pressure PC [Pa]

Interaction with other components

ai [-]

Separation train - design

• Number of separation

stages

– Desired crude oil composition

– Inlet pressure, temperature

– Typically 3 stages

• High Pressure (50 - 125 atm)

• Medium/ Intermediate Pressure

• Low Pressure (1- 10 atm)

• (coalescer 1atm)

• Goal: Maximal amount of

stabilized crude oil

– Minimal amount of water and

gas

– Condensate from scrubbers

Petroleum production - refining

• Crude oil processing at

an oil refinery

– Distillation, cracking,

separation,…

– Energy consumption!

– Amount of products

– Depends on the crude

quality and processing

options available

Source: www.energyinst.org.uk

What is oil – gasoline?

— Crude oil processed at

a refinery => various

products

— Most valuable products:

— Gasoline, diesel,

kerosene

— Gasoline is a blend of

alkanes.

— Mainly C5-C10

— Single bindings between

C-atoms

— Formula CnH2n+2

18

Name (CnH2n+2)

Methane CH4

Ethane C2H6

Propane C3H8

Butane C4H10

Pentane C5H12

Heksane C6H14

Heptane C7H16

Octane C8H18

Nonane C9H20

Decane C10H22

Exercise 2 – separation of crude oil

Presentasjonens tittel 02.09.2013

• Why reservoir fluid needs

to be processed before

refining?

• Which factors determine

the sizing of the

separator?

• Which factors determine

price of the crude oil

(compared to Brent)

Petroleum production - HSE

• Sustainable development

– responsible energy

production

– environmental protection

• Health

• Safety

• Environment

• Regulations

– ISO

– API (USA)

– Norsok (Norway)

Source: blog.cifor.org/

Petroleum production - health

• Crude oil – Mixture of over 200 different

hydrocarbon compounds

– Extremely flammable

– Toxic, carsinogenic

– Major damage to health & environment

• Work environment – safety precautions

• gloves, safety glasses, jacket, laboratory fume hood, explosion proof equipment,…

– avoid heat, sparks, open flames

– tightly closed container, ventilated area

Source: www.sciencephoto.com

Petroleum production – safety

• Temperature, pressure at

different parts of the

production chain

– Quality of materials, safety

and automation system,

operators, all employees,

local communities

(pipelines, transport)

• Danger of explosion

– Material damages

• Case examples drilling

rigs, refineries, etc

Petroleum production - environment

• Preserving the environment

– improve air quality (flaring)

– preserve water resources (spills)

– protect biodiversity

• By

– responsible waste management

– prevention and manage of accidental

pollution

– Improving energy efficiency

– Development of renewable energy

sources

Source: www.greenpacks.org

Petroleum production HSE

• What kind of experiences on

HSE policies do you have?

• Why Health Safety and

Environmental requirements

are important in petroleum

production plants?

• How can HSE awareness be

improved by education /

internal courses?

Oil producers

Verdens største oljeprodusenter 2012 (kilde: Forbes):

1. Saudi Aramco - 12,5 Mbpd

2. Gazprom (Russia) 9,7- Mbpd

3. National Iranian Oil Co. - 6.4 Mbpd

4. ExxonMobil - 5.3 Mbpd

5. PetroChina - 4.4 Mbpd

6. British Petroleum - 4.1Mbpd

7. Royal Dutch Shell - 3.9Mbpd

8. Pemex (Mexico) - 3.6Mbpd

9. Chevron - 3.5Mbpd

10. Kuwait Petroleum Corp. - 3.2Mbpd

11. Abu Dhabi National Oil Co. - 2.9Mbpd

12. Sonatrach (Algeria) - 2.7Mbpd

13. Total (France) - 2.7Mbpd

14. Petrobras (Brazil) - 2.6Mbpd

15. Rosneft (Russia) - 2.6Mbpd

16. Iraqi Oil Ministry - 2.3Mbpd

17. Qatar Petroleum - 2.3Mbpd

18. Lukoil (Russia) - 2.2Mbpd

19. Eni (Italy) - 2.2Mbpd

20. Statoil - 2.1Mbpd

21. ConocoPhillips – 2.0Mbpd

22. Petroleos de Venezuela - 1.9Mbpd

23. Sinopec (China)- 1.6Mbpd

24. Nigerian National Petroleum - 1.4Mbpd

25. Petronas (Malaysia) - 1.4Mbpd

Petroleum production

• Landbased petroleum exploration and refining: http://www.youtube.com/watch?v=8W8SW98-sXQ

• Production in Texas http://www.youtube.com/watch?v=9Py8-Xy9MKo

• Subsea production: http://www.youtube.com/watch?v=apUgpNU-pC0

• Ormen Lange (gas production): http://www.youtube.com/watch?v=gz45mP7trmU&list=PL3D2FA93D808614CC&index=1

Source: www.oilgaspath.blogspot.com