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Comparison of the Corrosivity of Dilbit and Conventional Crude

A Presentation to the Committee for

A Study of Pipeline Transportation of Diluted Bitumen

National Academy of Science

Washington, DC July 23-24, 2012

John Zhou, Ph.D., P. Geol., Executive Director, Environmental Management

Alberta Innovates - Energy & Environment Solutions (AI-EES)

Jenny Been*, Ph.D., P. Eng., PMP, former Group Leader, Corrosion Engineering

Alberta Innovates – Technology Futures (AI-TF)

(*Now with TransCanada Pipelines Ltd.)

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Alberta Innovates – Energy and

Environment Solutions (AI-EES)

Who we are?

• Technology arm of the Alberta Government in energy and environment

• One of four Alberta Innovates corporations

What we do?

Position Alberta for the future in energy and environment:

• Identify the technology needs for sustainable development & environmental protection

• Evaluate and select technologies and partners

• Invest in research & technology with industry & international collaborators

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What We Have Learned from the Review

• In the context of pipeline transportation, characteristics of dilbit are not unique and are comparable to conventional crude oils

• Comparison of equivalent crude oil

transportation systems shows no evidence that dilbit causes more failures or internal corrosion than conventional crudes

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Introduction

Transmission pipeline system

• Links secure and growing supply in Western Canada with the largest refining markets in North America

• Crude obtained from oil sands is too viscous to transport by pipeline and needs to be diluted with diluent dilbit

Diluted bitumen (Dilbit) = Bitumen + Diluent

Diluent:

• 25-30 v% in dilbit

• Made of light hydrocarbons such as gas condensate

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Introduction

• As part of the Keystone XL application the US Department of State (DOS) conducted a comprehensive environmental impact review

• The DOS issued a Final Environmental Impact Statement, Aug 26, 2011

Reaffirmed the environmental integrity of the project

Concluded that dilbit does not have unique characteristics and should not be more corrosive

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Objectives of the Study

• Summarize the concerns that have been raised

• Review the corrosivity of dilbit in transmission pipeline transportation as compared to conventional oil

• Describe and analyze the current scientific information to assess the validity of the concerns

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Concerns on and Claims against Pipeline Transportation of Dilbit

1. Dilbit contains 15 - 20 times higher corrosive acid concentrations

2. Dilbit contains 5 - 10 times more sulfur

3. Dilbit has a high concentration of chloride salts

4. Dilbit contains more abrasive sand particles, which can erode the pipelines

5. Dilbit can be up to 70 times more viscous, leading to higher temperatures

6. The Alberta pipeline system has had ~16 times as many spills, due to internal corrosion, as the U.S. system

7. Dilbit pipelines have an increased risk of internal corrosion due to dilbit sediment composition and characteristics

8. Chemical corrosion combined with physical abrasion can increase the rate of dilbit pipeline deterioration

9. Dilbit pipelines operate at higher temperatures, which would significantly increase the corrosion rate

10.Dilbit pipelines canhave a higher incidence of external stress corrosion cracking

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Quality Control of Dilbit Entering Pipelines

• Government:

Regulatory pipeline tariffs by National Energy Board and Federal Energy Regulatory Commission contain petroleum quality specifications (viscosity, density, etc.)

• Crude Quality Inc (CQI):

Manages crude quality information

Data publicly available on www.crudemonitor.ca

Conventional heavy and light crudes, sweet and sour crudes, dilbits

• Canadian Association of Petroleum Producers (CAPP):

Addresses on an ongoing basis the management of oil quality issues and issues in refining and shipping of crudes

Quality specifications of the condensate stream

• Canadian Crude Quality Technical Association (CCQTA):

Test methods and research

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• Pipeline Operators:

Manage and control the quality of crude during transportation

Crude is transported in batches according to a ranking order

Turbulent flow minimizes the mixing area between batches

Buffers or interface pigs prevent mixing between batches

Maximization of batch size

Minimization of start/stop operations

Minimization of contamination in tanks

Quality Control of Dilbit Entering Pipelines (Cont’d)

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Dilbit and Conventional Oil Crude Properties: the Comparisons

• All data (except viscosity) come from www.crudemonitor.ca

• Comparisons are made between 11 conventional crudes and 4 dilbits

• Conventional crudes: light, medium, and heavy from the Western Canadian Sedimentary Basin (WCSB)

• Dilbit:

Dilbit A from SAGD

Dilbits B and C from CSS (has been pipelined for 25 years)

Dilsynbit A from mining operations, partially upgraded

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0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

TAN

, mgK

OH

/g

Concern #1: Acid Concentration in Dilbit

Claim: Dilbit contains fifteen to twenty times higher corrosive acid concentrations than conventional crude oil

Data and Analysis

Total acid number (TAN)

of dilbit overlaps with that

of conventional crude

Naphthenic acids can be

corrosive at refinery

temperatures greater than

220oC (428oF)

Too stable to be corrosive

at transmission pipeline

temperatures

Summary: TAN in dilbit overlaps with that of conventional crude but it does not lead to more corrosion at transmission pipeline temperatures.

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Concern #2: Sulfur Content in Dilbit Claim: Dilbit contains five to ten times as much sulfur as conventional crudes; the

additional sulfur can lead to the weakening or embrittlement of pipelines

Data and Analysis

Sulfur content in dilbit

overlaps with that in

conventional crude

Elevated sulfur content does

not directly contribute to

corrosion (needs to be

converted to H2S)

Refinery conditions are

required for sulfur to be

converted to H2S

Summary: Dilbit sulfur content overlaps with conventional crude. Organically bound sulfur is too stable to be corrosive at transmission pipeline temperatures.

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Sulf

ur,

wt%

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Concern #3: Chloride Salt Concentration in Dilbit

Claim: Dilbit has a high concentration of chloride salts, which can lead to chloride stress corrosion cracking in high temperature pipelines

Data and Analysis

Dilbit has some of the lowest

chloride concentrations

Upgrading and processing

temperatures >150oC

(302oF) can result in the

formation of HCl; but not at

transmission pipeline

temperatures

Cl-SCC has not been

observed in carbon steel

transmission pipelines

Summary: Dilbit has some of the lowest chloride concentrations and Cl-SCC is not a problem for carbon steel or at transmission pipeline temperatures.

0

50

100

150

200

250

300

350

400

Ch

lori

de

Sal

ts, p

pm

w

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Concern #4: Sediment Content of Dilbit

Claim: Oil sands crude contains higher quantities of abrasive quartz sand particles than conventional crude, which can erode the pipelines

Data and Analysis

Dilbit is comparable to

conventional crude in sediment

content

Levels are well below the limits

set by regulatory agencies and

the industry

Erosion of pipelines is simple to

detect and mitigate

No evidence of erosion has

been observed in dilbit pipelines

Summary: Dilbit is comparable to conventional crude in sediment content. No evidence of erosion has been observed in dilbit pipelines.

0

100

200

300

400

500

600

700

800

900

Sed

ime

nts

, pp

mw

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Concern #5: Viscosity of Dilbit Claim: Dilbit can be up to 70 times more viscous than conventional crude oil, resulting

in higher temperatures due to friction

Data and Analysis

Dilbit viscosities are

comparable to heavy sour

crudes

Crude tariffs specify a

maximum viscosity of 350 cSt

Dilbit viscosity that is accepted

for transportation supports

operating temperatures within

an acceptable range

Summary: The viscosity of dilbit is comparable to conventional heavy crudes and must meet pipeline specifications to be accepted for transportation.

0

20

40

60

80

100

120

140

160

180

Vis

cosi

ty a

t 2

0oC

, cSt

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Claim: The AB pipeline system has had ~16 times as many spills due to internal corrosion than the U.S. system, indicating that the dilbit is much more corrosive than the conventional oil that is primarily flowing through U.S. lines

Concern #6: Frequency of Pipeline Spills

Incident/Failure Case Failures/Year Failures per 1,000 Pipeline

Miles per Year

U.S. Crude Oil Pipeline Incident Historya

Corrosion - External 9.8 0.19

Corrosion - Internal 22.1 0.42

All Failures 89.3 1.70

Alberta Crude Oil Pipeline Incident Historyb

Corrosion - External 2.3 0.21

Corrosion - Internal 3.6 0.32

All Failures 22.0 1.97

aPHMSA includes spill incidents greater than 5 gallons. U.S. has 52,475 miles of crude oil pipelines in 2008.

bAlberta Energy and Utility Board Report. Alberta has 11,187 miles of crude oil pipelines in 2006.

Data and Analysis

US Statistics does

not report failures in

gathering pipelines

or spills that are

less than 5 gallons

In Alberta, all spills

are reported,

regardless of spill

volume and type of

pipeline

Summary: When corrected for spill volumes and pipeline types, the number of transmission pipeline failures in Alberta is comparable to the US (FEIS, 2011).

Spill Frequency of Comparable Pipeline Systems (FEIS, DOS, 2011)

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Concern #6: Frequency of Pipeline Spills (cont’d)

Gathering pipelines are different

• Gathering pipelines are typically smaller, operate at lower pressure to strength ratios and are not subject to same crude quality requirements as transmission pipelines are.

• Steel wet by oil does not corrode. Water separation is essential for internal corrosion to occur, this sometimes occurs in gathering lines due to higher water content and intermittent operation, but very rarely in transmission lines due to quality restrictions and constant flow.

• Due to these facts, gathering pipelines are generally much more susceptible to internal corrosion in comparison to transmission lines and are not statistically comparable.

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Summary: While there is insufficient information on the sediment composition in conventional crude and dilbit, there is no evidence to suggest that there is an increased risk of corrosion in dilbit pipelines.

Claim: An increased risk of internal corrosion may be related to the sediment composition of dilbits and specific sediment characteristics, including particle hardness and size distribution

Concern #7: Sediment Characteristics in Dilbit

Data and Analysis

The solids in conventional crude and dilbit are not well characterized

Most solids are fine at <44 microns, primarily of silica and iron.

Can precipitate out at low flow conditions

to form sludge

Sludge deposits are mixtures of

hydrocarbons, sand, clays, corrosion by-

products, biomass, salts, and water

No evidence that sludge formation would

occur in the presence of only fines

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Claim: A combination of chemical corrosion and physical abrasion can dramatically increase the rate of pipeline deterioration

Concern #8: Chemical Corrosion and Physical Abrasion

Data and Analysis

A combination of erosion and corrosion is improbable in dilbit

transmission line because it requires particle impact in a water

phase

If erosion were to be present, wall loss would be uniform and regular

mitigation strategies such as intelligent pigging and monitoring

technologies will catch this wall loss

Summary: Erosion-corrosion combination is improbable in dilbit transmission

pipelines.

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Claim: Dilbit pipelines operate at higher temperatures, which would significantly increase the corrosion rate which doubles with every 20 degree Fahrenheit increase in temperature

Concern #9: Operating Temperature of Dilbit Pipelines

Data and Analysis

Corrosion controlled by kinetics or diffusion can be

accelerated by an increase in temperature

Many other factors can affect the corrosion rate

positively or negatively: e.g. scale formation, limiting

reactant concentrations

Microbiologically induced corrosion (MIC) may be the

controlling mechanism underneath sludge deposits

Bacteria are most active between 10-40 C (50-

104 F); higher temperatures up to 70 C (158 F) may

reduce the corrosion rate

Summary: Dilbit transport will be within pipeline operating temperatures. Temperature increase does not necessarily lead to an increase in corrosion rate.

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Claim: Dilbit pipelines may be subject to a higher incidence of external stress corrosion cracking

Concern #10: External Stress Corrosion Cracking

Data and Analysis

No SCC failures reported for Fusion Bonded

Epoxy (FBE) coatings in over 40 years of

experience

A pipe is protected by external coatings and

cathodic protection (CP)

A Fusion Bonded Epoxy (FBE) coating is

permeable to CP current and the pipe will

remain protected even if the coating is

damaged Keystone XL pipeline segments

stockpiled in Gascoyne, ND, CBC

News, Nov 8, 2011

Summary: Current practice is to build pipelines with FBE coatings. Experience to date has shown that SCC is not likely on FBE coated pipelines.

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Conclusion

• In the context of pipeline transportation, characteristics of dilbit are not unique and are comparable to conventional crude oils

• Comparison of equivalent crude oil transportation systems shows no evidence that dilbit causes more failures or internal corrosion than conventional crudes

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John Zhou, Ph.D., P.Geol.

780-422-8853

John.zhou@albertainnovates.ca

www.albertainnovates.ca

Thank You!