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From Black to Gold:Nanotechnology in Upgrading of Heavy

Asphaltic Crude Oils

Murray R GrayDepartment of Chemical and Materials Engineering

University of Alberta

Edmonton, Canada

Society of Petroleum Engineers Distinguished Lecturer Programwww.spe.org/dl

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Outline

Heavy oil and its propertiesBenefits and challenges of upgrading heavy oilsNanotechnology – definition and significance for the petroleum industryDefinition of asphaltenes and their significanceMolecular compositionOpportunities for nanotechnologyIn situ upgrading technologies

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Heavy OilDense crude oil with APIo < 20Significant resources worldwideLower H, higher S, N and metals than light crudesHigh proportion of the barrel cannot be distilled, even under vacuum, circa 50% residuum

Wafra Field SteamfloodNeutral Zone

Chevron Joint Venture

Wafra – 14-18 oAPIHigh Sulfur

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Viscosity of Heavy Oil

Crude oil viscosity normally increases with density Bitumen with 9oAPI, 1,000,000 cP at 15oC1-methyl naphthalene: 9.8 oAPI, viscosity 2.6 cPMercury: APIo=-121 and viscosity 1.5 cP

Why?

Why is heavy oil viscous?

Viscosity of liquids is due to intermolecular forcesLarger molecules in heavy oil give more interactionAsphaltene fraction gives aggregates in the oil phase, size 5-20 nmOverlap of aggregates gives very high viscosity

7Rev. Inst. Fr. Petrole, 2004

Incentives for Upgrading of Heavy Oil

Transportation: Reduce viscosity to enable transport without adding a solvent (Canada, Venezuela) or heating pipeline (Alaska)Price: Increase the API gravity, reduce sulfur content

Refineries value high API crude oilsViscosity is not a significant issue for refineries

Example Upgrader Configurations

UpgraderProduction Pipeline Refinery

Diluent to reduce viscosity

Upgrading Economics

Complex expensive installationsCapex: $30K-$100K per (barrel/day) of throughput

Typical scale: 50-150 kBBL/DTotal cost circa $10 billion

Operating costs $5-$10/BBLSignificant loss of volume to byproducts

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Upgrading Yield and Quality

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Capital cost: Hydroconversion > Coking > Deasphalting

Canadian Light-Heavy DifferentialPar price – Hardisty Blend (US IEA)

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Iconic Image of Nanotechnology

Franks (1987) defined nanotechnology as “..technology where the dimensions and tolerances in the range 0.1 – 100 nm (from the size of an atom to the wavelength of light) play a critical role”

Ultrafine powders of nanoscale particlesNanoelectronics – “molecular electronics”, including both semiconductor, organic and hybrid systems

How does this relate to heavy oil?STM image of xenon atoms on Ni, Don Eigler, 28 Sep 1989

Profitable NanotechnologyCatalysts for making low-sulfur diesel and gasolineCo+Mo or Ni+Mo on alumina with high-pressure hydrogenFirst used in 1940’sSTM shows brim sites of high activity“BRIM” catalysts commercialized in 2004

Besenbacher et al., 2008

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Asphaltenes: Turning adversaries to allies

Most difficult fraction in heavy oilsSoluble in toluene, and insoluble in n-heptaneUnderstanding asphaltenes unlocks the value of bitumen/heavy oil resources (i.e. upgrading)Nanotechnology is the key

Understand, measure, and control behavior at length scale < 0.1 μm

Imaging of Individual Molecules

Gross et al., Science, 2009

Nakamura et al, Science, 2007

STM - Attach CO molecule to tip of probeTEM – Isolate molecule in a carbon nanotube

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Image of Nano-Aggregates of Asphaltenes

30 minute immersion of silicon wafer in dilute solution of asphaltene in tolueneAtomic force microscopy images courtesy JH Masliyah and Z Xu

1 μm

Hokusai, 1817“The Blind Men and the Elephant”

What do asphaltenes look like?

How are asphaltene molecules constructed?

Based on Sheremata et al., 2004; Strausz 1999

Bridged RingGroups

CondensedAlkyl Aromatics

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Pyrolysis apparatusInduction furnace

To vent or gas bag (GC)

Liquid N2

Curie point alloy strips coated with asphaltenes

Classes of products:Gas chromatography-mass spectrometry

Cold Lake C7 asphaltenes

(1 ring includes olefins) 21

AbundanceSmall BlocksBoiling < 538oC

Large BlocksBoiling > 538oC

One blockTwo blocks

Three blocksFour+ blocks

Asphaltenes built up from 1-10 large and small building blocks

# Rings 0 1 2 3

Paraffins n-C12 to n-C30

Cycloalkanes

Aromatics

Thiophenes

S S

S

Sulfides

S S S

4 5 6 7

S S

S S

23http://www.ldeo.columbia.edu/res/fac/micro/images.section/pages/velcro.html

Why do asphaltenes aggregate so strongly?

Asphaltenes = “Molecular velcro”Much more difficult to analyze than DNARange of functional groups interactKinetics may be important

Asphaltene Assembly

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Blue = Water and acid-base interactions Purple = Metal – base interactionsOrange = hydrophobic domain Green = aromatic stacking

Nanotechnology Opportunities

Design catalysts for large molecules in heavy oilAtomic level imaging + computer simulation + controlled synthesis of catalysts

Design dispersants to prevent aggregation of asphaltenes

Control molecular behavior during upgradingControl viscosity?

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In Situ Upgrading

Why not upgrade in situ to avoid capital expense?

Reduce viscosity – crack large moleculesReduce density – increase H content, reduce S & NSignificant reactions require temperatures > 300oC

Two approaches under development:Partial combustion to generate hydrogen in situCoke the oil in place

In Situ Combustion with Horizontal Wells (THAI Process)

Image from Petrobank Resources

THAI Heavy Oil Pilot

In situ Combustion PLUS Catalysis

Harness the CO from partial combustion:CO + H2O = H2 + CO2

Catalyst needed to combine the hydrogen with the oilTwo approaches:

CAPRI - Place catalyst around production well bore to make use of gases to hydrogenate oil:Inject nanoparticle catalysts (MoS2) into the formation

Catalysts require high temperature (>300oC), high PH2, long time (1 h)

Pack annulus around production tubing with catalyst

Flowing Nanocatalyst Particles

Zamani et al., 2010 – 44 cm sand pack with 200 nm particles

How to inject catalyst into flowing oil?

Image from Petrobank website

In Situ Combustion: Production Versus Upgrading

Interesting and challenging production technologyControl of processSensitive to reservoir heterogeneities Oxygen breakthrough?

Upgrading requires exposure of oil to high temperature

Tradeoff between using heat to mobilize oil versus upgradingHigh complexity of subsurface process

Shell In Situ Upgrading Process (IUP)

350-400oC

• Shell Canada tested technique at Peace River• Electrical heaters raise temperature to 380-430oC• Coke the heavy oil in situ, vaporizing the cracked products• Vapor collected in wells above the heaters

New Technology Magazine, June 2008

Pilot Test at Peace River, Canada

Pilot testing in Peace River on bitumenProject began in 2004, completed in 200829 wells for the field test

18 well for electric heaters,3 producing wells8 observation wells

Produced over 100,000 barrelsLight oil product – 30 to 49oAPI from 8-10oAPI bitumenRecovery 50% of OOIP

Only achieve 20% with steamProblems with unreacted bitumen in product wells

Prospects for Shell In Situ Upgrading Process

Benefits:Heat transfer is slow but predictableSignificant upgrading achieved

Disadvantages High energy input for high TSimulations suggest 8:1 output/input ratioNeed to run downhole heaters on cracked gases, not electricity

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Conclusions

Heavy oils are complex nanofluidsChemically complex asphaltenesNano-aggregation behavior of asphaltenes dominates phase behavior and processing

Example of catalysts for sulfur removal suggests a path forward

Combine modern tools for imaging and computationControl nanoscale behavior

Upgrading of heavy oils is advancing based on nano-science

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Acknowledgements

Centre for Oil Sands Innovation at the University of AlbertaColleagues: Jacob Masliyah, H Yarranton (U of C), Zhenghe XuKuangnan Qian and Howard Freund (ExxonMobil)Student Arash Karimi

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