Geochemical Methods and Assessment of Oil Shales · 2012-05-18 · Trinidad Venezuela Argentina Kuwait Libya Oman Saudi Arabia United Arab Emirates Iraq Australia India Malaysia Thailand

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Geochemical Methods and Assessment of Oil Shales

Tim Ruble

Senior Geochemist

[email protected]

Presentation Outline

• Source Rock Analyzer (SRA)• Fischer Assay (FA)• Hydrous Pyrolysis (HP)• In Situ Simulator (ISS)• Chemical Considerations• Geologic Considerations• Analytical Program Recommendations

A wide range of technologies are available for oil shale utilization. Generation of liquid hydrocarbons (and gas) by retorting is the most common approach discussed for western US oil shale utilization.

How will oil shale be utilized?

• What resources are amenable to mining & surface retorting?

• How will in situapproaches be applied to different deposits?

• How do environmental impacts differ when different approaches are applied to a specific location?Office of Naval Petroleum and Oil Shale

Reserves, U.S. Department of Energy

Retorting conditions will determine the yield and quality of products generated from oil shale.(Slide Courtesy of Justin Birdwell, 2011)

Technically recoverable resources

Define resources:Retort-generated hydrocarbon liquids and gas

Methods for estimating Recovery Factors are needed for oil and gas products, with compositional estimates based on laboratory and pilot scale tests.

This is needed for representative technologies that are expected to be implemented.

(Slide Courtesy of Justin Birdwell, 2011)

Source Rock Analyzer

Pyrolysis Methods – Source Rock Analyzer

• Pyrolysis is the heating of organic matter in the absence of oxygen to yield organic compounds (Peters, 1986).

• Programmed Pyrolysis:– Pulverized samples are

gradually heated under an inert atmosphere

– Heating distills the free organic compounds (bitumen), then cracks pyrolytic products from the insoluble organic matter (kerogen)

Pyrolysis

Pyrolysis Methods – Source Rock Analyzer

Pyrolysis instrument that uses an FID detector and IR cells to measure:

vHydrocarbon Content – S1

vRemaining Hydrocarbon Generation Potential – S2

vOrganic richness – TOC

vThermal Maturity – Tmax

Rapid screening method

Source Rock Analyzer (SRA)

Pros:• Rapid (~40 min)• Small Sample Size (~100 mg)• Commercially Available• Cost Effective (~$90/per sample)• Can be used for bulk Kinetics**

Cons:• No Hydrocarbon Compositions**• Generation and Mass Transport

Mechanisms Differ from Oil Shale Processes

Fisher Assay

Retort

Condenser

Vent to hood/scrubber

Cooling bath

Oven or heating mantle

Cooling water inlet Oil and vapor

ASTM standard method for determining oil yield potential of oil shale

Collected oil

Collected water

100 g of shale is heated to 500°C at 12°C/min (20 min heat-up) and held for 40 min at atmospheric pressure

Oil, water and residual oil shale are collected

No gases are recovered (gas yield estimated)

Oil product yield and composition is comparable to surface retorting methods

Condensed Oil

Cooling water outlet

Mimics surface oil shale retorting

Pyrolysis Methods – Fischer Assay


SRA vs. Fisher Assay

y = 15.536x - 33.756R2 = 0.9462

0

50

100

150

200

250

0 2 4 6 8 10 12 14 16

Fischer Assay Yields (wt.% oil)

SR A

naly

zer

Pyro

lysi

s (S

2) Y

ield

s (m

g H

C/g

R)

Pyrolysis Methods – Fischer Assay

Pros:• Fairly Rapid (~2 hr)• Moderate Sample Size (~100 g)• Commercially Available• Cost Effective (~$125/per sample)• Products for Compositional Analysis• Mimics Surface Oil Shale Retort

Cons:• No Kinetics**• Generation and Mass Transport

Mechanisms Differ from In Situ Oil Shale Processes

Hydrous Pyrolysis

20°C360°C

20°C

Generated Gases

Expelled OilSource

Rock200 g

Water400 g

He(25 psia)

Spent Rock

72 h

Mimics petroleum generation in nature

PreparationPyrolysis

Cool-down &Collection

Heat-up

Pyrolysis Methods – Hydrous Pyrolysis



Rock

Water

Expelled Oilphysically, chemically, and isotopically similar to natural crude oils

Quartz Reactor

Line

before after 330 C/72 h

Rock

Water

Lewan et al., 1979(Slide Courtesy of Michael Lewan, 2011)


(Lewan, 1985)

Pros:• Products for Compositional Analysis• Mimics Natural Oil Generation• Bulk and Compositional Kinetics

Cons:• Time Consuming (days-weeks)• Large Sample Size (~200-500 g)• Limited Commercial Availability• Generation and Mass Transport

Mechanisms Differ from Oil Shale Processes**

In Situ Simulator

500-mL Parr reactor

250-mL Parr reactor

Helium purged and evacuatedP0 < 0.6 psia

Preparation

~20°C <5°CValves closed

Electric heaterΔT/ Δ t = 3°C/min

Coolant bath

Pressure tested and purged with He (1000 psia) then evacuatedP0 <0.6 psia

100-g oil shale

Mimics in situ oil shale retorting

Pyrolysis Methods – In Situ Simulator


Pyrolysis

Sample is heated to the desired temperature and held for between 6 and 288 hours

500 < P0 < 800 psiaP0 < 0.6 psia

0

200

400

600

800

1000

0 100 200 300

Reac

tor p

ress

ure

(psi

g)

Pyrolysis time (hrs)

360°C <5°CValves closed

Oil vapor and Gas



Collection

After the desired pyrolysis time has passed, the reactor is vented to the collector (complete in <1 min).

P < 200 psig P < 200 psig

~15°C360°CValves open

Oil vapor and Gas



Cool-down

Both the reactor and collector are brought to room temperature (~24 hours) prior to recovery of spent shale and products.

6 < P < 17 psia 45 < P < 85 psia

~20°CValves closed

~20°C

Gas

Condensed Oil

Spent shale



Gas

Condensed Oil


Pros:• Moderate Sample Size (~100 g)• Products for Compositional Analysis• Mimics In Situ Oil Shale Retorting• Bulk and Compositional Kinetics**

Cons:• Time Consuming (days-weeks)• Limited Commercial Availability• Generation and Mass Transport

Mechanisms may Differ from some Oil Shale Processes**

(Justin Birdwell, 2011)

Chemical Considerations

KerogenInsoluble organic solid

BitumenSoluble organic tar

Crude OilHydrocarbon-rich

liquid

Natural GasHydrocarbon-rich gas

Char/PyrobitumenInsoluble organic solid

ImmatureMature

Over mature

Hydrocarbon Generation

Hydrogen SulfideNon-hydrocarbon-rich gas

1

2

3

4

5

6

7

8

9

Reactions & Processes

(Lewan, 2011)(Slide Courtesy of Michael Lewan, 2011)

Bitumen* Expelled Oil*0 6 12 0 2 4 0 1 2 3

Unheated

300oC/72h

Kerogen*

320oC/72h

330oC/72h

340oC/72h

345oC/72h

350oC/72h

355oC/72h

360oC/72h

365oC/808h

Kerogen

Oil

Bitumen

*wt% of Rock (Lewan, 1985)

Fundamentals of Oil Formation

(Slide Courtesy of Michael Lewan, 2011)

HP-Expelled Oil

HP-Bitumen

Rock-Eval S2 at 475 to 600ºC

Pyrolysis Product Compositions

Behar et al.(1997)

AA

RE

Dry Squeezing(Lafargue et al., 1989)

(Lewan, 2011)

(Slide Courtesy of Michael Lewan, 2011)

Fischer Assay, 500°C, 1 h; API = 23.0°

In-situ Simulator, 360°C, 120 h; API = 50.0°

FID

Resp

onse

C35Tb = 488°C

C20

C11

CS2C17

C10

Naphtha

UCM

C20Tb = 340°C

Kerosene Diesel Resid

Naphtha Kerosene Diesel Resid

Volatiles (<C15) 60.7Saturates 25.4Aromatics 6.6Resins 5.9Asphaltenes 1.4

Elemental RatiosH/C = 1.85, N/C = 0.013, O/C = 0.006

FID

Resp

onse

Volatiles (<C15) 9.5Saturates 35.3Aromatics 22.2Resins 29.1Asphaltenes 3.9

Elemental RatiosH/C = 1.61, N/C = 0.023, O/C = 0.014

Yield = 65 wt.% of Fischer Assay

18

Effects of pyrolysis conditions on shale oil


Results – Oil yields & specific gravities

Fischer Assay has the highest oil yield. Hydrous Pyrolysis and ISSyields were ~70% and ~30% of Fischer Assay, respectively.

In Situ Simulator generated the lightest oil, and Fischer Assay produced the heaviest. Differences between shales were minimal.

TOC = 19.3 wt%

10.0 wt% 29.7 wt%

0

200

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1200

Piceance Mahogany

Garden Gulch Member

Uinta Mahogany

Oil

yiel

d (m

g-oi

l/g-

TOC)

Fischer Assay Hydrous Pyrolysis In Situ Simulator

0.65

0.7

0.75

0.8

0.85

0.9

0.95

Piceance Mahogany

Garden Gulch Member

Uinta Mahogany

Oil

spec

ific

grav

ity

Fischer Assay Hydrous Pyrolysis In Situ Simulator


Results – Whole oil GC-FID

Piceance Mahogany Garden GulchUinta Mahogany

Hydrous Pyrolysis

In Situ Simulator

Fischer Assay

Naphtha<C9 Kerosene

C9 – C14

DieselC15 – C20

Resid>C20

C35Tb = 488°C

C20Tb = 340°C


Geologic Considerations

Lake Uinta Source-Rock Lithofacies

Birgenheier & Vanden Berg (2011)

Saline Facies


Offshore Open Lacustrine Facies


Nearshore Open Lacustrine Facies


Why Recognizing Oil Shale Facies is Important

Saline Lacustrine Oil ShaleSaline Lacustrine Oil Shale

Offshore Open Lacustrine Oil ShaleOffshore Open Lacustrine Oil Shale

NearshoreNearshore Open Lacustrine Oil ShaleOpen Lacustrine Oil Shale

PaludalPaludal CoalCoal

Immiscible Oil Rock Extract

Sat. TIC

1520

25

30

Ph 22

26SatAro

P SatAroP

A

g-cerane


Sat. TIC

1520

25

30

Ph 22

26SatAro

P SatAroP Sat

AroPA Sat

AroPA

g-ceraneg-cerane


Sat. TIC

Pr

20

25

30

Ph

PrC30 H

15 SatAroP Sat

AroPA

g-cerane


Sat. TIC

Pr

20

25

30

Ph

PrC30 H

15 SatAroP

SatAroP Sat

AroPA Sat

AroPA

g-ceraneg-cerane


Sat. TIC

1520 25

30

15 2025

30SatAro

P SatAroP

A


Sat. TIC

1520 25

30

15 2025

30SatAro

P SatAroP

A

Sat. TIC

1520 25

30

15 2025

30SatAro

PSatAro

P SatAroP

A SatAroP

A


Sat. TIC

15 20

25

30

Pr

2025 30

SatAroP Sat

AroP

A


Sat. TIC

15 20

25

30

Pr

2025 30

SatAroP SatAroP Sat

AroP

A SatAro

PA

3.2% TOC792 HI

515 bbl/a-ft*

Oil generated is moderately waxy and often has a high sulfur content.

5.9% TOC734 HI11.6 gal/ton371 bbl/a-ft*

Oil generated is a highly colored solid wax at room temperatures.

67.7% TOC586 HI

1129 bbl/a-ft*

Oil generated has a high wax content, but also contains a high proportion of aromatics.


Oil generated is free -with relatively low wax content.

*Immiscible oils generated during hydrous pyrolysis at 345oC/72h or at a transformation ratio of ~75%.


Sat. TIC

1520

25

30

Ph 22

26SatAro

P SatAroP

A

g-cerane


Sat. TIC

1520

25

30

Ph 22

26SatAro

P SatAroP Sat

AroPA Sat

AroPA

g-ceraneg-cerane


Sat. TIC

Pr

20

25

30

Ph

PrC30 H

15 SatAroP Sat

AroPA

g-cerane


Sat. TIC

Pr

20

25

30

Ph

PrC30 H

15 SatAroP

SatAroP Sat

AroPA Sat

AroPA

g-ceraneg-cerane


Sat. TIC

1520 25

30

15 2025

30SatAro

P SatAroP

A


Sat. TIC

1520 25

30

15 2025

30SatAro

P SatAroP

A

Sat. TIC

1520 25

30

15 2025

30SatAro

PSatAro

P SatAroP

A SatAroP

A


Sat. TIC

15 20

25

30

Pr

2025 30

SatAroP Sat

AroP

A


Sat. TIC

15 20

25

30

Pr

2025 30

SatAroP SatAroP Sat

AroP

A SatAro

PA

3.2% TOC792 HI

515 bbl/a-ft*

Oil generated is moderately waxy and often has a high sulfur content.


Oil generated is a highly paraffinic redish colored solid wax at room temperatures.

67.7% TOC586 HI

1129 bbl/a-ft*

Oil generated has a high wax content, but also contains a high proportion of aromatics.


Oil generated is free-flowing, black liquidwith relatively low wax content.

*Immiscible oils generated during hydrous pyrolysis at 345oC/72h or at a transformation ratio of ~75%.

C 10-40 ALKANE YIELDSHydrous Pyrolysis

0

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300

0 20 40 60 80 100

Transformation Ratio %

bbl/a

-ft

HYDROCARBON YIELDSRock-Eval Pyrolysis

0

500

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2500

0 20 40 60 80 100


bbl/a

-ft

HYDROCARBON YIELDSHydrous Pyrolysis

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bbl/a

-ft

SATURATES YIELDSHydrous Pyrolysis

0

200

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600

800

1000

1200

0 20 40 60 80 100


bbl/a

-ft

Offshore 2.5× Nearshore

Offshore 2× Nearshore

Offshore = Nearshore

C 10-40 ALKANE YIELDSHydrous Pyrolysis

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Importance of Organic Facies

Conventional method to grade oil shale is the modified Fischer Assay.

►Although this method is useful for measuring bulk oil yields duringlaboratory and/or surface retort, it operates within a much higher thermalregime, up to 500-600°C, compared to modern in-situ conversion methodsconducted at maximum temperatures of only ~370°C. As aresult, modified Fischer Assay yields and product composition are notequivalent.

►No standard grade is used to define oil shale resources. Someestimates use a minimum Fischer Assay yield of 15 gal/ton, while othersuse 10 gal/ton.

Hydrous Pyrolysis data show: Medium grade Offshore Facies ( 28 gal/ton Fischer assay)Low grade Nearshore Facies ( 12 gal/ton Fischer assay)Can generate comparable paraffin yields!!

Analytical Program Recommendations

Screening:• Source Rock Analyzer• Rock-Eval

Evaluation:• Fischer Assay• In Situ Simulator• Hydrous Pyrolysis

• Others (eg. TGA/Py-GC)

Up Scale Evaluation:• Pilot Plant Scale Simulations

Oil Shale Evaluation Services

• Fischer Assay• Source Rock Analyzer• Wellsite Geosciences

—Geochemistry—Mineralogy—Elemental Composition

• Wellsite Handling / Preservation / Gamma• Shale Rock Properties (SRP)• Shale Fabric Analysis• CT Scanning of Whole Core

Acknowledgements

Michael D. Lewan – U.S. Geological Survey

Justin E. Birdwell – U.S. Geological Survey

R. Paul Philp – University of Oklahoma

Questions?

Documents

Geochemical Methods and Assessment of Oil Shales · 2012-05-18 · Trinidad Venezuela Argentina Kuwait Libya Oman Saudi Arabia United Arab Emirates Iraq Australia India Malaysia Thailand