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40 LABORATORYLOCATIONS IN21 COUNTRIES

NORTH AMERICACa n a d aUn i t e d S t a t e s

EUROPENo r wa yUn i t e d K i n g d o mKa z a k h s t a n

LATIN AMERICABr a z i lM e x i c oTr i n i d a dVe n e z u e l a

MIDDLE EAST / NORTH AFRICAKu w a i tL i b y aO m a nSa u d i A r a b i aUn i t e d A r a b Em i r a t e sI r a q

ASIA PACIFICAu s t r a l i aI n d i aM a l a ys i aT h a i l a n dNe w Z e a l a n dI n d o n e s i a

Source Rock Geochemistry and Thermal Maturity Discussion of the Utica-Point Pleasant in the Northern Appalachian Basin

Presented by: Dick Drozd

Email: [email protected]

© 2009 Weatherford Laboratories. All rights reserved.

Presentation Outline

• What are the important elements of a geochemical evaluation and why.

• Specific geochemical issues with the Ordovician section.

• Geochemistry of the Utica – Point Pleasant and equivalent units.

• Implications for exploration.

• Questions


Significant Elements of Source Rock Evaluation

1. Organic Richness

2. Remaining Potential for Generation

3. Thermal Maturity

4. Kerogen Type

• All measurements are made on present-day as-received material

• Original condition most significant for exploration


Total Organic Carbon (TOC)

• Solid organic material contained within a sample that can be subdivided into kerogen and bitumen.

• Total organic carbon determined by combustion of samples that have been treated with acid to remove inorganic carbon.

• Usually reported in units of weight fraction, TOC weight divided by sample weight.


Why is TOC Important?

• TOC provides the carbon for hydrocarbons

• TOC provides increased porosity with increasing thermal maturation

• TOC provides adsorptive sites for hydrocarbons

– To retain oil for cracking to gas

– Storage of adsorbed gas

LOG 1: ORGANIC RICHNESS

5540

5560

5580

5600

5620

5640

5660

5680

5700

5720

5740

0.0 5.0 10.0TO C (wt.%)

DE

PT

H (

feet

)

OrganicRich


Total Organic Carbon Guidelines

Present day organic richness of source rock

Quality TOC (wt%)

Poor <0.5

Fair 0.5 to 1

Good 1 to 2

Very good 2 to 4

Excellent >4

Threshold Shale Gas

Threshold Shale Oil

The TOC Myth: “If I have high TOC, I have a good source rock.” (Dembicki, 2009)


Programmed Pyrolysis

Pyrolysis• A chemical degradation reaction that is caused by thermal

energy. (The term pyrolysis generally refers to an inert environment.)

Temperature-Programmed Pyrolysis• A pyrolysis during which the sample is heated at a controlled

rate within a temperature range in which pyrolysis occurs.


Source Rock Analyzer (SRA)

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

• Available Hydrocarbon Content – S1

• Remaining HydrocarbonGeneration Potential – S2

• Organic Richness – TOC

• Thermal Maturity – Tmax


Parameters Measured

• With Flame Ionization Detector (FID) - detects hydrocarbons only:

– Volatile hydrocarbon content – S1

– Pyrolized hydrocarbons – S2

• Tmax – Temperature of maximum S2 release

• With Infrared Detector – detects CO and CO2 only:

– CO2 generated during pyrolysis – S3

– Total organic carbon (TOC) – S4


Displayed Pyrogram

600oC

S1

S2

Tmax

Temperature trace (nonisothermalat 25oC/min)

300oC

Time (mins.)

Yield

S4

S3

Volatile Hydrocarbon

Content

Remaining Generative PotentialHydrogen

CO2 Generation

Measure of TOC

© 2009 Weatherford Laboratories. All rights reserved.11

Challenging to Measure

Maturation parameters are indicative of the maximum paleo-temperature that a source rock has reached:

• Visual– Vitrinite reflectance (whole rock or kerogen concentrate)

– Color indices (Conodonts, Zooclasts, bitumen)

• Chemical– Programmed Pyrolysis Tmax (chemical)

Thermal Maturity


Vitrinite Reflectance

• Vitrinite: a term (from coal petrography) for the jellified remains of higher plant tissues (post-Silurian)

• With increasing thermal alteration, vitrinite becomes more graphitic (condensed aromatic rings increase) and reflects more light

• Reflectance (%Ro) tracks kerogen maturity• Other maturity measures expressed on vitrinite “scale”


Problems Obtaining Ro Maturities

• Properly identified vitrinite:– Primary

– Recycled

– Cavings

– Mud additives

• Factors affecting accurate Ro measurements:

– Poor polish

– Oxidized vitrinite

– Inclusions (pyrite, bitumen, other macerals)

• Poor statistics (too few particles)

Hunt, 1996, p. 515


Calculated %Ro Values from Tmax

Calculated values

Jarvie et al., 2001

%VRo from Tmax = (0.0180 x Tmax) -7.16


Issues with Tmax

• Anything that affects the peak shape will affect Tmax– Contamination from drilling mud may alter the S2 peak,

– with high amounts of indigenous or migrated oil present, the oil part of S2 may exceed the kerogen S2 and Tmax will be too low,

– at very high maturities, there is no S2 peak (flat) and Tmax is virtually random

– dependent on kerogen type.


Some S2 Pyrograms

Tmax Tmax?

© 2009 Weatherford Laboratories. All rights reserved.17

Vitrinite Reflectance (% Ro) scale for maturity assessment • Immature <0.6% Ro• Oil window 0.6-1.1% Ro• Wet gas window 1.1-1.4% Ro• Dry gas generation 1.4-~2.2% Ro• Dry gas preservation ~2.2-~3.2% Ro• Gas destruction >~3.2% Ro (?)

Thermal Maturity Guidelines


The TOC Myth: “If I have high TOC, I have a good source rock.” (Dembicki, 2009)

• Although a good source rock must have high TOC, not all organic matter is created equal.

• The more hydrogen associatedwith the carbon, the morehydrocarbon it can generate –particularly liquid hydrocarbons.

• Thus, we also need an indicator for the amount of hydrogen present in the organic matter (measured present day – projected into the past).

KEROGEN TYPE

From, Dembicki, H. (2009), Three common source rock evaluation errors made by geologists during prospect or play appraisals, AAPG Bulletin, v. 93, p. 341 - 356


8%

18%

54%

20%

25%

29%

30%

16%

Type III (HI=250)

12%

23%

46%

19%

Type II (HI=420)

Primary Hydrocarbon Generation Yields

Type I (HI=810)

Jarvie, unpublished data

C1

C2-C4C5-C14C15+

Oil vs. Gas

(Not secondary cracked products)


• Maceral composition is determined via petrographic (optical) analyses of pelletized samples or thin sections.

• Three Primary Maceral Groups.– Liptinite: Hydrogen-Rich

– Vitrinite: Oxygen-Rich

– Inertinite: Carbon-Rich

• Numerous macerals and sub-macerals in each maceral group.

• Fully characterize Kerogen Type via Maceral Composition and Programmed Pyrolysis.

Maceral Group

MaceralsOrganic

PrecursorsKerogen

Type

Liptinite

Alginite I Fresh Water Algae I

Alginite II Marine Algae II

ExiniteSpores

(Sporinite), Pollen

II

Cutinite Leaf Cuticle II

Resinite Resin,Tree Sap II

Vitrinite Vitrinite,Psuedovitrinite Woody Tissue III

InertiniteSemifusinite,

Fusinite, Sclerotonite, etc.

Reworked and/or

Oxidized Material, Charcoal

IV

Kerogen Maceral Types


Visual Kerogen Type Assessment

Amorphous organic matter

Type I: (oil prone)lacustrine algae

Type II: (oil prone)marine algae


Structured organic matter

Type III: (gas prone)woody

Visual Kerogen Type Assessment


0

10

20

30

40

50

60

0 2 4 6 8 10 12 14 16

TOC (wt.%)

Rem

ain

ing

Gen

erat

ion

Po

ten

tial

(S

2)

Original

Type I Type II

MixedType II-III

Type III

Type IV

ca. 0.55% VRo

Kerogen Quality Plot –Barnett Shale Example

0

10

20

30

40

50

60

0 2 4 6 8 10 12 14 16

TOC (wt.%)

Rem

ain

ing

Gen

erat

ion

Po

ten

tial

(S

2)

25% Converted

Type I Type II

MixedType II-III

Type III

Type IV

ca. 0.70% VRo

0.00

10.00

20.00

30.00

40.00

50.00

60.00

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00

TOC (wt.%)

Rem

ain

ing

Gen

erat

ion

Po

ten

tial

(S

2)

50% Converted

Type I Type II

MixedType II-III

Type III

Type IV

ca. 0.85% VRo

0.00

10.00

20.00

30.00

40.00

50.00

60.00

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00

TOC (wt.%)

Rem

ain

ing

Gen

erat

ion

Po

ten

tial

(S

2)

75% Converted

Type I Type II

MixedType II-III

Type III

Type IV

ca. 1.00% VRo

0.00

10.00

20.00

30.00

40.00

50.00

60.00

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00

TOC (wt.%)

Rem

ain

ing

Gen

erat

ion

Po

ten

tial

(S

2)

90%+ Converted

Type I Type II

MixedType II-III

Type III

Type IV

ca. 1.50% VRo

0

10

20

30

40

50

60

0 2 4 6 8 10 12 14 16

TOC (wt.%)

Re

ma

inin

g G

en

era

tio

n P

ote

nti

al

(S2

)

Original

25% Converted

50% Converted

75% Converted

90%+ Converted

Type I Type II

MixedType II-III

Type III

Type IV

25% 0.70%Ro

50% 0.85%Ro

75% 1.00%Ro

90% 1.50%Ro

Samples as measured today, at present maturity!


Measured present day:• TOC

• Volatile Hydrocarbons

• Remaining Potential

• Kerogen Type

• Thermal Maturity

• “Magic” is a set of calculations described in the literature but too long for this presentation.

• Yield a set of yield estimates.

Estimation of Yields

Original:• TOCo• Total Potential• Kerogen Type• Partitioning gas/oil

MAGIC

Measured Oil

Estimated Oil

Cracked Gas

0

50

100

150

200

250

300

350

Utica ShaleCollingwood

Shale Barnett Shale Gas

Measured Oil Estimated Oil Cracked Gas

3500

2500

2000

1500

1000

500

Gas

(Mcf

/a-f

t)

Oil

(bb

l/a-f

t)

3000

Barnett Shale (Oil)


Early Paleozoic age, therefore no primary Type IIIorganic matter present

• Maturity - no vitrinite – Substitute: – Zooclasts reflectance (chitinozoans, scolecodonts, etc.) or bitumen

reflectance

– Conodont color

• Original Kerogen Type – Original hydrogen index (HIo)– Primary organic matter marine

– Contribution from reworked/ recycled organic matter likely low,

– Contribution of oxidized organic matter unknown

– Over large geographic area & depositional settings variations likely (measured HIo 200 to 650)

Utica / Point Pleasant & Equiv. Rocks


Stratigraphy


Utica & Point Pleasant Thickness


Structure on Top of the Trenton


Source Rock Maturation Status


• Utica Undifferentiated• Point Pleasant• Collingwood• Cobum• Antes• Cobourg• Lindsay

Point Pleasant Equivalents


Two papers in the 1990’s Cole et al and Drozd & Cole examined the petroleum systems in Ohio. Conclusions:

• Oil in Ohio classified into three families– Group 1 found in Cambrian, Ordovician and some Silurian reservoirs,

fingerprint characteristics of Early Paleozoic organic matter, and heavy carbon isotopes,

– Group 2 found in some Silurian and Devonian to Pennsylvanian reservoirs, variable but distinct fingerprint characteristics, and intermediate carbon isotopes,

– Group 3 found in a few Berea reservoirs similar to Group 2 in fingerprint pattern, but with light carbon isotopic composition.

• Source-Oil Correlation– Group 1 oils from Point Pleasant Shale,

– Group 2 oils from facies of Ohio Shale, hence variable characteristics,

– Group 3 oils from Sunbury Shale.

Source Rock – Oil Correlation


Contour Map – TOCoUtica / Pt Pleasant


Contour Map – RoEquiv Pt Pleasant


Contour Map – NOC


Comparison of Pt Pleasant to Other Shale Plays

TOC (wt%)

TOCo (wt%)

Maturity (%Ro eq)

Ohio Pt Pleasant 1.65 2.01 0.84

Attractive 2.40 2.80 0.76

Michigan Collingwood 1.96 2.74 1.44

Ontario Lindsay 5.20 5.52 0.69




Ohio Utica 1.00 1.25 0.85

PA Utica 1.76 2+

Barnett (Oil) 3.86 0.74

Eagle Ford (Oil) 2.76 0.98

Geneseo/Burkett 2.52 1.19

There is some variability in TOC in OH, similar to Collingwood in MI.Average maturity very different.

“Selected” samples can have much higher TOC than cuttings.

Utica in PA may include Pt Pleasant facies; much more mature.

Other shale oil plays.


• Our understanding of the kinetic of the Point Pleasant kerogen is very limited due in part of lack of appropriate samples (low maturity but similar facies to producing area)

• Therefore, maturity guides may not be as appropriate as we would like.

Ongoing Thoughts


Kerogen Type DeterminesTiming/Rates of Conversion

0.60 430

440

450

460

470

480

4200.40

0.75

0.95

1.10

1.30

1.50

%Ro Tmax (oC)

Type II

Type II-OS

Type III Type I


• Our understanding of the kinetic of the Point Pleasant kerogen is very limited due in part of lack of appropriate samples (low maturity but similar facies to producing area)

• Therefore, maturity guides may not be as appropriate as we would like.

• Product expectation (heavier oil, light oil, condensate, wet gas) is also less certain than preferred.

• Variation in properties across a play is always an issue when the play is new, because we have yet to fully measure parameters needed to obtain a basic understanding of the detailed rock characteristics.

Ongoing Thoughts


The first step in our successful development of the Eagle Ford Shale

play was to “prove the rocks”.

(Richard Stoneburner, COO, Petrohawk Energy)


Questions?