UNCONVENTIONAL(?) MIDDLE CAMBRIAN PETROLEUM

SYSTEMS IN THE GEORGINA BASIN, AUSTRALIA

Chris Boreham1, Dianne Edwards1, Lisa Hall1, Tom Bernecker1,

Lidena Carr1, Junhong Chen1, Tegan Smith1, John Laurie1, Andrew

Stacey1, Jingqiang Tan2 and Brian Horsfield2

1Basin Resources Group, Energy Division,Geoscience Australia

2GFZ- German Research Centre for Geosciences, Potsdam, Germany

AAPG Hedberg Conference “Fundamental Controls on Petroleum Systems in Lower Paleozoic and Older Strata”, Beijing, 21-24 April 2013

ACKNOWLEDGMENTS Isotope and Organic Geochemistry Lab. Staff

OUTLINE OF TALK

• Introduction

• geology and samples

• ‘Unconventional’ Petroleum Systems

• OiI-oil and oil-source correlation

• Specific source inputs and depositional

environment

• Australian and Global analogues

• Shale Gas

• Conclusions

LOCATION MAP Wells sampled for oil stains and source rocks

Owen 3H MacIntyre 2H

LITHOSTRATIGRAPHY

E

W

basal Arthur Creek (hot’) shale

OIL STAINS & BITUMENS

strong oil stain

Owen-2, 1065.11 m

Thorntonia Limestone

(Hay River Fm)

spotty oil stain/bitumen

in vuggy porosity

Elkedra-2, 283.9 m

Hagen Member

weak oil stain

Elkerdra-2, 353.5 m

Hagen Member

OUTLINE OF TALK

• Introduction

• geology and samples

• ‘Unconventional’ Petroleum Systems

• OiI-oil and oil-source correlation

• Specific source inputs and depositional

environment

• Australian and Global analogues

• Shale Gas

• Conclusions

HYDROCARBON COMPOSITION

GC: HEAVY, UNALTERED OIL

waxy

n-C22+

n-C37

GC: HEAVY, ALTERED OIL

position of n-C37

unresolved

complex

mixture

(UCM)

GC: LIGHT, UNALTERED OIL

n-C19

waxy

n-C22+

GC: LIGHT, ALTERED OIL

unresolved complex mixture

(UCM)

position of n-C17

low MW

UCM

Owen-2, 1019.5m, Arthur Ck Fm, Middle Cambrian; Rm 0.56%

Reflected white light photomicrograph:

Rm 0.56% - Vitrinite-like organic matter (derived from

graptolites/chitinozoans), bituminite and lamalgininte in carbonate.

Owen-2, 1019.5m, Arthur Ck Fm, Middle Cambrian

Fluorescence-mode photomicrograph:

As previous showing yellow-orange fluorescing lamalginite, dull brown

fluorescing bituminite and nonfluorescing vitrinite-like organic matter

MacIntyre-1, 797.9m, Arthur Ck Fm, Middle Cambrian

Reflected white light photomicrograph:

Possible bitumen coke (Rm 1.86%) occurring within porosity of fossil

fragments of unknown affinity.

SOURCE ROCK MATURITY (Tmax) basal ‘hot shale’ of the Arthur Creek Formation

CHEMICAL MATURITY PARAMETERS MPR & MPI based on phenanthrene and methylphenanthrenes

oil window gas window

POTENTIAL SOURCE ROCKS

VRc* 0.71%

Rm# 0.56% # chitinozoans/

graptolites

VRc* 1.14%

Rbit 1.86%

*Jarvie et al., 1991; VRc = 0.018Tmax - 7.16

HIERARCHICAL CLUSTER ANALYSIS

Dendrogram

Cambrian

Petroleum

Systems

PS

PS

PS

Arthur Creek-Hagen (!) PS

Variables 13Carom

C19/C23T

C22/C21T

C24/C23T

C26/C25T

C24Tet/C23T

C28H/C30H

C29H/C30H

C30X/C30H

C31R/C30H

C35S/C34S

T/H

Rearr/Reg

%27

%28

%29

S/H

N-ALKANE-SPECIFIC CARBON ISOTOPES

(solid line for oil stains and dash line for source rocks)

Hagen (.) PS

Arthur Creek (!) PS

Thorntonia (!) PS

Elkedra-7A

Arthur Creek-

Hagen (!) PS

N-ALKANE-SPECIFIC CARBON ISOTOPES

(solid line for oil stains and dash line for source rocks)

OUTLINE OF TALK

• Introduction

• geology and samples

• ‘Unconventional’ Petroleum Systems

• OiI-oil and oil-source correlation

• Specific source inputs and depositional

environment

• Australian and Global analogues

• Shale Gas

• Conclusions

BIOMARKER SOURCE PARAMETERS tricyclic (C19-C26), tetracyclic (C24) and pentacyclic (C27-C35) terpanes

m/z 191

BIOMARKER SOURCE PARAMETERS tricyclic (C19-C26), tetracyclic (C24) and pentacyclic (C27-C35) terpanes

m/z 191

m/z 191

C30H

BIOMARKER SOURCE PARAMETERS tricyclic (C19-C26), tetracyclic (C24) and pentacyclic (C27-C35) terpanes

*Jarvie et al., 1991; VRc = 0.018Tmax - 7.16

VRc* 0.8% VRc* 1.41%

GLOEOCAPSOMORPHA PRISCA (G. PRISCA) ?

Canning Basin

Dodonea-1 oil

southern

Georgina Basin

GLOEOCAPSOMORPHA PRISCA (G. PRISCA)

ORDOVICIAN G. PRISCA SIGNATURE

CH3 CH3

n-C15

n-C15

n-C18

ORDOVICIAN G. PRISCA SIGNATURE

C15cy

C16cy

CAMBRIAN G. PRISCA-LIKE SIGNATURE

PHOTIC ZONE ANOXIA

C40 isorenieratane &

2,3,6-trimethylarylisoprenoids

H2S-photosynthetic bacteria:

photic zone anoxia

1

6

2

5

3

4

CH3

CH3

CH3 CH3

CH3 CH3

CH3

CH3

CH3

CH3

C16 2,3,6-

isorenieratane

DEPOSITIONAL ENVIRONMENT

Marine carbonate

DEPOSITIONAL MODEL

OUTLINE OF TALK

• Introduction

• geology and samples

• ‘Unconventional’ Petroleum Systems

• OiI-oil and oil-source correlation

• Source inputs and depositional

environment

• Australian and Global analogues

• Shale Gas

• Conclusions

southern

Georgina Basin

Amadeus Basin

Alice-1 oil

Arafura Basin

Arafura-1 oil stain

MIDDLE−LATE CAMBRIAN PETROLEUM SYSTEMS

Officer Basin

E. Cambrian

SOURCE CONTROLS: d13C

Hagen (.) PS

Arthur Creek (!) PS

Thorntonia (!) PS

www.scotese.com/mlcambcl.htm

MIDDLE−LATE CAMBRIAN PETROLEUM SYSTEMS

OUTLINE OF TALK

• Introduction

• geology and samples

• ‘Unconventional’ Petroleum Systems

• OiI-oil correlation

• Oil-source correlation

• Source inputs and depositional

environment

• Australian and Global analogues

• Shale Gas

• Conclusions

Technically Recoverable Prospective Resource in the Arthur Creek Formation

5 BBL of oil and 33 TCF of gas at “mean” (Ambrose et al., CABSIII, 2012)

SHALE GAS

PetroFrontier Press Release May 2012

max. 2,500 units (1 unit = 200 ppm methane equiv.)

WELLS SAMPLED FOR SHALE GAS

Owen 3H MacIntyre 2H Baldwin 2H

Owen-3H (early oil window): vertical section 1,180 m; HZ section ~ 1000 m

••Occasional pores bleeding dark brown crude oil (1,097.5 m)

•Bleeding dark brown to brownish black crude oil; faint petroliferous odour

(1,101 m)

•Bleeding oil; fair petroliferous odour ( 1,104.5m)

•Numerous pores bleeding oil (1,108m)

MacIntyre-2H (end oil-early gas window): high angle pilot hole to 930 m

TVD; HZ section ~ 1000 m

•Log porosity 3-12 %

•Highly resistive > 2000 ohms

•Sweet spot at 870 m with peak log porosity of 12 %

•Strong petroliferous odour

•Hydrocarbon shows of C1-C5 recorded in entire (including low porosity

sections) high angle pilot section

•Indicates vertical fractures throughout the zone

WELLS SAMPLED FOR SHALE GAS

PetroFrontier Press Release Sept’12

MacIntyre-2H: Arthur Creek Fm

Oil

sta

inin

g

basal Arthur Creek ‘hot’ shale

Dri

lled

de

pth

(m

)

1-D BURIAL HISTORY MODELLING PetroMod 2011 (4-component Georgina compositional kinetics from Tan et al. JMPG submitted)

MacIntyre-1 (-2H) Owen-2 (-3H)

Tra

ns

form

ati

on

rati

o

uplift/erosion:

Alice Springs Orogeny

~80% kerogen transformation

~20% kerogen transformation

late oil-early gas window

early oil window

present-day

geothermal gradient

49oC/km

present-day

geothermal gradient

29oC/km

max. 2,500 units (1 unit = 200 ppm methane equiv.)

GOR-Isotope Ver 2.2.8

MacIntyre-2H

Tmax 462oC; VRc* 1.14%

MacIntyre-2H

Tmax 462oC ; VRc* 1.14%

Owen-3H

Tmax 436oC; VRc* 0.71%

*Jarvie et al., 1991

Rc = 0.018Tmax - 7.16

C-isotopes C1-C3 gases

-50

-48

-46

-44

-42

-40

-38

-36

-34

-32

-30

-28

methane ethane propane i-butane n-butane i-pentane n-pentane

carb

on

iso

top

es (

‰)

MacIntyre-2H 1056m

MacIntyre-2H 1070m

MacIntyre-2H 1200m

MacIntyre-2H 1259.5m

MacIntyre-2H 1400m

MacIntyre-2H 1415m

MacIntyre-2H 1600m

MacIntyre-2H 1645m

MacIntyre-2H 1803m

Owen-3H 1072.5m

Owen-3H 1097.5m

Owen-3H 1300m

Mud Gas: MacIntyre-2H 20–423 units meq

Owen-3H 9–23 units meq

(1 unit meq = 200 ppm)

20 units

error ±0.6‰ (2σ)

15

9

23

Up to

423 units

Shale (mud) gas: carbon isotopes

Owen-3H

•Wide range in C-isotopes of wet gases

•Multiple ‘sources’ for gas (early mature)

MacIntyre-2H

•Wet gases isotopically uniform

•Limited ‘sources’ for gas (late mature)

•Methane loss - isotopic fractionation

CONCLUSIONS

•Georgina source rocks contains organic matter derived from marine

algae and bacteria with minor G. prisca-like inputs

•Georgina Basin is a local expression of a Middle−Late Cambrian

oceanic anoxic event (OAE) that lead to deposition of organic-rich

‘black shales’ on a global scale;

•Three main (unconventional?) petroleum (oil) systems identified in the

Georgina Basin

•early Middle Cambrian Thorntonia (!) PS

•anoxic platform facies

•late Middle Cambrian Arthur Creek (!) PS

•euxinic, deeper water, outer ramp facies

•early Late Cambrian Hagen (.) PS;

•anoxic, evaporitic sabkha facies

•Biodegradation of oil is a major risk (shallow depth < 1000 m);

•1st Australian shale gas isotopic characterisation.

3 Questions

•Where’s a good robust maturity parameter for ‘old’

OM?

•no ‘silver bullet’, use many + burial history model

•Is there a place for a continuous PS: unconventional

to ‘hybrid’ to conventional, or am I just confused with

terminology?

•definition: need mechanical stimulation for production

•internal stratigraphy of ‘shale’

•If an oil is biodegraded can it also be unconventional

(e.g. oil-wet shale with nD permeability)?