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Geochemistry of Dew Point Petroleum Systems, Browse Basin, Australia
D.S. Edwards1, E. Grosjean1, T. Palu1, N. Rollet1, L. Hall1, C.J. Boreham1, A. Zumberge2, J. Zumberge2, A.P. Murray3,
P. Palatty1, N. Jinasdasa1, K. Khider1 and T. Buckler1 1Geoscience Australia, Canberra
2GeoMark Research Ltd, Houston 3Murray & Partners, Perth
AOGC Fremantle 3-5 December 2016
Browse Basin Hydrocarbon Distribution
AOGC Fremantle, 2016
Le Poidevin et al., 2015, Australian Petroleum Accumulations Report 7 Browse Basin, Record 82545
Project Aim, Workflows & Results • High-grade areas with
increased (liquids-prone) prospectivity, specifically within gazetted acreage
• New geochemical analyses; Constructing a petroleum systems model
• Identified 4 dew-point petroleum systems
2016 Acreage Release http://www.petroleum-acreage.gov.au/
AOGC Fremantle, 2016
Westralian 1 Early – Middle Jurassic gas Plover–Plover Fm
Extent of Mesozoic Petroleum Systems
AOGC Fremantle, 2016
Rollet et al., 2016, A regional assessment of CO2 storage potential in the Browse Basin, Record.2016.017
Westralian 2/3 Caswell Jurassic-Cretaceous wet gas Vulcan Fm–Brewster Mbr
Westralian 1 + 2 Heywood Jurassic oil & gas Plover/Vulcan coals–Nome
Heywood Graben
Westralian 3 + 1 &/or 3+2 E Cretaceous + EM Jurassic Echuca Shoals SR oil & gas + Plover gas; EchucaS. reservoir
Rollet et al., 2016, A regional assessment of CO2 storage potential in the Browse Basin, Record.2016.017
Extent of Mesozoic Petroleum Systems
AOGC Fremantle, 2016
Heywood Graben
Westralian 1 Early – Middle Jurassic gas Plover–Plover Fm
Westralian 2/3 Caswell Jurassic-Cretaceous wet gas Vulcan Fm–Brewster Mbr
Westralian 1 + 2 Heywood Jurassic oil & gas Plover/Vulcan coals–Nome
Westralian 3 + 1 &/or 3+2 E Cretaceous + EM Jurassic Echuca Shoals SR oil & gas + Plover gas; Echuca reservoir
Source & reservoir rocks
No data
Sources of Hydrocarbons
Westralian 2/3 Jurassic wet gas Vulcan–Brewster mbr
Biodegraded
Westralian 1 E-M Jurassic gas Plover–Plover Fm
Westralian 3 + 1 &/or 3 + 2 E Cret oil & gas + Jurassic gas Echuca Shoals–Echuca S./Jamieson
Scott Reef 1
Fluvio-deltaic
Open marine
Marine
AOGC Fremantle, 2016
10 20 30 40 50 60 70 80
89.98
9010 20 30 40 50 60 70 80
89.98
9010 20 30 40 50 60 70 80
89.
99
90
Bulk Fluid Composition; Gas Chromatograms
• Gwydion-1 • Cornea
n-alkanes C16 – C34 max C21 Pr/nC17 = 2.21
Pr/Ph = 2.90 Prominent UCM
AOGC Fremantle, 2016
#10262 #10170
n-alkanes removed Pr/nC17 removed Pr/Ph removed Prominent UCM
Ph
nC18
nC25
UCM
Pr
nC21
nC32 UCM
10 20 30 40 50 60 70 80
89.
92
9010 20 30 40 50 60 70 80
89.95
9010 20 30 40 50 60 70 80
89.95
90
Bulk Fluid Composition; Gas Chromatograms • North Scott Reef-1 condensate
49-54° API gravity • Caswell-2 “oil” 47° API gravity
(gas/condensate with higher HMW compounds)
n-alkanes C5 – C32 max C10 Pr/nC17 = 0.22 Pr/Ph = 2.99 CPI = 1.52 Ideal CGR = 12 bbls/MMscf
AOGC Fremantle, 2016
#10169 #922
n-alkanes C5 – C32 max C11 Pr/nC17 = 0.51 Pr/Ph = 2.94 CPI = 1.58
Pr
nC17
nC13
nC10
Pr
nC17
nC13
Ph
nC11
nC8
nC26
nC7
nC28
Sources of Hydrocarbons: Gases
Grosjean et al., 2016
neo-pentane is resistant to biodegradation
AOGC Fremantle, 2016
Sources of Hydrocarbons: Gases
neo-pentane is resistant to biodegradation
Evidence for mixing in n-alkane-specific 13C isotopic signatures
Yampi Shelf accumulations believed to contain J10-J20 (Plover) gas & K20-K30 (Echuca Shoals Fm) ‘light oil’
Gases with depleted 13C signatures
Yampi Shelf biodegraded gases with enriched 13C signatures
Gases with enriched 13C signatures
AOGC Fremantle, 2016
Gases with intermediate 13C signatures
Crux
Sources of Hydrocarbons: Fluids
Updated from Edwards & Zumberge, 2005
List of (significant) parameters Bulk 13C sats, aroms C19/C23 tricyclic terpanes C22/C21 tricyclic terpanes C24/C23 tricyclic terpanes C24tetracyclic / C23 tricyclic terpanes C27 tetracyclic / tricyclic terpanes C28/C30 hopane C29/C30 hopane C30 diahopane / C30 hopane C31 22R/C30 hopane Sterane/hopane %C27:C28:C29 αββ steranes 20S C27 βα diasterane 20S / C27 ααα sterane 20R C27Ts/Tm & C29Ts/Tm Pr/Ph not discriminatory & biodegraded
AOGC Freemantle, 2016
Early Cretaceous Echuca Shoal Fm (‘light oil’) + Plover (gas) SR
L. Jurassic-E. Cretaceous Vulcan Fm SR
Coaly SR Jurassic Plover /Vulcan Fm
Early-Middle Jurassic Plover Fm D/E SR
Bulk Carbon Isotopes
AOGC Fremantle, 2016
Marine
Terrestrial
Biodegradation
Ichthys Brewster Mbr
Kronos Scott Reef Torosa, Brecknock
Crux de
plet
ed
enric
hed
depleted enriched
Caswell
Browse Basin Oil/Condensate Families Source Parameters: Steranes and Terpanes
AOGC Fremantle 2016
Octans Libra Biodegradation
Ichthys Marine
Terrestrial
Scott Reef & N. Scott Reef
Calliance
Brecknock
Aromatic Hydrocarbon Maturity Parameters Increasing maturity • Caswell least mature
Libra Octans
Crux
• Caswell least mature
• Ichthys most mature,
• Scott Reef Trend Plover-gases, increasing maturity from SW to NE
Kronos
Kronos-1
Torosa (Scott Reef & N. Scott Reef)
Brecknock
Calliance
• Caswell least mature
• Ichthys most mature
• Scott Reef Trend Plover-gases, increasing maturity from SW to NE Gorgonichthys 1
Dinichthys N. 1
North; Scott Reef Trend
South
AOGC Fremantle, 2016
Browse Basin Oil/Condensate Families
Ichthys Brewster Mbr, wetter gases 55º
Kronos Mature, driest gases
Gorgonichthys 1, Dinichthys N.1
Scott Reef Torosa, Kronos
~50°
Crux 47º
Gas Wetness and API gravity with Depth
AOGC Fremantle, 2016
Saturation Pressure (Psat) Indicates Dew Point Systems
Bubble point
Dew point
Browse fluids
Global empirical phase behaviour ?Drilling fluid
contamination
Adele
AOGC Fremantle, 2016
Browse Gases are Typically Undersaturated
AOGC Fremantle, 2016
Reservoir fluids at Psat = condensate
Overpressure at Argus Crux
Calliance
Torosa
Mature, driest gases Zephyros, Kronos, N. Scott Reef Trend
Saturation Pressure (Psat) Indicates Dew Point Systems
AOGC Fremantle, 2016
Scott Reef Trend Plover Fm source & increasing maturity
Adele-1, Caswell Sub-basin Echuca Shoals Fm source
Psat
(dew
poi
nt),
psi
North; Scott Reef Trend
South
Saturation Pressure (Psat) Indicates Dew Point Systems
AOGC Fremantle, 2016
Note: No gas at Caswell no CGR; API = 47°
Psat
(de
w p
oint
), ps
i
Adele-1
AOGC Fremantle, 2016
Regional Sources of Petroleum Fluids: Summary
Montara
Montara
Laminaria Corallina
Laminaria Corallina
Bard 1 Elang West 1
Elang West 1
Bard 1
Conclusions • Geochemical signatures provides new insights into the petroleum prospectivity
• Unaltered fluids have high API & CGRs; plot on dew point pressure curve
• Characterise 4 dew point petroleum systems comprising condensate & gas families; Plover (J10-J20) sourced gas is pervasive both laterally & vertically; maturity trends Vulcan (J50-K10) locally sourced wetter gases in the Brewster Mbr Echuca Shoals (K20-K30) sourced gas and condensate/‘light oil’ Difficult to determine an Early Cretaceous Echuca Shoals end-member: Gas at Adele.
Mixture at Caswell. Yampi Shelf accumulations contain biodegraded ‘oil’ + Plover-sourced gas Plover/Vulcan (coal) sourced gases Crux, Heywood Graben
• Jurassic-Cretaceous source rocks are typically gas-prone, with some liquids potential
• Regional correlations to other liquids-rich accumulations
AOGC Fremantle, 2016
Acknowledgements
GA Repository: Jamie Lankford GSWA Repository: Paul Stephenson GeoMark GA Laboratories: Junhong Chen, Ziqing Hong, Neel Jinadasa
Resources Division [email protected]
GA Repository: Jamie Lankford GSWA Repository: Paul Stephenson GeoMark: Kendra Imbus, Greg Getz GA Laboratories: Junhong Chen, Ziqing Hong, Neel Jinadasa
Resources Division [email protected]
© Commonwealth of Australia (Geoscience Australia) 2016 . With the exception of the Commonwealth Coat of Arms and where otherwise noted, this product is provided under a Creative Commons Attribution 4.0 International Licence. http://creativecommons.org/licenses/by/4.0/legalcode
Image: Noble Clyde Boudreaux development drilling of Prelude courtesy of Shell Australia
