Facies Distribution and Impact on Petroleum Migration in ... · Facies Distribution and Impact on...
Transcript of Facies Distribution and Impact on Petroleum Migration in ... · Facies Distribution and Impact on...
GNS Science
Facies Distribution and Impact on Petroleum
Migration in the Canterbury Basin, New Zealand
Tusar R. Sahoo1, Karsten F. Kroeger1, Glenn Thrasher1, Stuart Munday2,
Hugh Mingard3, Nick Cozens2 and Matthew Hill1
1 GNS Science, Lower Hutt, New Zealand 2 New Zealand Oil & Gas, Wellington, New Zealand 3 Mingard Geoscience Ltd, Christchurch, New Zealand
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Seismic data coverage and drilled wells
2D/3D Seismic data:
Reprocessed seismic lines and acquired
seismic lines since 2006 are of reasonable
quality for facies interpretation.
Waka3D is of very good data quality for
facies interpretation.
Sub-commercial gas-condensate discovery:
Clipper-1 and Galleon-1
Oil & Gas shows:
Cutter-1 and Caravel-1
Study area
Caravel-1
Waka 3D
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Objectives of this study
• Producing an updated series of paleogeographic maps
showing source, reservoir and seal rock distribution
• Understanding key risks associated with petroleum system
elements using a 2D basin modelling
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Overview of talk
• Stratigraphic framework
• Seismic facies characterisation
• Paleogeographic maps
• 2D petroleum system modelling
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Stratigraphic framework
Clipper-1
Rifting started in mid Cretaceous
(~ 105 Ma; Davy, 2014)
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Early Oligocene erosion Isopach map between Paleocene (P10)
and Eocene (P50)
a
top Oligocene ?
top Eocene
channels
channels
channels
Coherency map at top Eocene
b
c Waka 3D
Waka 3D
Clipper-1
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Seismic facies characterisation
Galleon-1
followed approach by
Mitchum and Vail (1977)
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Seismic facies characterisation
Facies Seismic reflection character
Amplitude Lateral continuity Geometry
Alluvial fans Low-moderate Discontinuous-low Chaotic, steeply dipping, wedge like
Fluvial facies Variable Discontinuous-low Chaotic-sub-parallel
Coastal sandstone & siltstone
Moderate Moderate-continuous Parallel to sub-parallel and part of sigmoidal deltaic unit
Coastal coal measures High Moderate-continuous Parallel to sub-parallel and part of sigmoidal deltaic unit
Shoreface sandstone & siltstone
variable Low on dip direction Parallel-slightly divergent
Shelfal sandstone & siltstone
Moderate-high Moderate-high Parallel, distal part of sigmoidal deltaic unit
Shelfal mudstone Low Low Parallel
Bathyal mudstone Low-moderate Variable Parallel
Co
asta
l M
arin
e
Terr
est
rial
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Seismic facies characterisation
b
c
b c
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Paleogeographic maps
Syn-rift levels
coal measures
of Clipper Fm.
coal measures
of Clipper Fm.
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Paleogeographic maps
Post-rift levels
coal measures of
Pukeiwitahi Fm.
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Paleogeographic maps
Post-rift levels
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mid Cretaceous; 85 Ma Basement
top Paleocene
top Cretaceous
top Miocene
2D petroleum system model
Tartan Fm.
• Source rock parameters and kinetics are
taken from Sykes and Funnell (2002)
• Average heat flow: ~ 62 mW/m2
Dep
th (
m)
1000
2000
3000
4000
5000
6000
7000
8000
Clipper-1
20 km
Clipper-1
Igneous intrusion
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Model calibration at Clipper-1
Vitrinite reflectance being
supressed by their perhydrous
nature (Newman et al., 2000;
Sykes & Funnell, 2002)
Gibbons & Herridge (1984)
VIRF data, Newman et al., (2000)
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20 km
Present day maturity
Igneous intrusion
Basement top mid Cretaceous
top Cretaceous
top Paleocene
Maturity (%Ro) Sweeney & Burnham (1990)
Clipper-1 Pseudo well-1 Pseudo well-2
Tartan Formation
Dep
th (
km
)
1
2
3
4
5
6
7
8
Early mature
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Cumulative expelled petroleum at 1D locations
Clipper-1
Pseudo well-1
Pseudo well-2
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2D migration model
20 km Basement
top mid Cretaceous
top Cretaceous
Clipper-1
Tartan Formation
Dep
th (
km
)
1
2
3
4
5
6
oil and gas
accumulation
Hydrocarbon (gas)
accumulation
Igneous intrusion
75 Ma
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Summary
Source rocks:
• Mid Cretaceous coaly source rocks (Clipper Formation) are widely distributed and are
considered to be the primary source rock in the basin, as they are sufficiently mature to
expel hydrocarbon.
• Late Cretaceous coaly source rocks (Pukeiwitahi Formation) are restricted to the
southwestern part of the basin and may have generated hydrocarbon beneath the
prograding Neogene foresets.
Reservoir rocks:
• In general, reservoir quality in the fluvial and coastal facies may be limited, and is likely
better in the shoreface–shelfal facies.
Seal rocks: • Shelfal mudstones are widely distributed in the Late Cretaceous and in the Paleocene
section and have the potential to act as a seal rock.
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Key risks:
• Early expulsion from the primary source rock (mid Cretaceous) and associated risk related
to the requirement of early seal development to preserve accumulated volumes.
• Heterogeneity in potential reservoir rocks.
• Limited maturity and distribution of Late Cretaceous source rocks.
Accumulation:
• Most of the predicted accumulations along the modelled section contain gas because early
accumulated oil has been replaced by the later expelled gas.
Summary
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This work was undertaken as part of the Petroleum Basins Research Programme with direct
Crown funding from the New Zealand Government (Ministry of Business, Innovation and
Employment). Part of the seismic interpretation, seismic facies mapping and
paleogeographic mapping were funded by New Zealand Oil & Gas (NZOG) and Beach
Energy Limited. We would like to thank NZOG and Beach Energy Limited for their support
and permission to publish this work. We would like to thank Paradigm and Schlumberger for
providing access to SeisEarth and PetroMod software respectively.
Acknowledgements:
Thank you for your attention.