Reservoirs of Taranaki Basin, New Zealand: from Source to Sink

Reservoirs of Taranaki Basin, New Zealand: from source to sink

K. Higgs GWL / PESGB Cluster Meeting, May 2018 Acknowledgements

This project was undertaken by GNS, funded by the Petroleum Basin Research (PBR) programme via the Strategic Science Investment Fund from the New Zealand Government (MBIE).

• NZP&M sample / data / petroleum report repository • Student theses (Hopcroft, 2009; Shumaker, 2016) • GNS PETLAB database

Thanks also to the numerous contributors to this work, including:

Co-author

Peter King Chris Nick Andy Greg Dominic Adams Mortimer Tulloch Browne Strogen GNS Science Talk Outline

• Who are GNS Science?

• Introducing Zealandia and Taranaki

• Composition: sandstone vs basement

• Provenance and basin evolution

• Diagenetic alteration and implications for reservoir quality

GNS Science GNS Science

• Government-owned research company (CRI)

• Earth and isotope scientific research and consultancy

• Over 150 years experience New Zealand geology

• Over 350 staff (c. 75% Wellington, 25% Taupo, 5% Dunedin)

Purpose of Organisation: • to understand earth systems

• to transform this knowledge into economic and social benefits for New Zealand

GNS Science Formation of Zealandia, Early-Late Cretaceous

Early Cretaceous c. 150 million years ago Late Cretaceous c. 75 million years ago

End Cretaceous c. 65 million years ago

Rift basins in central west, possibly part of a transform system linked to sea- floor spreading McSaveney and Sutherland, 2005 GNS Science Zealandia 1st-order Late Oligocene megasequence c. 25 Ma W E Southwards propagation 0 of Pacific subduction zone; pervasive subsidence & Regressive maximum marine inundation

20 Distal hiatus Maximum base level rise Composite unconformity Middle Eocene Development of c. 40 Ma 40 precursor Erosion boundary between Australian & Age(Ma) Transgressive Pacific plates 60

Latest Paleocene Post-rift passive c. 55 Ma 80 Regional onlap of basement begins margin, NZ drifting from Antarctica

Syn-rift 100 Basement

Chronostratigraphy after King et al., 1999; tectonic reconstructions aftter King, 2000 GNS Science Zealandia 1st-order megasequence Pliocene W E 0 c. 5 Ma

Regressive

20 Distal hiatus Maximum base level rise Composite unconformity

40 Late Miocene Widespread c. 10 Ma Erosion compression. Clockwise rotation

Age(Ma) Transgressive of subduction margin & oblique 60 convergence along Alpine Fault

Early Miocene 80 Regional onlap c. 20 Ma Start of long-lived of basin begins regression. Alpine Fault propagated between Syn-rift subduction zone and southern rift; compression 100 and development of fold- Basement thrust belt in Taranaki

Chronostratigraphy after King et al., 1999; tectonic reconstructions aftter King, 2000 GNS Science Present-Day Configuration

NZ has a vast offshore 2 Challenger territory, ~5,800,000 km Plateau Hikurangi Plateau Sedimentary basins cover a Chatham Rise Australian large part of the EEZ and Plate ECS (~1,700,000 km2)

Campbell All are frontier basins with Plateau the exception of Taranaki Pacific Plate

Taranaki is currently the only producing sedimentary basin Subduction along Hikurangi margin and in New Zealand transpression on Alpine and splay faults

GNS Science New Zealand Basement

Western Province – basement and cover rocks from Gondwana craton (Cambro-Ordovician)

Plutonic rocks - mostly comprising Median and Karamea batholiths (dominant Cretaceous- Jurassic & Devonian)

Eastern Province – elements of the arc-trench-subduction system active along E Gondwana margin (Triassic-Late Cretaceous)

General New Zealand basement map (from Turnbull & Allibone, 2003; Mortimer, 2004) and inset Taranaki summary basement map (modified from Mortimer et al., 1997 and Tulloch et al., in prep.)

GNS Science W-E Schematic Cross Section

Mt Taranaki Taupo Volcanic Zone

Volcanics A llo Basin-fill sediments ch th on W s Sea level E

Unconformity t n e

m Hikurangi e Australian Trough s Moho

a Plate B Western Eastern Pacific Plate

Figure after Mortimer, 2014 GNS Science Northwest Southeast

Regressive Phase Active margin Overthrusting on Transitional Taranaki Fault

Transgressive Phase rift to passive margin -

“Early syn-rift”

Syn Breakaway from Gondwana

Figure after Bland et al., 2014 GNS Science Reservoir Facies Transgressive: Reservoirs are mostly fluvial, marginal or shallow marine

Regressive: Turbidite reservoirs

Photos from GNS researchers GNS Science Stratigraphic differences in mean grain size

Regressive System Deposits (n = 272)

Miocene (Active Margin)

Transgressive System Deposits Oligocene (Transitional) (n = 805)

Paleogene (Passive Margin)

Cretaceous (Syn-rift)

Grain Size vf = very fine f = fine m = medium c = coarse vc = very coarse l = lower u = upper

Thin section data from: PEGI (Higgs et al., 2012) GNS Science Coarse & granular Rakopi Fm V fine grained Mt Messenger Fm Alluvial/fluvial facies Deep Water facies Transgressive System Deposits Regressive System Deposits

Photos from GNS researchers GNS Science Stratigraphic differences in detrital mineralogy

Thin section data from: PEGI (Higgs et al., 2012), 2012-15 open-file PR reports (GNS), Kauri Sand Study (GNS with Kaimiro/Mangahewa n = 255 permission from Swift Energy)

Tariki/Matapo n = 60

McKee/Tangaroa Moki; n = 36 n = 31 Mt Messenger Mean data Farewell n = 33 n = 36 Urenui One std dev around the mean Rakopi/N Cape n = 15 n = 62 Oligocene sst outcrop n = 10

Kauri n = 16

Sandstone classification scheme from Folk et al.,1970 GNS Science Correlation between mineralogy and basin history

Syn-rift to passive margin deposits (transgressive system) Late transitional deposits (Late Oligocene/Early Miocene)

Active margin deposits (regressive system)

Mean data

One std dev around the mean

GNS Science Correlation of mineralogy to basement source

Q TS data from: Brook St/ 0 Tuhua Intrusives 100 GNS PETLAB Drumduan Buller Other W Province n = 30 Basement (published data & theses E Prov terranes Rocks as referenced in PETLAB) Torlesse n = 301 Dun Mtn/ Maitai Karamea n = 22 Waipapa Darran n = 103 Buller

Karamea Inner n = 10 Caples Median n = 43 Batholith Brook St Volc. n = 14

Batholith 100 0 F 0 L Reservoir Murihiku Dun Mtn/Maitai n = 169 n = 183 Rocks

Map modified from Mortimer et al., 1997 and Mortimer et al., in prep.)

Basement map after Tulloch et al., in prep. GNS Science Mineralogy trends in syn-rift to passive margin deposits (transgressive system)

Q Plag 0 Q = total quartz Plag = plagioclase 0 100 100 F = total feldspar KF = K-feldspar Kaimiro/ L = lithic fragments M = detrital mica Mangahewa Eocene younging Paleocene Cretaceous

Farewell Farewell

Rakopi/ N Cape

Rakopi/N Cape Kaimiro/ Mangahewa

100 100 0 0 F 100 0 L+M KF 100 0 M

Cretaceous – most primitive, mica and lithic-rich Paleocene (Farewell) – intermediate composition, plag-rich Eocene – most mature, quartz and K-feldspar rich

GNS Science U-Pb zircon geochronology results Syn-rift (Cretaceous): Early Transition: Active Margin: zircon mostly derived from zircon mostly derived from zircons support multiple local basement rocks granites but some EP sources, significant E source in the NE Province component

Cretaceous

Late Eocene Miocene

Mid-Oligocene

Zircon ages from Adams et al., 2016 Zircon ages from Kamp, 2012 Zircon ages from and Tulloch & Turnbull, 2014 and Hopcroft 2009 Shumaker, 2016

Separation Pt Suite Buller/Takaka Undiff metasedimentary terranes Plutonic Darran Suite Source Western Province Eastern Province Karamea Suite GNS Science Syn-rift: Local basement provenance dominated by first cycle source from Tuhua Intrusives

T Tuhua Intrusives Cretaceous 65-75 Ma: active rift transform Other W Province WP zone with development EP E Prov terranes of small rift grabens

Coastal plain facies Shoreline/shoreface EP: Inferred Offshore marine facies Median Batholith subdued Submarine fan facies topography

K Karamea source M Median batholith source Eastern Prov source Exposed & eroding Western Prov source Paleozoic Eroded sedi source terranes & plutons Volcaniclastic source

Figure from Higgs and King, 2018; paleogeography after Strogen, 2011; basement after Mortimer et al. (1997) GNS Science Post-rift, passive margin: 1st & 2nd cycle from intrusives in the south, longer transport distances, some re-working

Paleocene (60 Ma): waning Eocene (40 Ma): incipient rifting; residual rift subduction to the far north; transform in the south uplift and tilting in southern margin of basin

Erosion of EP: Inferred sediment subdued topography

Figures from Higgs and King, 2018; paleogeography after Strogen, 2011; basement after Mortimer et al. (1997) GNS Science Early transition (35-27 Ma): Erosion of cover rocks with progressive unroofing from N to S Latest Eocene (35 Mid Oligocene (28 Ma): plate Ma): local uplift in the boundary established & north associated with uplift propagated southward fledgling A-P plate boundary zone

Figures from Higgs and King, 2018; paleogeography after Strogen, 2011; basement after Mortimer et al. (1997) GNS Science Late transition (21 Ma): Fine-grained, lithic-rich sediments derived from Eastern Province terranes

Onset of regression; piggy-back basins and uplift in the east

Earliest Miocene Earliest Miocene: Active thrusting on eastern basin margin; provenance from the East

Q Q 0 0 100 100

100 100 0 0 100 0 0 F L F L Latest Oligocene- Eastern Province Earliest Miocene basement

Figures from Higgs and King, 2018; paleogeography after Strogen, 2011; basement after Tulloch et al., in prep. GNS Science GNS Science Active margin (Miocene): Mixed sediment sources with significant Eastern Province component

Mid-Miocene Mid-Miocene: Late Miocene (Moki) Some granitic source in (Mt Messenger) southern basin

Late Miocene: Finer sediments may indicate component of reworked Miocene sediments

Figures from Higgs and King, 2018; paleogeography after Strogen, 2011; basement after Tulloch et al., in prep. GNS Science Photo from GNS researchers GNS Science PRIMARY CONTROLS - grain size Properties at deposition, provenance & - facies related sorting - mineralogy

Implications for Reservoir Quality

SECONDARY CONTROLS Diagenesis, dependent on - compaction depositional properties AND burial, - mineral cement temperature, fluid history - authigenic clay - secondary dissolution

GNS Science Compaction

Syn-rift to passive margin deposits (Transgressive System) Miocene Sandstones: Coarse grain size Quartz-feldspar mineralogy porosity loss by compaction up to c. Less prone to compaction- 20% - much 40% ductile grains induced porosity loss macroporosity reduced to microporosity

Active margin deposits (Regressive System) Cret-Eocene Fine grain size Sandstones: porosity Feldspar-lithic mineralogy loss by compaction c. No ductile grains

30 15-25% - deeper % 20 More prone to compaction- % 10 burial, more complex induced porosity loss % diagenesis

Graph does not include other pore- modifying factors (e.g., cementation / secondary porosity / overpressure)

Compaction curves after Worden et al., 1997 & 2000 GNS Science Empirical net result: reservoir quality is variably controlled by primary and secondary factors

Syn-rift - passive margin deposits Active margin deposits

Reference line 1. Primary Factors - grain size 1. Primary Factors - % matrix 2. Burial (compaction) - % lithics 3. Cementation 4. Dissolution 2. Burial (compaction) 3. Carbonate cement

Conventional core analysis data; plotted from: PEGI (Higgs et al., 2012)

Conventional core analysis data from well completion reports, NZP&M GNS Science Rift-Passive Margin Deposits: Complex Diagenesis

Variable clay and cement type / abundance TYPICAL AUTHIGENIC MINERALS due to different facies / burial / fluid histories - kaolinite / dickite, illite, chlorite, quartz, carbonate

K Pukeko-1 K

Cc SECONDARY Ch Cc POROSITY K Ch Q Q Q Q Cc 2º Ø

2º Ø GNS Science Rift-Passive Margin Deposits: Diagenetic Reactions

1. Aggressive Pore Fluids Mineral Products: Mineral Reactants: Hydrous clay minerals (e.g., Feldspar kaolinite, smectite) Biotite Quartz cement (minor) Chlorite Carbonate cement (localised) Carbonates Heavy minerals Secondary Pores

2. High temperature (>120 ºC) Mineral Reactants: Mineral Products: Hydrous clay minerals (e.g., kaolinite, smectite) Non-hydrous clay minerals (illite, dickite, chlorite) Significant Pressure Quartz cement Solution

Aggressive pore fluids = meteoric water / CO2 from maturation of coals / hydrothermal events, etc. GNS Science Rift-Passive Margin Deposits: Example of Feldspar Reaction (aggressive fluids)

+ + + Feldspar + CO2 + water = kaolinite + silica + K /Na /Ca + bicarbonate kaolinite c. 15% Good: local generation of large secondary pores

Bad: locally pervasive kaolinite or carbonate

GNS Science Rift-Passive Margin Deposits: The good & bad effects of feldspar reaction + + + Feldspar + CO2 + water = kaolinite + silica + K /Na /Ca + bicarbonate

Kaolinite Visible Porosity (14.2%) Bad Example 1) Burial Depth 3,256 m Much feldspar altered to kaolin

Total Porosity 15.8% Visible Porosity 6.5% Permeability 32 mD

Kaolinite Visible Porosity (3.8%) Good Example 2) Burial Depth 3,503 m Significant feldspar dissolution pores

Total Porosity 18.5% Visible Porosity 16.1% Permeability 2270 mD

Figure after Higgs et al., 2017 2 mm GNS Science Rift-Passive Margin Deposits: Example of Illitisation Reaction (high Ts)

Illitised Kaolinite

K-feldspar + kaolinite = illite + silica + water

Bad: micro-porous illite and pore-filling quartz

Illitisation reaction based on K-Ar dates: ~130ºC, 4.5 km Quartz cementation based on FI data: >110ºC, >4 km 20 Age Ma Illitised Kaolinite 60 40

2

TVD km Example 4 Kaolin altered to illite 6 Total Porosity 6.6-14.2% Timing of illitisation ~ intraformational Permeability 0.1-3.3 mD coals mature for oil expulsion (green)

From Higgs et al., 2007 GNS Science Rift-Passive Margin Deposits: Significant illitisation predicted across most of the Taranaki Peninsula

1 mm

1 mm

Depth (m) at 2 Ma

25 km

Kaolinite Depth map, Middle Eocene at 2 Ma (~max. 1 mm Illite/muscovite burial); orange > 4.3 km

Figure after Higgs et al., 2017 GNS Science Provenance vs Reservoir Quality

Syn-rift - passive margin deposits Active margin deposits

Sediment source: Sediment source: Multiple with 1st cycle or recycled Tuhua Intrusives significant E Province & volcanics

Coarse grain size Fine grain size Quartz-feldspar mineralogy Feldspar-lithic mineralogy

Less prone to compaction- More prone to compaction- induced porosity reduction induced porosity reduction

However more deeply buried Relatively shallow burial

Greater compaction (porosity But significant sediment compaction due to reduction), and diagenetic alteration texture & composition; less advanced (porosity reduction & enhancement) diagenetic alteration

GNS Science Key message: understanding provenance is a prerequisite to predicting reservoir quality

• Based on our integrated studies we can predict sandstone texture & composition across the basin

• We can use this information to Reservoir heterogeneity predict the type and level of Burial/temperature history diagenesis Fluid history

• Make an informed prediction of reservoir quality in an undrilled site

GNS Science Looking offshore beyond Taranaki

…..a lot of ground to cover

Photo from GNS researchers GNS Science Thank You

Karen Higgs Email: [email protected]

GNS Science