1) The document summarizes the tectono-stratigraphic evolution of the Taranaki Basin in New Zealand from the Late Cretaceous to present. 2) There were four main periods of deformation involving extensional faulting during rifting (84-55 Ma), contraction and inversion of faults during subduction (55-25 Ma), and recent low extension in the North Taranaki Graben. 3) Fault reactivation during the Eocene-Miocene inversion and Pliocene extension resulted in migration of hydrocarbons but also potential leakage through breached faults, representing a primary risk factor.

1. Fault
Isaac Kenyon
isaackenyon3@gmail.com
MSc in Petroleum Geoscience 2016 Department of Earth Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 0EX
2-D Tectonic Evolution
Tectono-Stratigraphic Framework
4-D Tectono-Stratigraphic Evolution
Structure of the Southern Inversion Zone
Conclusions Implications for Prospectivity
Tectonic Setting of the Taranaki Basin1 3
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Tectonostratigraphy & Inverted Faults, Taranaki Basin
related to hydrocarbon plays in the Taranaki .Basin
Maui-4 Well
theof
Introduction:
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The study area is 330,000 km and consists
Location map & plate tectonic setting Structural map
Aims:
Pre-Extension Syn-Extension 1 Post Rift 1 Post Rift 2 Post Rift 3 Post Rift 4 Syn & Post Inversion Syn-Extension 2
Unconformity Fault Bedforms/
Horizons
(Pre E.Cretaceous
Basement)
(L.Cretaceous) (Paleocene
&Eocene)
(Oligocene) (Miocene) (Plio-Pleistocene)? ?
Geological Setting: Is a continuum evolution from an intra-continental rift to a convergent margin to a recent extensional back-arc basin
Extensional faulting (~84-55Ma)
coinciding with seafloor spreading
between Australia, Antarctica
& New Zealand.
Onset of contraction due to
subduction along the Hikurangi
Margin (~55-25Ma).
Developing contraction
reactivated pre-existing
extensional faults inverting
NNE-SSW trending faults.
Low regional recent extension
due to back-arc rifting
in the North Taranaki Graben.
Potential negative inversion
of reactivated of pre-existing
inverted graben faults.
Active faults focus in the Northern study area. of Pleistocene faults are active today.
Extensive widespread transgression.Faults begin to grow larger through linkage.
Schematic 2-D Reconstructions (N-S inline):
Fault Map
Isochron
Maps
Time Thickness Map
Syn-Extension 1
Time Thickness Map
LateCretaceous
A A’
Post-Extension 1
Early Palaeocene to
Early Miocene (80-25Ma)(115-110Ma)
B B’
Post Inversion to Surface
Time Thickness Map
Early Miocene to Recent
(22-0Ma)
C’C’
Taranaki Basin Play Cross Section
Conclusions
Four main periods of deformation from the Late Cretaceous to Recent.
Locations and orientations of faulting are influenced by the locations and orientations of previous faults during plate tectonic reorganisation.
Seal rock: two phases of clastic mudrock deposition:-
Passive margin transgressive phase (Paleogene).
Reservoir rock: present in all chronostratigraphic levels from Palaeocene to Early
Pliocene.
Petroleum Elements
Oil Generation: occurred in a SE-NW trend from the Late Cretaceous, peak oil
Paleocene to Early Miocene.
Migration: up-dip through basinal faults during periodic reactivation.
Primary Risk: Gas leakage through reactivated faults.
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Source rock: mainly terrestrial sources with minor marine contribution.
Regressive margin phase (Neogene).
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only producing petroleum basin.
Kupe Region and Southern Inversion Zone
regional structures.
1 Model a tectonostratigraphic evolution of
the Taranaki Basin to understand the
implications of structures on NZ’s plate
boundary settings.
2 Identify precise locations of Inversion
along individual faults during the Eocene
to Miocene compression as well as
2-D Regional Line
The Taranaki Basin is currently New Zealand's
negative inversion and fault reactivation
3 Understand the implications of fault
reactivation with hydrocarbon migration.
during the Pliocene extension.
Traps: primary trapping mechanisms are structural traps (Inversion structures) and
normal fault blocks secondary traps are stratigraphic pinch outs.
X
Y
(X-Y)
Isochron from basement to Isochron from top Isochron from the post inversion
Syn-inversion growth. Contractional relaxation extension.
Fault reactivation during Plio-Pleistocene extension and Eocene-Miocene compression result in fault breach and migration of gas.
Early Miocene Contractional Recent Extensional
Fault Architecture
Analysis
Risk analysis cross-section of fault breach
Figure 2:Figure 1:
Figure 3a: Uninterpreted 2-D regional line (NW-SE trending) with reflection amplitude attribute, transecting across the Maari 3-D survey.
Figure 3b: Interpreted Fig.3a showing stratal layout i.e. megasequences.
Figure 4: Chronostratigraphy and Seismostraigraphy of the Taranaki Basin combined.
Figure 6a: Uninterpreted crossline (B-B’)Figure 5a: Uninterpreted crossline (A-A’)
Figure 10c: Thermal subsidence.
Figure 10a: Original basement.
Figure 10d:
Figure 10b: NW-SE trending extension.
Figure 10e:
Figure 9b: Figure 9c:IFigure 9a:
Figure 10f: Recent deposition.
Figure 11d: Post Inversion horizon and Figure 11e: Syn to Post Extension horizon. Figure 11f: Recent deposition. Only 10%
Figure 11c: Post-Extension horizon.Figure 11b: Syn-Extension horizon.Figure 11a: Pre-Extension horizon. 1st
Figure12:
Figure 6b: Interpreted crossline showing negative inversionFigure 5b: Interpreted crossline showing inversion.
Evolution
Figure 7a: Pre-Extension
Basement (Mid Cretaceous).
Figure 7b: Syn-Extension 1
(Late Cretaceous).
Figure 7c: Post-Extension 1
(Palaeocene).
Figure 7d: Post-Inversion
(Early Miocene).
Figure 7e: Syn-Post
Extension 2 (Early Pliocene).
C C’
Figure 8b: Geobody of Syn-Extension 3 horizonFigure 8a: Coherency attribute of the Miocene
erosional hiatus unconformity.
stage of deformation, pre-existing fault
architecture for later reactivation.
Fault Architecture
Pliocene
unconformity to the surface seabed.post-extension to start of inversion.syn-extension.Central depocenter
palaeoflow to the SE.
The Pliocene extensional
phase represents an
immature fault system
with faults achieving large
strike dimensions over a
short period of time.
Typical evidence for rapid
growth of faults are:
- relay ramps
- linking up of smaller segments
- overlapping faults
attached to a Post Inversion seismic probe.
The Miocene
consists of a series
of recently
developed faults
and reactivated
faults and is an
excellent interval to
observe fault
growth structures
such as: sigmoidal
shears, breached
relay ramps and
wing tips.
base Post Inversion horizon.
Basin
Evolution
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2
3a
3b
4
5b
5a
10d 10e 10f
10a
10b
10c
7a 7b 7c 7d 7e
8a
8b
9c
11a 11b 11c
11d 11e 11f
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6a
6b
9b9a
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