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Fault Isaac Kenyon [email protected] 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 Basin 1 3 5 6 4 2 Tectonostratigraphy & Inverted Faults, Taranaki Basin related to hydrocarbon plays in the Taranaki . Basin Maui-4 Well the of Introduction: 2 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. 1 2 Source rock: mainly terrestrial sources with minor marine contribution. Regressive margin phase (Neogene). 1 2 3 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: I Figure 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 inversion Figure 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 horizon Figure 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 1 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 12 6a 6b 9b 9a ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
