RECENT ADVANCES IN UNDERSTANDING TARANAKI PETROLEUM SYSTEMS: THE KUPE - MANAIA FAIRWAY KF Kroeger, R Funnell, M Fohrmann, M Hill Undiff. Mid-Late Cretaceous Rakopi Fm North Cape Fm Farewell Fm Otaraoa Fm Murihiku/Brook Street Basement Otaraoa Fm Taimana Fm Manganui Fm Manganui Fm Median Batholith Otunui Fm Otunui Fm Mangaoapa Mbr Mangaoapa Mbr Matemateaonga Fm Matemateaonga Fm Tangahoe Fm Tangahoe Fm Whenuakura Fm Whenuakura Fm 0 Kupe South-3 Kupe South-2 A A’ 1 2 3 4 5 6 7 8 9 10 Depth (km) Fluvial Facies/lithology units Coal measures Shoreface/shallow marine Shelf Coastal plain Outer shelf/slope Bathyal Bathyal (marly) Submarine fan Submarine channel Volcaniclastics Undiff. Mid-Late Cretaceous Rakopi Fm North Cape Fm Farewell Fm Murihiku/Brook Street Basement Otaraoa Fm Taimana Fm Manganui Fm Otunui Fm Mangaoapa Mbr Matemateaonga Fm Tangahoe Fm Whenuakura Fm 0 Kapuni-13 Kapuni-8 B B’ 1 2 3 4 5 6 7 8 9 10 Depth (km) 11 A Introduction The remapping of the Taranaki Basin as part of the 4D Taranaki project at high resolution has produced a wealth of new data. Digital integration of well data, sequence stratigraphy, paleogeography and structural interpretation has improved our understanding of basin architecture and evolution. These data have been used to build a high resolution 3D PetroMod™ petroleum systems model intended to shed light on charge of traps and preservation of petroleum accumulations in the basin. Forward modelling of the basin structure Detailed reconstruction of the basin architecture and evolution through time has led to a new interpretation of carrier bed geometry. The evolution of the southeastern Taranaki Basin was characterized by initial submergence along with the formation of the convergent plate bounday in the east, followed by Late Miocene inversion, renewed subsidence and uplift of the Taranaki Peninsula. This evolution shaped the structure along the crest of tha Manaia anticline, influenced closure, for instance at the Toru-1 well location, and controlled migration along the N-S fairway. Thermal Model To reproduce petroleum generation history, the 3D thermal evolution of the area was modelled, using Regional heat flow history (Kroeger et al. 2013) Well data (temperature and vitrinite reflectance) for calibration Standard organofacies Type III DE kinetics Seismic interpretation and grids from Fohrmann et al. (2012) 1 2 3 4 The 3D model consists of 15 layers interpreted from seismic data (Fohrmann et al. 2012) and has been further subdivided to represent facies zonations of Strogen (2011). Images show lithological architecture along east-west (A-A’) and north-south (B-B’) transects through the model. A B C Rakop Formation Farewell Formation Mangahewa Formation Above figures show the evolution of the crest of the Manaia Anticline (”Manaia Fairway”) from mid Miocene to Recent time along a N-S transect N N N 0 Ma 6.5 Ma 8.5 Ma 16 Ma S N Above figure shows predicted petroleum generation (tons/m )l of A) Rakopi, B) Farewell, and C) Mangahewa Formation between Manaia and Taranaki faults. In addition, A shows modelled faults, B shows main migration pathways and predicted accumulations as well as contribution of source rocks to Kupe accumulation. 2 within Farewell Formation Age (Ma) 100 0 Petroleum generation and migration modelling Petroleum systems modelling of the area has provided greater detail on the timing of source rock maturation and factors controlling petroleum migration. Compared to previously published data (i.e., Taranaki Atlas), a revised velocity model has led to a new interpretation of burial depth of source rocks. Deeper burial and therefore higher maturity could partly explain the gas proneness of this part of the basin. Migration was controlled by the changing geometry of the Manaia Anticline and faulting of the carrier beds and reservoirs. Later stage faulting affected seal integrity. Results and Conclusions Farewell Formation is predicted to be the most important source rock in the Kupe region. This is consistent with geochemical data (Sykes et al. 2012) Mangahewa Formation has the potential for generating petroleum in the onshore but little charge to the south is predicted Gas-proneness of the Kupe Field is explained by main charge from mature source rocks in Farewell Formation north of the Toru-1 well with additional recent charge from Farewell coal seams proximal to the field The geometry of the Manaia Fairway and trap closure is controlled by the history of burial and basin inversion References Fohrmann, M., Hill, M., Reid, E., King, P.R., Zhu, H., Roncaglia, L., Bland, K.J., Strogen, D.P., Scott, G.P.L., 2012. Seismic reflection character, mapping and tectono-stratigraphic history of the Kupe area (4D Taranaki Project), south-eastern Taranaki Basin, GNS Science Report 2012/36. GNS Science, Lower Hutt. 62pp Kroeger, K.F., Funnell, R.H., Nicol,A., Fohrmann, M., Bland, K.J., King, P.R., 2013. 3D crustal-scale heat-flow regimes at a developing active margin (Taranaki Basin, New Zealand).Tectonophysics 591, 175-193. Strogen, D.P., 2011. Updated paleogeographic maps for theTaranaki Basin and surrounds, GNS Science Report 2010/53, Lower Hutt, 83pp. Sykes, R.; Zink, K.-G.; Rogers, K.M.; Phillips,A.; Ventura, G.T. 2012. New and updated geochemical databases for New Zealand petroleum samples, with assessments of genetic oil families, source age, facies and maturity. GNS Science Consultancy Report 2012/37, 29pp Acknowlegements This research was undertaken with Crown funding provided through the New Zealand Ministry of Business, Innovation and Employment (MBIE). Data used for high- resolution modelling were developed as part of the 4D Taranaki project and we thank all GNS staff involved. We also thank Schlumberger for access to PetroMod™ software. Kapuni-13 Kapuni-8 Tahi-1 Toru-1 Water Depth 0 100 200 300 400 500 16 km Taranaki Peninsula Kupe South-1 Kupe South-2 Kupe South-3 Kupe South-4 Kupe South-5 Kupe-1 A A’ B B’ 1D thermal history at Kupe-1 well site extracted from the 3D model showing: (1) passive margin evolution and initial burial of the Taranaki Basin (2) convergent margin evolution and cooling due to crustal thickening (3) Late Miocene uplift and erosion (4) Pliocene-Recent burial stage most relevant for petroleum formation. Pliocene-Recent Miocene Eocene-Oligocene Paleocene Cretaceous Manaia Fault Manaia Anticline (TOC = 3 mg/g) (TOC= 3-8 mg/g) (TOC = 3.5 mg/g) Manaia Fairway Predicted Petroleum Composition Institute of Geological and Nuclear Sciences, PO Box 30368, Lower Hutt 5040, NEW ZEALAND