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Vulcan Sub-basin

Bids close 29 October 2015

  • Adjacent to proven oil-producing province; development planned for nearby Cash/Maple gas accumulation
  • Shallow to deep water depths, 50–350 m
  • Release Areas flank Jurassic depocentre with oil- and gas-prone source rocks
  • Potential for structural and stratigraphic Triassic–Jurassic, Cretaceous and Paleogene plays
  • Special Notices apply, refer to Guidance Notes

Release Areas AC15-1 and AC15-2 are located in the western Bonaparte Basin in the Timor Sea, approximately 300 km offshore and 600 km from Darwin. Release Area AC15-1 (4 graticular blocks) is within the Vulcan Sub-basin, while Release Area AC15-2 (4 full and 4 part graticular blocks) straddles the eastern margin of the Vulcan Sub-basin and the northwest margin of the Londonderry High (Figure 1). Release Areas AC15-1 and AC15-2 are located in water depths of 50–350 m and 50–100 m, respectively.

The Vulcan Sub-basin is a northeast-oriented Mesozoic extensional depocentre that contains Permian–Recent sediments (Figure 2). It is a proven Jurassic hydrocarbon province containing the producing Montara oil field and several depleted oil fields. The hydrocarbon province also includes the Cash/Maple gas and minor oil accumulation which is currently under development, and several sub-economic oil and gas accumulations. Upper Jurassic and Upper Cretaceous submarine fan sandstones are proven exploration targets within the sub-basin. Structural traps containing Triassic to Jurassic sandstone reservoirs are sealed by Lower Cretaceous claystones (Figure 3).

Release Area AC15-1 is on the flank of the Paqualin Graben, less than 5 km from the Oliver oil and gas accumulation to the north and the Pengana gas accumulation to the east. Hydrocarbons at Oliver and Pengana are reservoired in the Plover and Nome formations, respectively. Also nearby are the depleted Jabiru oil field, where oil was produced from the Jurassic Montara Formation, and the Cash/Maple accumulation, hosted in the Challis, Plover and Montara formations. In addition, numerous wells recording oil and gas shows in the Nome, Plover and upper Vulcan Formations (e.g. Pengana 1, Octavius 2 and Tenacious wells respectively; Figure 2) are found in the immediate vicinity of Release Area AC15-1.

Release Area AC15-2 presents both Vulcan Sub-basin (as for AC15-1) and Londonderry High play opportunities (Figure 3). The Londonderry High is characterised by highly faulted Paleozoic and Triassic rocks, which acted as a major source of sediment for adjacent depocentres during Late Jurassic rifting. The Triassic section is unconformably overlain by a relatively unfaulted Upper Jurassic and younger succession. Although most faulting terminates at the top of the Triassic succession, some faults show evidence of Miocene reactivation. Following uplift during the Late Triassic Fitzroy Movement the Triassic section was deeply eroded in places. Potential gas reservoirs in Release Area AC15-2 include the upper Vulcan Formation (Delamere accumulation) and carbonates of the Hyland Bay Subgroup (Osprey 1). Potential oil reservoirs include the Triassic Challis Formation (Challis accumulation), Puffin Formation (Challis 7, Puffin accumulation) and Paleocene Johnson Formation carbonates (Snowmass 1), although intraformational seals are required. The most recently drilled wells on the western flank of the Londonderry High are within 12 km of Release Area AC15-2 and were all drilled by PTTEP. They include Clairault 1 (2009), Ironstone 1 (2011) and Kingtree 1 (2011). Clairault 1 tested targets within the Triassic Pollard Formation and Berriasian upper Vulcan Formation.

Petroleum systems elements

Vulcan Sub-basin

Sources
  • Middle–Upper Jurassic transgressive marine shales of the Montara and lower Vulcan formations
  • Lower–Middle Jurassic fluvio-deltaic Plover Formation
  • Permo-Triassic marine-deltaic shales of the Kinmore Group including the Fossil Head and Ascalon formations
Reservoirs
  • Upper Cretaceous submarine fan sandstones of the Puffin Formation
  • Upper Jurassic–Lower Cretaceous submarine fan sandstones of the Vulcan Formation
  • Middle–Upper Jurassic marine shoreface/barrier bar sandstones of the Montara Formation
  • Lower–Upper Jurassic fluvio-deltaic Plover Formation
  • Upper Triassic estuarine to intertidal Challis Formation and deltaic Nome Formation and equivalents
  • Paleogene carbonates of the Oliver Sandstone Member, Oliver Formation and Cartier Formation (Woodbine Group)
Seals Regional seals
  • Paleocene marine carbonates of the Johnson Formation
  • Lower Cretaceous marine claystones of the Echuca Shoals and Jamieson formations
  • Upper Jurassic–Lower Cretaceous marine claystones of the Vulcan Formation

Intraformational seals

  • Paleogene–Neogene Woodbine Group carbonates
Traps
  • Stratigraphic traps including submarine fan sandstones, reefs, pinchouts and unconformities
  • Structural traps consisting of tilted fault blocks, horst blocks and anticlines

Infrastructure

Release Areas AC15-1 and AC15-2 are proximal to the Cash/Maple gas accumulation currently being planned for development by PTTEP. The nearest fixed infrastructure are the Montara platform 120 km to the southwest, and the Ichthys pipeline which is under construction approximately 100 km to the southeast. In the past, production of oil fields in the Vulcan Sub-basin has been through the use of floating, production, storage and offtake (FPSO) vessels. The port of Darwin is approximately 600 km from the Release Areas.

Critical risks

Structural complexity in the Vulcan Sub-basin has meant adequately imaging reservoir, trap and seals has historically proven challenging. Acquisition of 3D seismic data and the re-processing of existing seismic could assist with the re‑evaluation of Release Areas AC15-1 and AC15-2 and post-drill analysis of nearby discovery wells.

Repeated episodes of fault reactivation (particularly during the Neogene) and associated, remigration, water washing, and gas flushing have locally degraded oil accumulations in ‘leaky traps’ such as Jabiru. The risk of water washing degrading oil accumulations in AC15-1 is difficult to determine as water washing in the area is highly variable. For example – Jabiru and Tenacious oils to the south and west of the Release Area respectively show moderate water washing, Audacious 1 oil shows significant water washing, and Oliver 1 oils show no evidence of water washing. The Delamere 1 gas accumulation in Release Area AC15-2 is biodegraded. While remobilised Siluro–Ordovican evaporites as seen at Paqualin 1 are less extensive in the Vulcan Sub-basin than in other parts of the Bonaparte Basin, there is a risk that localised salt intrusions could impact on seal integrity. Elevated geothermal gradients during the Middle Jurassic as modelled in Jabiru 1 may affect the timing of hydrocarbon generation and expulsion in the Vulcan Sub-basin and adversely affect reservoir quality.

Recent drilling in and around Release Area AC15-2 has progressively improved knowledge of trap and seal mechanisms, and source and reservoir potential in this relatively under explored part of the Vulcan Sub-basin (Figure 4). Erosion on the Londonderry High has restricted the areal extent of reservoir and seal units and reduced the likelihood of widespread Jurassic reservoirs and source rocks in the eastern part of Release Area AC15-2. Migration pathways for hydrocarbons sourced in the Swan Graben up onto the eastern flank of the Vulcan Sub-basin and Londonderry High are at the proven limit of migration. Hence, a lack of a Jurassic charge is a risk for plays in Release Area AC15-2. However, it is possible that mature Permian source rocks could provide an alternative hydrocarbon charge for Triassic reservoirs on the Londonderry High.

Datasets

Wells Data and Seismic Survey listings for the Vulcan Sub-basin are available in the Supporting Information section.

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AHMAD, M. AND MUNSON, T.J., 2013—Chapter 36: Bonaparte Basin. In: Ahmad, M. and Munson, T.J. (compilers), Geology and mineral resources of the Northern Territory, Northern Territory Geological Survey, Special Publication 5.

BAXTER, K., COOPER, G.T., HILL, K.C. AND O'BRIEN, G.W., 1999—Late Jurassic subsidence and passive margin evolution in the Vulcan Sub-basin, north-west Australia; constraints from basin modelling. Basin Research, 11, 97–111.

BEARDSMORE, G.R. AND O’SULLIVAN, P.B., 1995—Uplift and erosion on the Ashmore Platform, North West Shelf; conflicting evidence from maturation indicators. The APEA Journal, 35(1), 333–343.

BOTTEN, P.R., ROSSER, J. AND GORTER, J., 1992—Comparisons in the structural and stratigraphic evolution of the Vulcan Graben and basins in the eastern Timor Sea and ramifications for hydrocarbon exploration. Annual Meeting Abstracts - American Association of Petroleum Geologists and Society of Economic Paleontologists and Mineralogists 1992, 11–12.

BOURDET, J., EADINGTON, P., VOLK, H., GEORGE, S.C., PIRONON, J. AND KEMPTON, R., 2012—Chemical changes of fluid inclusion oil trapped during the evolution of an oil reservoir; Jabiru-1A case study (Timor Sea, Australia). Marine and Petroleum Geology, 36, 118–139.

BOURNE, J.D. AND FAEHRMANN, P.A., 1991—The Talbot Oilfield, Vulcan Sub-basin, Timor Sea; a Triassic oil discovery. The APEA Journal, 31, 42–54.

CHEN, G., HILL, K.C. AND HOFFMAN, N., 2002—3D structural analysis of hydrocarbon migration in the Vulcan Sub‑basin, Timor Sea In: Keep, M. and Moss, S.J. (eds), 2002, The Sedimentary Basins of Western Australia 3: Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, WA, 2002, 377–388.

DAWSON, D., GRICE, K., ALEXANDER, R. AND EDWARDS, D., 2007—The effect of source and maturity on the stable isotopic compositions of individual hydrocarbons in sediments and crude oils from the Vulcan Sub-basin, Timor Sea, Northern Australia. Organic Geochemistry, 38, 1015–1038.

DUDDY, I.R., GREEN, P.F., GIBSON, H.J., AND HEGARTY, K.A., 2004—Regional palaeo-thermal episodes in northern Australia. In: Ellis, G.K., Baillie, P.W. and Munson, T.J. (eds), Timor Sea Petroleum Geoscience, Proceedings of the Timor Sea Symposium, Darwin, 19–20 June 2003. Northern Territory Geological Survey, Special Publication 1, 2004, 567–591.

EDWARDS, D.S., PRESTON, J.C., KENNARD, J.M., BOREHAM, C.J., VAN AARSSEN, B.G.K., SUMMONS, R.E. AND ZUMBERGE, J.E., 2004—Geochemical characteristics of hydrocarbons from the Vulcan Sub-basin, western Bonaparte Basin, Australia. In: Ellis, G.K., Baillie, P.W. and Munson, T.J. (eds). Timor Sea Petroleum Geoscience, Proceedings of the Timor Sea Symposium, Darwin, 19–20 June 2003. Northern Territory Geological Survey, Special Publication, 1, 169–201.

FUJII, T., O’BRIEN, G.W., TINGATE, P. AND CHEN, G., 2004—Using 2D and 3D basin modelling to investigate controls on hydrocarbon migration and accumulation in the Vulcan Sub-basin, Timor Sea, northwestern Australia. The APPEA Journal, 44(1), 93–122.

GEORGE, S.C., LISK, M., EADINGTON, P.J., KRIEGER, F.W., QUEZADA, R.A., GREENWOOD, P.F. AND WILSON, M.A., 1997—Fluid inclusion record of early oil preserved at Jabiru Field, Vulcan Sub-basin. Exploration Geophysics, 28, 66–71.

GRADSTEIN, F.M., OGG, J.G. SCHMITZ, M.D. AND OGG, G.M. (EDITORS), 2012—The Geologic Time Scale 2012; Volumes 1 and 2. Elsevier BV, 1144pp.

HIGGINS, R.I. AND O'BRIEN, G.W., 1998—Fault linkage across the Yampi Shelf-Vulcan Graben transition, Timor Sea. Geological Society of Australia Abstracts, 49, 210.

HILL, K.C., O'BRIEN, G.W., COOPER, G.T. AND GANG, C., 1999—2D and 3D structural restoration, trap integrity, and fluid migration in the Vulcan Sub-basin, Timor Sea, Australia. The APPEA Journal, 39(1), 725.

HILLIS, R.R., MILDREN, S.D., PIGRAM, C.J. AND WILLOUGHBY, D.R., 1997—Rotation of horizontal stresses in the Australian North West continental shelf due to the collision of the Indo-Australian and Eurasian plates. Tectonics 16, 323–335.

KENNARD, J.M., DEIGHTON, I., EDWARDS, D.S., COLWELL, J.B., O'BRIEN, G.W. AND BOREHAM, C.J., 1999—Thermal history modelling and transient heat pulses: new insights into hydrocarbon expulsion and "hot flushes" in the Vulcan Sub-Basin, Timor Sea. The APPEA Journal, 39(1), 177–207.

KIVIOR, T., KALDI, J.G. AND LANG, S.C., 2002—Seal potential in Cretaceous and Late Jurassic rocks of the Vulcan Sub-basin, North West Shelf, Australia. The APPEA Journal, 42(1), 203–224.

LISK, M., BRINCAT, M.P., EADINGTON, P.J. AND O'BRIEN, G.W., 1998—Hydrocarbon charge in the Vulcan Sub‑basin. In: Purcell P.G. & Purcell R.R. (eds). The Sedimentary Basins of Western Australia 2, Petroleum Exploration Society of Australia, Perth, 287–303.

LIU, K., FENTON, S., BASTOW, T., VAN AARSSEN, B. AND EADINGTON, P., 2005—Geochemical evidence of multiple hydrocarbon charges and long distance oil migration in the Vulcan Sub-basin, Timor Sea. The APPEA Journal, 45(1), 493–509.

LORENZO, J.M., TANDON, K. & BOEHNE, R., 1994—Pliocene flexural extension over the Vulcan Sub-basin (Timor Sea, North West Shelf, Australia); observations and elastic modeling. Eos, Transactions, American Geophysical Union, 75, 332.

MILDREN, S.D., HILLIS, R.R., KIVIOR, T. AND KALDI, J.G., 2004—Integrated seal assessment and geologic risk with application to the Skua Field, Timor Sea, Australia. In: Ellis, G.K., Baillie, P.W. and Munson, T.J. (eds), Timor Sea Petroleum Geoscience, Proceedings of the Timor Sea Symposium, Darwin, Northern Territory, 19–20 June 2003, Northern Territory Geological Survey, Special Publication, 1, 275–294.

MORY, A.J., 1991—Geology of the Offshore Bonaparte Basin, Northwestern Australia. Geological Survey of Western Australia Report 29, 47pp.

O’BRIEN, G.W., LISK, M., DUDDY, I.R., HAMILTON, J., WOODS, P. AND COWLEY, R., 1999—Plate convergence, foreland development and fault reactivation: primary controls on brine migration, thermal histories and trap breach in the Timor Sea, Australia. Marine and Petroleum Geology, 16, 533–560.

O’BRIEN, G.W., COWLEY, R., LAWRENCE, G., WILLIAMS, A.K., EDWARDS, D. AND BURNS, S., 2003—Margin to prospect scale controls on fluid flow within the Mesozoic and Tertiary sequences, offshore Bonaparte and northern Browse Basins, north-western Australia. In: Ellis, G.K., Baillie, P.W. and Munson, T.J. (eds), Timor Sea Petroleum Geoscience: Proceedings of the Timor Sea Symposium, Darwin, Northern Territory, 19–20 June 2003. Northern Territory Geological Survey, Special Publication, 1, 1–26.

PATTILLO, J. AND NICHOLLS, P.J., 1990—A tectonostratigraphic framework for the Vulcan Graben, Timor Sea Region. The APEA Journal, 30(1), 27–51.

PERESSON, H., WOODS, E.P. AND FINK, P., 2004—Fault architecture along the southeastern margin of the Cartier Trough, Vulcan Sub-basin, North West Shelf, Australia; implications for hydrocarbon exploration. In: Ellis, G.K., Baillie, P.W. and Munson, T.J. (eds), Timor Sea Petroleum Geoscience: Proceedings of the Timor Sea Symposium, Darwin, Northern Territory, 19–20 June 2003. Northern Territory Geological Survey, Special Publication, 1, 156–167.

PETKOVIC, P., COLLINS, C.D.N. AND FINLAYSON, D.M., 2000—Crustal structure across the Vulcan Sub-basin from seismic refraction and gravity data. Exploration Geophysics, 31, 287–294.

SMITH, P.M., 1991—Discovery of salt in the Vulcan Graben; a geophysical and geological evaluation. The APEA Journal, 31(1), 229–243.

TOPHAM, B.D., LIU, K. AND EADINGTON, P.J., 2003—Relationships between V-shale, petrographic character and petrophysical data from the Jurassic reservoir sandstones in the southern Vulcan Sub-basin. Petrophysics, 44, 36–47.

WANG, Z.X., ZHU, G.H., PANG, L.A. AND TANG, W.L., 2012—An oil and gas resource assessment of the Bonaparte Basin, northwest shelf of Australia. Bulletin of Canadian Petroleum Geology, 60(3), 218–226.

WELLMAN, P. AND O'BRIEN, G.W., 1991—Vulcan Graben, Timor Sea; regional structure from a magnetic survey. Geological Society of Australia Abstracts, 30, 87–88.

WOODS, E.P., 2004—Twenty years of Vulcan Sub-basin exploration since Jabiru; what lessons have been learnt? In: Ellis, G.K., Baillie, P.W. and Munson, T.J. (eds), Timor Sea petroleum geoscience; proceedings of the Timor Sea symposium, Darwin, Northern Territory, 2003 Northern Territory Geological Survey, Special Publication, 1, 88–93.

WOODS, E.P. AND MAXWELL, A.J., 2004—The significance of the Tenacious oil discovery, Vulcan Sub-basin, Australia. In: Ellis, G.K., Baillie, P.W. and Munson, T.J. (eds). Timor Sea petroleum geoscience; proceedings of the Timor Sea symposium, Darwin, Northern Territory, 2003 Northern Territory Geological Survey, Special Publication, 1, 471–482.

WORMALD, G.B., 1988—The geology of the Challis oilfield - Timor Sea, Australia. The North West Shelf, Australia. In: Purcell, P.G. and Purcell, R.R. (eds), Proceedings of the North West Shelf Symposium, Perth, Western Australia, 10–12 August, 1988, Petroleum Exploration Society of Australia, Perth, 425–437.

YASSIR, N. AND OTTO, C.J., 1997—Hydrodynamics and fault seal assessment in the Vulcan Sub-basin, Timor Sea. The APPEA Journal, 37(1), 380–389.

Figures

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Figure 1

 Bonaparte Basin-Vulcan Sub-basin-figure-1 map image
Structural elements of the Vulcan Sub-basin and Londonderry High showing petroleum fields and discoveries, the 2014 and 2015 Release Areas, and the location of the seismic line (Figure 3)
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Figure 2

 Bonaparte Basin-Vulcan Sub-basin-figure-2 map image
Stratigraphy and hydrocarbon discoveries of the Vulcan Sub-basin and Londonderry High based on the Bonaparte Basin Biozonation and Stratigraphy Chart 34 (Kelman et al, 2014). Geologic Time Scale after Gradstein et al (2012)
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Figure 3

 Bonaparte Basin-Vulcan Sub-basin-figure-3 map image
Seismic line VTT/17 across the Vulcan Sub-basin and Londonderry High. Interpretation after AGSO (1996). Location of the seismic line is shown in Figure 1
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Figure 4

 Bonaparte Basin-Vulcan Sub-basin-figure-4 map
Seismic and well data in the vicinity of Release Areas AC15-1 and AC15-2 in the Vulcan Sub-basin and on the Londonderry High, Bonaparte Basin
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