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Northern Caswell Sub-basin

Bids close 29 October 2015

  • On trend with the Calliance, Brecknock, Torosa and Crown/Proteus gas fields
  • Close to Ichthys Gas Pipeline to Bladin Point, Darwin (currently under construction)
  • Shallow to deep water depths, 350–500 m
  • Thick Jurassic–Lower Cretaceous mature source rocks
  • Tilted Permo-Triassic and Jurassic fault blocks, and fluvio-deltaic to marine fan sands with Cretaceous seal
  • Special Notices apply, refer to Guidance Notes

Release Area AC15-3 is located in the northern Caswell Sub-basin, approximately 250 km from the northeast coast of Western Australia (Figure 1). The area consists of 26 graticular blocks in waters 350–500 m deep and includes the Phrixus 1 well, which resulted in oil and gas shows from the Bassett and upper Jamieson formations, respectively (Figure 2). The presence of gas in the nearby Abalone 1 and Abalone Deep 1 wells in the Puffin, Gibson, lower  Jamison and Echuca Shoals formations (Figure 2) indicate that an extension of the Calliance, Brecknock, Torosa and Crown/Proteus trend may extend across Release Area AC15-3.

A diverse range of undrilled structures may be prospective in the Release Area. The dominant fault styles in the region are horsts and tilted fault blocks (Figure 3), where potential reservoirs include the Upper Triassic Nome Formation, the Jurassic Plover and Montara formations, the Upper Jurassic–Lower Cretaceous Vulcan and Echuca Shoals formations and, in some locations, the Upper Cretaceous Puffin Formation (Figure 2). 3D seismic data is available across the Release Area, although the region is relatively underexplored compared to the neighbouring Vulcan Sub-basin (Figure 4). Multiple construction activities are in progress in the basin, including Prelude FLNG, the Ichthys LNG Project and gas pipeline, Browse FLNG and Crux.

Petroleum systems elements

Northern Caswell Sub-basin

Sources
  • Lower–Middle Jurassic fluvio-deltaic Plover Formation (oil- and gas-prone)
  • Callovian–Valanginian marine Vulcan and Montara formations (oil-prone), major sediment thickening occurs towards Northern Caswell Release Area
Reservoirs
  • Upper Triassic deltaic Nome Formation
  • Lower–Middle Jurassic fluvio-deltaic Plover Formation
  • Middle–Upper Jurassic marine Montara (Ichthys) and lower Vulcan formations
  • Upper Jurassic–Lower Cretaceous marine upper Vulcan Formation (Brewster Member)
  • Lower Cretaceous Echuca Shoals Formation (shallow marine sandstones and submarine fans)
  • Upper Cretaceous Gibson and Puffin formations (submarine fan sandstones)
Seals Regional Seals
  • Upper Jurassic–Lower Cretaceous marine Vulcan Formation
  • Lower Cretaceous marine Echuca Shoals and Jamieson formations (claystone seal 500–600 m thick across the sub-basin)

Intra-formational seals

  • Lower–Middle Jurassic fluvio-deltaic Plover Formation
  • Upper Cretaceous Puffin Formation and Paleocene Bassett Formation
Traps
  • Jurassic horsts/tilted fault blocks and associated drapes
  • Cretaceous submarine canyon fill, basin floor fans and ‘ponded’ turbidite stratigraphic traps
 

Infrastructure and markets

There are four gas developments at various stages of implementation in the Browse Basin, with two LNG projects in the northern Caswell Sub-basin. The Ichthys gas pipeline is currently under construction and will come within 70 km of the Release Area. First gas from the Ichthys accumulation is planned to come online by 2017. Prelude FLNG, encompassing the Prelude and Concerto accumulations in WA-44-L, is expected to produce LNG in 2016.

Critical risks

Effective migration pathways from adjacent and underlying mature source rocks have been a limitation for some of the wells adjacent to the Release Area. Trap integrity is a risk due to fault reactivation during the late Miocene–Pliocene. The primary cause of failure for the Phrixus 1 well, drilled within the Release Area, was interpreted to be the absence of a sandstone reservoir in the Puffin Formation. However, the presence of gas saturated sandstones within the Puffin Formation in the nearby Abalone 1 well, necessitates the detailed mapping of these fan sandstones within the region.

Data sets

Wells Data and Seismic Survey listings for the northern Caswell Sub-basin are available on the Supporting Information page.

 

Geoscience Australia products

Regional geology and seismic

Stratigraphy

Petroleum systems and accumulations

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BAN, S. AND PITT, G., 2006—The Ichthys giant gas-condensate field. 2006 AAPG International Conference and Exhibition, 5–8 November, Perth, Australia, Abstract.

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BLEVIN, J.E., BOREHAM, C.J., SUMMONS, R.E., STRUCKMEYER, H.I.M. AND LOUTIT, T.S., 1998—An effective Lower Cretaceous petroleum system on the North West Shelf: evidence from the Browse Basin. In: Purcell, P.G. and R.R. (eds), 1998, The Sedimentary Basins of Western Australia 2: Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, WA, 1998, 397–420.

BLEVIN, J.E., STRUCKMEYER, H.I.M., CATHRO, D.L., TOTTERDELL, J.M., BOREHAM, C.J., ROMINE, K.K., LOUTIT, T.S. AND SAYERS, J., 1998—Tectonostratigraphic framework and petroleum systems of the Browse Basin, North West Shelf. In: Purcell, P.G. and R.R. (eds), 1998, The Sedimentary Basins of Western Australia 2: Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, WA, 1998, 369–395.

BRINCAT, M.P., LISK, M., KENNARD, J.M., BAILEY, W.R. AND EADINGTON, P.J., 2004—Evaluating the oil potential of the Caswell Sub-basin; insights from fluid inclusion studies. Special Publication - Northern Territory Geological Survey, 437–455.

EDWARDS, H., CROSBY, J., DAVID, N., LOADER, C. AND WESTLAKE, S., 2005—Australian Megasurveys – the key to new discoveries in maturing areas. The APPEA Journal, 45(1), 407–419.

FUJIMOTO, M., YOSHIDA, T. AND LONG, A., 2010—Improved seismic inversion and reservoir description of Ichthys gas-condensate field, Browse Basin, Western Australia. The APPEA Journal, 50(1) Presentation.

KELMAN, A.P., KENNARD, J.M., NICOLL, R.S., LAURIE, J.R., EDWARDS, D.S., KHIDER, K. AND LE POIDEVIN, S., 2014—Browse Basin Biozonation and Stratigraphy 2014 Chart 32. Geoscience Australia Biozonation and Stratigraphy Chart Series (http://www.ga.gov.au/corporate_data/76687/Chart_32_Browse_Basin_2014.pdf).

KENNARD, J.M., DEIGHTON, I., RYAN, D., EDWARDS, D.S. AND BOREHAM, C.J., 2004—Subsidence and thermal history modelling: new insights into hydrocarbon expulsion from multiple petroleum systems in the Browse Basin. 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, 411–435.

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STRUCKMEYER, H.I.M., BLEVIN, J.E., SAYERS, J., TOTTERDELL, J.M., BAXTER, K. AND CATHRO, D.L., 1998—Structural evolution of the Browse Basin, North West Shelf: new concepts from deep-seismic data. In: Purcell, P.G. and R.R. (eds), 1998, The Sedimentary Basins of Western Australia 2: Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, WA, 1998, 345–367.

SYMONDS, P.A., COLLINS, C.D.N. AND BRADSHAW, J., 1994—Deep structure of the Browse Basin: implications for basin development and petroleum exploration. In: Purcell, P.G. and R.R. (eds), The Sedimentary Basins of Western Australia: Proceedings of Petroleum Exploration Society of Australia Symposium, Perth, 1994, 315–331.

VOLK, H., BRINCAT, M. P., GEORGE, S. C., KENNARD, J. M., EDWARDS, D. S., BOREHAM, C. J., AHMED, M. AND LISK, M., 2005—Clues to fill histories of gas fields in the Caswell Sub-basin; evidence from the distribution and geochemistry of palaeo-oils. The APPEA Journal, 45(1), 679.

WILLIS, I., 1988—Results of exploration, Browse Basin, North West Shelf, Western Australia. In: Purcell, P.G. and R.R. (eds), The North West Shelf, Australia: Proceedings of Petroleum Exploration Society of Australia Symposium, Perth, 1988, 259–272.

Figures

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Figure 1

 Browse Basin-Northern Caswell Sub-basin-figure-1 map image
Structural elements of the Northern Caswell region showing petroleum fields and discoveries, the location of the regional seismic section (Figure 3) and the 2015 and 2014 Release Areas. 2015 Release Areas shown in outline only, are discussed elsewhere.
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Figure 2

 Browse Basin-Northern Caswell Sub-basin-figure-2 map image
Stratigraphy and hydrocarbon discoveries in the Caswell Sub-basin and Brecknock-Scott Reef Trend based on the Browse Basin Biozonation and Stratigraphy Chart 32 (Kelman et al, 2014). Geologic Time Scale after Gradstein et al (2012).
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Figure 3

 Browse Basin-Northern Caswell Sub-basin-figure-3 map image
Seismic line nsw07ph2/32 across the northern Caswell Sub-basin. Seismic line courtesy of PGS. Interpretation by Geoscience Australia. Location of the seismic line is shown in Figure 1.
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Figure 4

 Browse Basin-Northern Caswell Sub-basin-figure-4 map image
Seismic and well data in the vicinity of the Release Area in the northern Caswell Sub-basin, Browse Basin. 2015 Release Areas shown in outline only, are discussed elsewhere.
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