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COOPER BASIN Links Tenements (link to the PIRSA website for the latest information) Acreage release results, 1998–2009 Reports • The petroleum geology of South Australia, Volume 4: Cooper Basin (Gravestock et al., 1998; PDF) • Economics of gas gathering and processing in the Cooper Basin (McDonough, R., 1997; PDF) • Associated cash flow spreadsheet (Excel) • Cooper Basin fact sheet (Petroleum and Geothermal Group, 2008) Publications (website, PIRSA) Acreage releases, previous (website, PIRSA) Summary Age Late Carboniferous – Middle Triassic. 2 Area in South Australia 35 000 km (13 510 sq. miles). Depth to target zones 1250–3670 m. Thickness 2500 m. Hydrocarbon shows Widespread over 8 formations. First commercial discovery 1963 gas (Gidgealpa 2). 3 Production (12 months to June 2004) 3.283 Gm sales gas, 227.8 kt LPG, 332.06 ML condensate, 384.21 ML crude oil, 20.42 kt ethane (Cooper and Eromanga basins). Basin type Intracratonic. Depositional setting Non-marine. Reservoirs Fluvial, deltaic, shoreface sandstones. Regional structure Faulted anticlines. Seals Lacustrine shale, coal. Source rocks Carbonaceous shale, thick (up to 30 m) coal. Depth to oil/gas window 1250 m. Number of wells ~1800. 2 Seismic line km 75 633 2D; 8830 km 3D (58 827 km) 1 Cooper Basin Structural setting The intracratonic Cooper Basin represents a Late Carboniferous to Triassic depositional episode terminated at the end of the Middle Triassic with widespread compressional folding, regional uplift and erosion. It lies unconformably over early Palaeozoic sediments of the Warburton Basin and is overlain disconformably by the central Eromanga Basin. In the northern Patchawarra Trough, the Cooper Basin is locally overlain by the 2 2 Late Triassic Cuddapan Formation. Total area exceeds 130 000 km , of which ~35 000 km are in NE South Australia. Three major troughs (Patchawarra, Nappamerri and Tenappera) are separated by structural ridges (Gidgealpa–Merrimelia–Innamincka (GMI) and Murteree) associated with the reactivation of NW-directed thrust faults in the underlying Warburton Basin (Figs 1, 2). The major tectonic episode separating the Cooper and Warburton basins is interpreted to be the Devonian–Carboniferous Alice Springs Orogeny. Three troughs contain up to 2500 m of Permo-Carboniferous to Triassic sedimentary fill overlain by as much as 1300 m of Jurassic to Tertiary cover. The basin contains a number of non-marine depositional sequences within the Late Carboniferous to Late Permian Gidgealpa Group and Late Permian to Middle Triassic Nappamerri Group. Exploration history Petroleum exploration commenced in 1954 with the granting of an exploration licence to Santos. Exploration commenced in 1959 with the drilling of Innamincka 1 following a reflection–refraction survey carried out over the Innamincka Dome with Delhi Petroleum as operator. Additional reflection surveys over the ensuing years led to the discovery of gas in Gidgealpa 2 in 1963 (Fig. 3). Since then, over 1500 wells have been drilled and more than 80 000 km of seismic have been recorded (Figs 4, 5). PIRSA held three releases of former PELs 5 and 6 acreage between 1998 and 2000, with a total of 27 new petroleum exploration licences offered. In November 2001 the first of the new licences were granted to the successful bidders in the CO98 acreage release following signing of a historic native title agreement. Access agreements were completed in 2002–03 for the CO99 and CO2000 acreage release areas. A vigorous new phase of exploration commenced in 2002 and exploration drilling activity is peaking in 2006-07. Stratigraphy The Cooper Basin unconformably overlies flat lying to compressively deformed Cambro-Ordovician Warburton Basin strata and Carboniferous granitic intrusives. The unconformity is mapped as the Z seismic horizon . The oldest units are the Late Carboniferous to Early Permian Merrimelia Formation and Tirrawarra Sandstone which comprise terminoglacial and glaciofluvial systems deposited unconformably on a glacially scoured landscape (Fig. 6). The Tirrawarra Sandstone represents braided fluvial to fan-delta deposits overlain by peat swamp and floodplain facies of the Patchawarra Formation. Locally (e.g. Pondrinie Field), Merrimelia aeolianite forms a major gas reservoir. Two lacustrine shale units (Murteree and Roseneath shales) with intervening fluviodeltaic sediments (Epsilon and Daralingie formations) were deposited during a phase of continued subsidence. Early Permian uplift led to erosion of the Daralingie Formation and underlying units from basement highs. The Late Permian Toolachee Formation (Fig. 7) was deposited on the Daralingie unconformity surface and is overlain conformably by Late Permian to Middle Triassic Arrabury Formation (comprising the Callamurra, Paning and Wimma Sandstone members) and the Middle to early Late Triassic Tinchoo Formation. Source rocks Permian coal measures and shales are the principal hydrocarbon source rocks in the region and are dominated by Type III kerogens derived from higher plant assemblages. Oils and condensates are typically Petroleum and geothermal in South Australia 2 Cooper Basin o medium to light (30–60 API) and paraffinic, with low to high wax contents. Most Permian oils in Permian reservoirs contain significant dissolved gas and show no evidence of water washing. Gas composition is closely related to maturity/depth with drier gas occurring towards basin depocentres although there is strong geological control on hydrocarbon composition. The Patchawarra Trough contains the bulk of the oil and wet gas reserves consistent with local source rocks being in the ‘oil window’, while the hot Nappamerri Trough (40–50 ºC/km), underlain in part by granite, is over mature and contains mainly dry gas. Permian source rocks have average TOC and S2 pyrolysis yields of 3.9% and 6.9 kg/t, respectively (excluding coals). Locally, the Toolachee Formation is the richest source unit. The Patchawarra Formation is considered the other major source unit, especially the lower shales and coals. The lacustrine Murteree and Roseneath shales have little source potential. Together, the petrographic and geochemical evidence support coals and associated dispersed organic matter as the effective source rocks capable of generating gas and minor oil, albeit in low yields. At maturity levels between 0.7–0.95% Ro, initial generation from the richer facies has led to partial filling of reservoirs with wet gas and oil. There is a sharp onset of significant hydrocarbon accumulation when the source reaches a maturity of 0.95% Ro. Thin, laterally discontinuous coals represent the best source rocks of the upper Nappamerri Group, whilst shales tend to be organically lean. The lower Nappamerri Group is coal-poor, contains kerogen that tends to be oxidised, and any source rocks are humic-rich and gas-prone. Reservoirs and seals Multi-zone high-sinuosity fluvial sandstones form poor to good quality reservoirs. The main gas reservoirs occur primarily within the Patchawarra Formation (porosities up to 23.8%, average 10.5%; permeability up to 2500 mD) and Toolachee Formation (porosities up to 25.3%, average 12.4%; permeability up to 1995 mD). Shoreface and delta distributary sands of the Epsilon and Daralingie formations are also important reservoirs. Oil is produced principally from low-sinuosity fluvial sands within the Tirrawarra Sandstone (porosities up to 18.8%, average 11.1%; permeability up to 329 mD). Towards the margin of the Cooper Basin, oil is also produced from the Patchawarra Formation and from fluvial channel sands in the Merrimelia Formation in Malgoona Field. The Callamurra Member of the Arrabury Formation is conventionally regarded as a regional seal, but nevertheless contains economic oil and gas reservoirs in some areas and is a leaky seal in others. Low- sinuosity fluvial sandstones of the Paning and Wimma Sandstone members form economic oil and gas reservoirs, and high-sinuosity fluvial sandstone of the Tinchoo Formation reservoirs oil. As yet, there have been no economic oil or gasfields discovered in the Cuddapan Formation in South Australia. Intraformational shale and coal form local seals in the major reservoir units. Beneath the Daralingie unconformity are two important early Permian regional seals — the Roseneath and Murteree shales. The Roseneath Shale is the top seal of the Epsilon Formation, and the Murteree Shale seals the Patchawarra Formation. A younger regional seal is provided by the Triassic Arrabury Formation. Traps Where the regional seal is thin or absent, multiple oil and gas pools are stacked in coaxial Permian– Mesozoic structures and may occur from as low as the Patchawarra Formation to as high as the Murta Formation (Fig. 8). Locally, Permian oil has migrated into Warburton Basin reservoirs on the basin margin and gas has migrated into fractured Ordovician reservoirs fringing the Allunga Trough. Petroleum and geothermal in South Australia 3 Cooper Basin Anticlinal and faulted anticlinal traps have been relied on as proven exploration targets but potential remains high for discoveries in stratigraphic and sub-unconformity traps, especially where the Permian sediments are truncated by the overlying Eromanga Basin succession. Economic oil and gas are reservoired in the Nappamerri Group, paradoxically regarded as a regional seal to the Cooper Basin. Prospectivity and undiscovered resources The Cooper Basin is a mature petroleum province, however potential remains high for discoveries in stratigraphic and sub-unconformity traps, which have received increasing interest in the past five years. Pinchout plays along the margins of the Cooper Basin have been tested with commercial success. 3D seismic is playing a critical role in delineating more subtle traps in the future. Current projects A new project to evaluate the coal seam methane potential of the Cooper and Eromanga Basins commenced in April 2009. Exploration access The Innamincka and Strzelecki regional reserves occur over the Cooper Basin (Fig. 9). Exploration and production are permitted. Within the Innamincka Regional Reserve a special management zone exists that excludes access for petroleum activities. At the core of this zone is the Coongie Lakes National Park. Other conditional access zones exist around the Coongie Lakes area limiting access for petroleum or mineral exploration or production. Much of the current petroleum produced from the Cooper Basin originates from within the Innamincka Regional Reserve. Parts of the Cooper Basin are listed as wetlands of international significance under the Ramsar Convention (the 1971 Convention on Wetlands of International Importance). The Coongie Lakes and part of the Coopers Creek system have also been included in the Register of the National Estate (Fig. 9). The initial 2001 right to negotiate (RTN) agreements in the Cooper Basin for the CO-98 PEL application areas were groundbreaking in Australia as the first conjunctive agreements (covering exploration and production) that provide certainty in enabling any explorer, the Aboriginal parties, and the state being able to benefit from any commercial discoveries made. Further agreements were settled for the CO-99 and CO- 2000 acreage releases in 2002, and in July 2005 for the CO2003 release adjacent to the Coongie Lakes region. The most recent agreement was concluded in August 2007 for the CO2005 release block in the Nappamerri Trough. These agreements establish processes to protect Aboriginal heritage before and during field operations, and to provide payments for the interference with the enjoyment of the native title rights of the claimants. All of these agreements are conjunctive, and cover all petroleum licence activities from exploration through to development and production. 2 Compulsory relinquishment of roughly 36% (19 150 km ) of the areas in current Cooper region PELs will precede competitive bidding from 2009. In anticipation of the calling for work program bids in 2009, negotiations opened in 2006 to develop a conjunctive Indigenous land access agreement (ILUA) for the regions already covered with land access agreements resulting from earlier RTN proceedings. These negotiations involve the Aboriginal Legal Rights Movement, the three native title parties already familiar with the RTN process, the South Australian Government, and petroleum exploration and production company representatives (through the South Australian Chamber of Mines and Energy). The draft framework agreement established in 2006 will be the subject of necessary formal negotiations as required by the Native Title Act 1993, with a hope to formalise ILUAs for the whole of the Cooper Basin region in 2007. Petroleum and geothermal in South Australia 4 Cooper Basin The first conjunctive ILUA in Australia in a proven petroleum province was concluded in February 2007 with the Yandruwandha–Yawarrawarrka native title claimants over a major portion of the South Australian Cooper Basin. This will provide greater certainty and expedite the grant of PELs in a way that remains fair to native title claimants and sustainable in relation to exploration and production investment. The application of conjunctive ILUAs will enable land access more quickly and with lower transaction costs than serial RTN proceedings. The successful implementation of conjunctive ILUAs for Cooper Basin petroleum exploration and production will serve as a model for analogous agreements elsewhere in the state. Negotiations in respect to formalising conjunctive petroleum ILUAs with the remaining two native title claimant parties in the Cooper Basin are progressing. In summary, conjunctive ILUAs are proposed as an evolutionary, additional, alternative to the RTN process already working comparatively well in South Australia. Indeed, conjunctive ILUAs will be an attractive incentive to achieve competitive bids, with explorers knowing the terms of land access prior to lodging bids. Licence status Licence activity in the previous year is discussed in the ‘Exploration and development’ section of this DVD and Figure 10 shows the licence status at the time of publication. Use this link for further information on holders of petroleum tenements in South Australia. Key references Altmann, M.J. and Gordon, H.M., 2004. Oil on the Patchawarra Flank - some implications from the Sellicks and Christies oil discoveries. In: Boult, P.J., Johns, D.R. and Lang, S.C. (Eds), PESA’s Eastern Australasian Basin Symposium II, Adelaide 2004. Petroleum Exploration Society of Australia. Special Publication, pp. 29- 34. Boucher, R.K., 2001a. Warburton Basin GIS data atlas. South Australia. Department of Primary Industries and Resources. Report Book, 2001/019. Use this link to read about this atlas or order a free copy. Boucher, R.K., 2001b. Analysis of seals of the Roseneath and Murteree Shales, Cooper Basin, South Australia. South Australia. Department of Primary Industries and Resources. Report Book, 2001/015. Flottmann, T., Campagna, D.J., Hillis R. and Warner, D., 2004. Horizontal microfractures and core discing in sandstone reservoirs, Cooper Basin, Australia. In: Boult, P.J., Johns, D.R. and Lang, S.C. (Eds), PESA’s Eastern Australasian Basin Symposium II, Adelaide 2004. Petroleum Exploration Society of Australia. Special Publication, pp. 689-694. Gravestock, D.I., Hibburt, J.E. and Drexel, J.F. (Eds), 1998. The petroleum geology of South Australia. Volume 4: Cooper Basin. South Australia. Department of Primary Industries and Resources. Petroleum Geology of South Australia Series. Kramer, L., McKirdy, D.M., Arouri, K.R., Schwark, L. and Leythaeuser, D., 2004. Constraints on the hydrocarbon charge history of sandstone reservoirs in the Strzelecki Field, Eromanga Basin, South Australia. In: Boult, P.J., Johns, D.R. and Lang, S.C. (Eds), PESA’s Eastern Australasian Basin Symposium II, Adelaide 2004. Petroleum Exploration Society of Australia. Special Publication, pp. 589-602. Petroleum and geothermal in South Australia 5 Cooper Basin McDonough, R., 1997. Economics of gas gathering and processing in the Cooper Basin. Revised edn. South Australia. Department of Primary Industries and Resources. Report Book, 97/34. McKirdy, D.M., Arouri, K.R. and Kramer, L., 2005. Conditions and effects of hydrocarbon fluid flow in the subsurface of the Cooper and Eromanga Basins. University of Adelaide report on ARC SPIRT Project C39943025 for PIRSA and Santos Ltd. South Australia. Department of Primary Industries and Resources. Report Book, 2005/2. Nakanishi, T. and Lang, S.C., 2002. Constructing a portfolio of stratigraphic traps in fluvial-lacustrine successions, Cooper–Eromanga Basin. APPEA Journal, 42(1): 65-82. O’Neil, B.J. (Ed.), 1989. The Cooper and Eromanga Basins, Australia. Proceedings of the Cooper and Eromanga Basins Conference, Adelaide, 1989. Petroleum Exploration Society of Australia, Society of Petroleum Engineers, Australian Society of Exploration Geophysicists (SA Branches). Underschultz, J. and Boult, P., 2004. Top seal and reservoir continuity: hydrodynamic evaluation of the Hutton-Birkhead Reservoir, Gidgealpa Oilfield. In: Boult, P.J., Johns, D.R. and Lang, S.C. (Eds), PESA’s Eastern Australasian Basin Symposium II, Adelaide 2004. Petroleum Exploration Society of Australia. Special Publication, pp. 473-482. Petroleum and geothermal in South Australia 6 Cooper Basin FIGURES 1. Structural elements on top Warburton Basin. (203838_044) 2. Seismic cross-section, Cooper Basin area, South Australia. C, P and Z seismic horizons. (203838_045) 3. Oil and gas fields. (203838_004) 4. Petroleum and geothermal wells. (203838_046) 5. Seismic lines. (203838_047) 6. Geological summary of the Cooper Basin. (203838_048) 7. Near top of Toolachee Formation (late Permian ‘P’ Horizon) depth structure map. (203838_049) 8. Schematic section showing typical petroleum traps in the Warburton, Cooper and Eromanga basins. (203838_050) 9. Parks, reserves and environmental sites. (203838_051) 10. Petroleum and geothermal tenements. (203838_052) Petroleum and geothermal in South Australia 7 139°0'E 140°0'E 141°0'E QUEENSLAND 500000 26°0'S Cooper Basin GE subcrop limit T RID EN Moomba YM IE " BA OW M JA E RI ME TH DG S UN W E SOUTH AUSTRALIA O MO DD HA AR TR RAB O U UR GH Y " ADELAIDE Eromanga Basin 27°0'S 27°0'S E DG RI K 7000000 7000000 AC TR LE IL CANDRA SV RIDGE RD BI KA LE NC MI E H D G Warburton Basin D NA IDG U SA GE IN R O TR K C R ID Cooper PA A R AR IA EL AW IM E H R G Innamincka TC ER ID PA " M R H Basin RO UG T R I ER AM E A DG LP PP 28°0'S NA RI EA 28°0'S A- EE DG LL N G DECOO E GI Moomba A DG PP RI NA " RA G H W RO AR E OU W IDG T O U TR O G R LO H A NG O PA TOOLACHEE LU R NO AL MENT ID O RIDGE EMBAYTIKA G E GH LA OU KA E E MET R E TR ER N T BO PR DI IDG OO EN DE RT GE RA R UN M XWES MU RID PE D BAY AP O SIO N O N EM TE D KOBARI EMBAYMENT DUNOON RIDGE TINGA MILPERA DEPRESSION RA TINGA PE E 6800000 6800000 IL IDG M R NA 29°0'S 29°0'S RIDG WEEDNA TROUGH E NEW SOUTH WALES 500000 139°0'E 140°0'E 141°0'E 0 25 50 km MGA Zone 54 Cooper Basin South Australia STRUCTURAL ELEMENTS ON TOP WARBURTON BASIN Figure 1 PIRSA 203838_044 0.5 0.5 A A’ 1 1 C Z C 1.5 1.5 P 2 2 Z 2.5 2.5 3 3 B B’ C C’ D D’ C C C C C C P P P P Z P P Z Z Z Z Z E E’ C REGIONAL SEISMIC CROSS SECTION Line of sections are displayed on Plan No 8 C P C HORIZON C C P Z P HORIZON P P Z Z HORIZON Z Z C Seismic Horizon correlates to Top Cadna-owie Formation P Seismic Horizon correlates to Near Top Permian Z Seismic Horizon correlates to Top Warburton Basin 203838_045 Figure 2 Seismic cross-section, Cooper Basin area, South Australia. C, P and Z seismic horizons. 138°0'E 139°0'E 140°0'E 141°0'E 250000 QUEENSLAND 500000 26°0'S 26°0'S Cooper Basin subcrop limit Moomba " SOUTH AUSTRALIA Simpson Basin " ADELAIDE 27°0'S 27°0'S m n Kiwi # * 7000000 7000000 Cleansweep n m Acrasia m n Vanessa Yarrow North m n n m Yarrowm n Flax m n n m Warhawk Juniper Warburton Basin m n Wirraway n m # * Eromanga Basin m n Growler m n Tigercat # * # * n m # * Mudrangie South PL5 PL18 Cadenza # * Chiton # * m n Rossco m n n m Cooper Sellicks Paprika Paranta # * m n Canunda m n n m Callawonga Smegsy Basin n m n m n m Parsons # * n m 28°0'S m n Udacha m n n m Brownlow m n Perlubie m n n m 28°0'S m n m n Silver # * Butlers Sands Middleton # * Christies Moomba " Mudera Kiana m n North # * PL17 n m # * # * # * # * # * PL15 Stimpson Jay n m Teringie Squalo Hornet PL9 Arwon #* Frostillicus Hobbes # Mama Odonata n m * Worrior n m Calvin Derrilyn m n n m m n n m n m n m nn mm Toparoa Granchio n m Stimpee Lightning m n m n m m m n n n m n # * Ragno n m n m n m m n m n m n n m Revenue n m Itchy nn mm Bugito Rissikia Ventura n m n m m n Harpoono Pasticcio Mirage Comic Seccante PLs7,8 n m Might and Power Rimfire Aldinga 6800000 6800000 29°0'S 29°0'S NEW SOUTH WALES PL2 PL1 250000 500000 138°0'E 139°0'E 140°0'E 141°0'E 0 25 50 km MGA Zone 54 Pipeline licence (PL) # * Satellite station Gas pipeline Gas field (new entrant fields named) Gas and liquids pipeline Oil field (new entrant fields named) Cooper and Eromanga basins Liquids pipeline South Australia OIL and GAS FIELDS Figure 3 PIRSA 203838_004 138°0'E 139°0'E 140°0'E 141°0'E NT 250000 QUEENSLAND 500000 26°0'S 26°0'S Cooper Basin . subcrop limit . Moomba . . . . " . . . . Simpson Basin . . . . . " . . . ADELAIDE . . . . 27°0'S . . 27°0'S . . . . . . . 7000000 7000000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Warburton Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eromanga Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PL18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .