REGIONAL GEOLOGY OF THE NORTHERN CARNARVON BASIN BASIN OUTLINE The Northern Carnarvon Basin is the southernmost of the late Paleozoic to Cenozoic basins that underlie the northwestern continental margin of Australia (Bradshaw et al, 1988). It is bounded to the northeast by the Roebuck and offshore Canning basins, to the southeast by the Pilbara Block, to the south by the Southern Carnarvon Basin, and to the northwest by the Argo, Cuvier and Gascoyne abyssal plains. The basin is predominantly offshore, covering an area of approximately 535,000 km2 in water depths of up to 3,500 m (Figure 1). The sedimentary fill is up to 15 km thick and dominated by deltaic to marine siliciclastics and shelfal carbonates of Mesozoic age. As one of Australia’s most explored and prospective basins, the Northern Carnarvon Basin has ready access to established oil and gas exploration, production and support infrastructure (Figure 2). Major oil and gas production areas are located in the Barrow Island, Varanus and Thevenard areas of the Barrow Sub-basin, the northern parts of the Rankin Platform and Dampier Sub-basin, and the northern Exmouth Sub-basin. Large-scale development projects under way include the Gorgon, Pluto and Wheatstone LNG projects, Macedon–Pyrenees project (gas and oil) and Reindeer–Devils Creek Development (gas). The basin is proximal to the major settlements of Port Hedland, Karratha, Dampier, Onslow, Exmouth and Carnarvon, and the North West Coastal Highway. A major LNG loading terminal and processing centre is located at Karratha. The Dampier to Bunbury Natural Gas Pipeline and the Goldfields Gas Transmission Pipeline provide a direct connection with the major domestic and industrial markets of southern Western Australia (Perth, Bunbury and the Goldfields), and the basin is favourably located in relation to the main export markets in Southeast and East Asia. The offshore Northern Carnarvon Basin consists of three broad structural zones: an inboard, structurally high zone of the Lambert and Peedamullah shelves; an intermediate zone of large depocentres comprising the Exmouth, Barrow, Dampier and Beagle sub-basins; and the extensive, marginal Exmouth Plateau and its uplifted margin, the Rankin Platform (Figure 1). The Argo, Cuvier and Gascoyne abyssal plains bound the distal margins of the Exmouth Plateau and the Exmouth Sub-basin (Figure 1). 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 1 of 22 The geological evolution of the Northern Carnarvon Basin has been discussed in detail by many authors, including Kopsen and McGann (1985), Boote and Kirk (1989), Hocking (1990), Stagg and Colwell (1994), Jablonski (1997), Romine et al (1997), Westphal and Aigner (1997), Driscoll and Karner (1998), Bussell et al (2001), Norvick (2002) and Longley et al (2002). In addition, comprehensive summaries of petroleum geology are presented by Tindale et al (1998) in the Exmouth Sub-basin, Stagg et al (2004) in the Exmouth Plateau, Hearty et al (2002) in the Barrow Sub-basin, Woodside Offshore Petroleum Pty Ltd (1988) and Barber (1994) in the Dampier Sub-basin, and Blevin et al (1994) in the Beagle Sub-basin. Polycyclic extension, culminating in the Jurassic to Early Cretaceous breakup of the northwest Australian continental margin, produced a dominant northeast–southwest structural trend that is apparent in the alignment of major faults and depocentres (Figure 1). A secondary north–south or northnorthwest–south-southeast trend is also apparent, especially in accommodation zones and transfer faults linking northeast-trending en echelon faults. The main structural elements of the Northern Carnarvon Basin (Figure 1) are described briefly below. Representative geologic sections through the basin are shown in Figure 3, Figure 4, Figure 5, Figure 6 and Figure 7. The Exmouth, Barrow and Dampier sub-basins are a series of large en echelon rift depocentres (Figure 1) that contain a dominantly Triassic, Jurassic and Lower Cretaceous sedimentary succession. Maximum sediment thickness exceeds 10 km in the Exmouth and Dampier sub-basins and 15 km in the Barrow Sub-basin (Figure 4 and Figure 5). The Barrow Delta succession dominates the Lower Cretaceous section in the Exmouth and Barrow sub-basins (Tindale et al, 1998). By contrast, fine-grained marine sediments dominate the Upper Jurassic and Lower Cretaceous in the Dampier Sub-basin. The sub-basins themselves comprise a series of en echelon structural highs and troughs with an overall northeast–southwest trend formed by oblique extension. The Beagle Sub-basin comprises a structurally complex series of fault blocks, anticlines and troughs with a general north–south trend, oblique to the regional northeast–southwest trend dominant in the other sub-basins (Figure 1). Lateral fault movements dominated the sub-basin’s evolution with localised areas of extension and compression (Blevin et al, 1994). The sedimentary succession attains a thickness of up to 12 km, and is dominated by Triassic to Middle Jurassic sediments (Figure 6 and Figure 7). In contrast to the other sub-basins, the Upper Jurassic succession is thin or absent. The sub-basins are separated from each other by Paleozoic–Triassic fault blocks that have been modified by faulting, uplift and/or rotation: the Alpha Arch between the Exmouth and Barrow sub-basins, the Sultan Nose between the Barrow and Dampier sub-basins (Polomka and Lemon, 1996), and the De Grey Nose between the Dampier and Beagle sub-basins (Figure 1). 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 2 of 22 The sub-basins are separated from the structurally high areas of the Rankin Platform and Exmouth Plateau to the northwest, and the Lambert and Peedamullah shelves to the east and south, by major extensional fault systems (Figure 1). The Rankin Fault System separates the Rankin Platform from the Dampier Sub-basin (Stagg and Colwell, 1994), and the Flinders and Sholl Island fault systems separate the Peedamullah and Lambert shelves from the Barrow and Dampier sub-basins (Kopsen and McGann, 1985; Figure 1). Broad marginal terraces, overlain by mainly Triassic to Cenozoic sediments, have formed over down-faulted or rotated blocks along these faulted margins. These include the Enderby Terrace in the Dampier Sub-basin (Figure 1 and Figure 5) and the Bruce and North Turtle terraces in the Beagle Sub-basin (Figure 1). These terraces represent major Silurian–Late Permian extensional depocentres that were only moderately affected by the subsequent Mesozoic rifting events, due to a general westward shift in the locus of extension (Hocking, 1990; Polomka and Lemon, 1996). The Exmouth Plateau (Figure 1) is a subsided continental platform characterised by a faulted, dominantly Triassic sedimentary succession attaining a thickness of up to 15 km (Figure 4, Figure 5 and Figure 7). Jurassic sediments are generally thin or absent. The major sub-elements of the plateau include the Rankin Platform, Kangaroo Syncline, Investigator Subbasin and Wombat Plateau (Tindale et al, 1998; Stagg et al, 2004; Figure 1). The dominant structural trend varies between north–south and northeast– southwest, reflecting the interplay between the oblique extensional vectors and the pre-existing structural grain of the basement (Stagg et al, 2004). The Lambert and Peedamullah shelves form the rift shoulders to the Northern Carnarvon Basin (Figure 1). They comprise planated Precambrian cratonic basement mantled by landward-thinning, dominantly Cretaceous–Cenozoic sedimentary rocks up to 2 km thick (Figure 6). In addition, Silurian–Permian successions underlie parts of the Peedamullah Shelf. 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 3 of 22 BASIN EVOLUTION AND TECTONIC DEVELOPMENT The key evolutionary stages of the Northern Carnarvon Basin are (Figure 8): Pre-rift intracontinental basins (Silurian to Toarcian) Early syn-rift (Toarcian to earliest Callovian) Main syn-rift (earliest Callovian to Berriasian) Late syn-rift Barrow Delta (Berriasian to Valanginian) Post-breakup subsidence (Valanginian to mid-Santonian) Passive margin (mid-Santonian to present) Hydrocarbon generation, migration and entrapment in the Northern Carnarvon Basin have been strongly controlled by syn-rift structuring and deposition, and post-rift reactivation. Pre-rift intracontinental basins (Silurian to Toarcian) North–south-trending intracontinental basins developed during the Silurian to Permian in the initial stages of Gondwana breakup. Siliciclastic non-marine to shallow marine sediments deposited during this phase are preserved only in the deeper and southern parts of the basin today (Figure 4, Figure 5, Figure 6 and Figure 7). Northeast–southwest-trending depocentres started to form during the latest Permian. At the beginning of the Triassic, a regional marine transgression deposited the Locker Shale, dominated by marine claystone and siltstone with minor paralic sandstone and shelfal limestone (Figure 8). The Locker Shale grades upwards into the Middle to Upper Triassic Mungaroo Formation (Figure 8). Thick sandstone and claystone with minor coal were deposited by a northwest-prograding fluvio-deltaic system that covered much of the offshore Northern Carnarvon Basin (see the ‘Intra-Triassic’ to ‘Top Triassic’ interval in Figure 4, Figure 5, Figure 6 and Figure 7). The upper Mungaroo Formation consists of shoreline sandstone, shallow marine claystone and minor limestone. In the Beagle Sub-basin, the Middle Triassic Cossigny Member of the Mungaroo Formation (paralic and marine siltstone, claystone and limestone) is a significant regional seismic marker (Figure 8). Fluvial and shoreline sandstone of the Mungaroo Formation host the giant gas accumulations on the Rankin Platform (Figure 9). The Mungaroo Formation is also the main gas-prone source in the Barrow and Dampier sub-basins and the Exmouth Plateau. Deposition throughout the Triassic occurred within broad, gently structured downwarps. The large volume of the Mungaroo Delta suggests that some sediment may have been delivered via transcontinental river systems from 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 4 of 22 central Australia, Argo Land, West Burma, and/or Greater India (Norvick, 2002; Jablonski and Saitta, 2004). Thinly bedded shelfal siltstone, claystone and marl of the Brigadier Formation and Murat Siltstone were deposited in response to rapid subsidence from the latest Triassic to the Early Jurassic (Figure 8). On the Wombat Plateau, uppermost Triassic reef limestone caps the Mungaroo Formation (von Rad et al, 1992a, 1992b). In the outer part of the Northern Carnarvon Basin, the Brigadier Formation is well preserved and is particularly thick in the Kangaroo Syncline in the southern Exmouth Plateau (Bussell et al, 2001). The Brigadier Formation is a significant gas source in the Barrow and Dampier sub-basins and also hosts some accumulations (Figure 9). Thin, reservoir-quality sandstones on some horst blocks along the Rankin Platform are known as the North Rankin Formation (Seggie et al, 2007). In the Beagle Sub-basin, the Late Triassic Fitzroy Movement (Smith et al, 1999) formed a series of structural highs and lows and led to the isolation of the sub-basin from the Dampier Sub-basin (Blevin et al, 1994). Early syn-rift (Toarcian to earliest Callovian) Rifting from the Pliensbachian onward produced the general structural framework of the Northern Carnarvon Basin that is apparent today. Major bounding faults (e.g. the Rosemary, Flinders and Rankin fault systems) developed, delineating the Barrow, Dampier and Exmouth sub-basins, the Rankin Platform, and the Lambert and Peedamullah shelves (Figure 1). An oblique extension vector combined with the pre-existing Proterozoic to Paleozoic north–south structural grain resulted in an en echelon arrangement and compartmentalisation of the sub-basins (Romine et al, 1997). The formation of tilted fault blocks, horsts and graben strongly controlled the pattern of deposition (Barber, 1988). Moreover, the large amount of observed subsidence relative to faulting suggests that lower crustal processes played a major role during crustal extension (Stagg and Colwell, 1994; Driscoll and Karner, 1998; Norvick 2002). The onset of rifting is marked by an unconformity at the JP1 seismic horizon (previously known as the ‘Pliensbachian unconformity’; Figure 8). The Toarcian to earliest Callovian syn-rift megasequence comprises restricted marine claystone and siltstone of the Athol Formation and regressive deltaic sandstone of the Legendre Formation (Figure 8). The Legendre Delta expanded westward from the Beagle Sub-basin into the Dampier Sub-basin and the central Exmouth Plateau by the Bathonian. Sediment was supplied from fault blocks and platforms at the depocentre margins. The Legendre Formation is the likely source for some of the hydrocarbon accumulations in the Dampier Sub-basin (e.g. the Legendre oil field), and hosts gas fields such as Reindeer and Rosemary (Figure 9). Main Syn-rift (earliest Callovian to Berriasian) During the Callovian to Oxfordian, Argo Land separated from Australia and seafloor spreading commenced in the Argo Abyssal Plain (Jablonski, 1997). 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 5 of 22 Uplift and erosion associated with initial extension produced the Callovian unconformity (JC seismic horizon; Figure 8). The main phase of syn-rift deposition in the Northern Carnarvon Basin followed, initially resulting in the transgressive deposition of the Callovian Calypso Formation claystone and sandstone in the Barrow and Dampier sub-basins (Figure 8). Major rift-related faults developed along the northern edge of the Exmouth Plateau. In the late Oxfordian, continental breakup and the onset of seafloor spreading in the Argo Abyssal Plain (Norvick, 2002) resulted in the basal Oxfordian unconformity, or the ‘Breakup Unconformity’ (JO seismic horizon; Figure 8). In places, the basal Oxfordian unconformity corresponds to the so-called ‘Main Unconformity’. However, the latter is a diachronous sequence boundary, of earliest Jurassic to Aptian age (Newman, 1994; Jablonski, 1997). The Main Unconformity is also called the ‘Intra-Jurassic Unconformity’ (Sibley et al, 1999). Continued post-breakup faulting during the Late Jurassic uplifted and tilted the Exmouth Plateau and the Rankin Platform, supplying sediment to adjacent depocentres. Rapid tectonic subsidence resulted in a thick deep marine succession, the Dingo Claystone (Figure 8), which progressively filled, and overlapped the flanks of, the Barrow, Dampier and Exmouth sub-basins (see the ‘Callovian’ to ‘Top Jurassic’ interval in Figure 4 and Figure 5; Tindale et al, 1998). The maximum flooding phase during the Oxfordian provided a favourable depositional environment for high-quality, oil-prone source rocks (Norvick, 2002). At the depocentre margins, reservoir-quality turbidite, submarine fan, shoreline and fluvial sandstones were deposited. Over parts of the Exmouth Plateau, sandy shallow-marine deposition occurred within confined depocentres during the Late Jurassic. The Kangaroo Syncline formed in the southern Exmouth Plateau and northern Exmouth Sub-basin in response to footwall uplift of tilted Triassic fault blocks on the Rankin Platform (Jenkins et al, 2003). Coarse clastic sediments were derived from the erosion of the Mungaroo Formation in uplifted areas and transported into the syncline until the Berriasian (Jenkins et al, 2003). Upper Jurassic sandstones are significant as reservoir formations in parts of the Northern Carnarvon Basin (Figure 9). These include turbiditic sandstone of the Biggada, Eliassen, Dupuy and Angel formations, and shallow-marine to shoreline Jansz and Linda sandstones (Jenkins et al, 2003; Moss et al, 2003; Figure 8). The Angel Formation is the main oil- and gas-bearing reservoir unit in the Dampier Sub-basin, and the Jansz Sandstone hosts the giant Io–Jansz gas accumulation on the Exmouth Plateau (Figure 9). Deposition was terminated during the early Berriasian by another episode of uplift and erosion, marking the onset of rifting between Greater India and Australia. Late Syn-rift Barrow Delta (Berriasian to Valanginian) The late syn-rift phase (Berriasian to Valanginian) was dominated by the extensive Barrow Delta and the resultant deposition of the Barrow Group 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 6 of 22 (Figure 8), which attains a thickness of up to 2.5 km (see the ‘Top Jurassic’ to ‘Valanginian’ interval in Figure 4). Initial deposition occurred over the Exmouth Sub-basin, fed by sediment input from the south. The delta prograded northward to the west of Barrow Island, and across to the Exmouth Plateau, to form the lower Barrow Delta lobe. Approximately 75% of deposition by the Barrow Delta occurred during this phase (Ross and Vail, 1994). The second phase of progradation commenced in the late Berriasian, forming the upper Barrow Delta lobe in the Barrow and Dampier sub-basins 250 km to the east of the delta’s earlier depocentre. The lower Barrow Delta lobe experienced erosion in the shoreward part of the Exmouth Sub-basin as the delta prograded northward to the Gorgon horst. The sediments of the lower (or western) Barrow Delta lobe are collectively known as the Malouet Formation, and those of the upper (or eastern) lobe as the Flacourt Formation. The boundary between the two lobes is markedly diachronous (Baillie and Jacobson, 1997). Dominant facies include basin-floor fan sandstone, pro-delta to foreset claystone, and top-set sandstone. The sandstone at the top of Barrow Group is known in parts as the Zeepaard Formation and Flag Sandstone (Figure 8). The Zeepaard Formation was deposited extensively across the Barrow and Exmouth sub-basins, Rankin Platform and Exmouth Plateau as progradational top-set units of the Barrow Delta in the early Valanginian. In contrast, the Flag Sandstone was deposited as a basin-floor fan in the northeastern Barrow Sub-basin, in front of the delta foresets. Barrow Group sandstones are predominantly quartzose, weakly cemented, and of excellent porosity and permeability in the outer part of the Northern Carnarvon Basin. The Scarborough giant gas accumulation is hosted within a Barrow Group basin-floor fan sandstone (Norvick, 2002; Figure 9). Sediment supply to the Barrow Delta system ceased due to the commencement of continental breakup to the southwest of the Exmouth Plateau during the Valanginian (Hocking, 1990). The Exmouth Sub-basin and Exmouth Plateau were tectonically inverted during breakup, but subsidence and marine sedimentation continued throughout the Barrow and Dampier subbasins. Post-breakup subsidence (Valanginian to mid-Santonian) Continental breakup and the onset of seafloor spreading in the Gascoyne and Cuvier abyssal plains during the Valanginian resulted in widespread peneplanation in the Northern Carnarvon Basin and the formation of the Valanginian unconformity (KV seismic horizon; Figure 8). Rapid subsidence following breakup resulted in a widespread transgression and deposition of a fining-upward marine sequence over the Valanginian unconformity surface (Figure 4, Figure 5, Figure 6 and Figure 7). Localised paralic and shelf deposition formed the Birdrong Sandstone and glauconitic Mardie Greensand, followed by the basin-wide deposition of the transgressive Muderong Shale, Windalia Radiolarite and Gearle Siltstone (Figure 8). The Muderong Shale is a regional seal, but also contains economically important petroleum-bearing glauconitic sandstones such as the 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 7 of 22 M. australis Sandstone (also known as the Stag Sandstone) and Windalia Sandstone in the Barrow and Dampier sub-basins (Figure 8). The Windalia Sandstone has historically been a major exploration target in the Barrow Subbasin (Figure 9). It contains over 90% of the initial oil reserves of the Barrow Island oil field (Ellis et al, 1999). A phase of uplift during the early Santonian in the southern Exmouth Sub-basin formed the Novara Arch (Figure 1) and caused erosion of the Gearle Siltstone (Tindale et al, 1998). Passive Margin (mid-Santonian to present) Siliciclastic sedimentation ceased by the mid-Santonian, as a result of tectonic stability and a decreasing supply of terrigenous sediment. Prograding shelfal carbonate sediments were deposited on the passive continental margin in the Late Cretaceous and Cenozoic (Figure 4, Figure 5, Figure 6 and Figure 7). During the Campanian, uplift of the hinterland resulted in a phase of inversion in the Exmouth Sub-basin and further west, forming the Exmouth Plateau Arch, Resolution Arch and Kangaroo Syncline (Tindale et al, 1998). Preexisting rift-related structures experienced transpressional reactivation within the Barrow and Dampier sub-basins, forming Barrow Island (Longley et al, 2002; Cathro and Karner, 2006). During the Oligocene and Miocene, prograding shelf carbonates (Mandu and Trealla limestones) were deposited (Tindale et al, 1998; Figure 8). In the Miocene, a major compressional event associated with the collision of the Australia–India and Eurasia plates affected the entire northwest Australian margin, including the Northern Carnarvon Basin (Longley et al, 2002). This event caused tilting, inversion and renewed faulting (Malcolm et al, 1991; Cathro and Karner, 2006). This is also the time when many structural traps within the Cretaceous and Cenozoic strata were formed. 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 8 of 22 REGIONAL HYDROCARBON POTENTIAL The Carnarvon Basin is currently Australia’s most prolific hydrocarbonproducing basin; 58.2 MMbbl (9.26 GL) of oil, 1198 Bcf (33.9 Bcm) of gas and 46.6 MMbbl (7.42 GL) of condensate were produced in 2009 (Department of Mines and Petroleum, Western Australia, 2010b). The basin accounts for over 95% of Western Australian and over 60% of the Australian total hydrocarbon production (Australian Bureau of Agricultural and Resource Economics, 2010; Department of Mines and Petroleum, Western Australia, 2010b). In 2009, 64 new wells were drilled in the offshore Northern Carnarvon Basin, of which 22 were wildcat wells (Department of Mines and Petroleum, Western Australia, 2010a). There were 28 production areas and fields in 2009 (Australian Petroleum Production and Exploration Association, 2010). Reservoirs, Seals and Trap Styles Reservoir formations in the Northern Carnarvon Basin are dominated by fluvio-deltaic and marginal marine sandstones, such as those within the Triassic Mungaroo Formation, the Bajocian–Callovian Legendre Formation in the Dampier and Beagle sub-basins, and the Berriasian–Valanginian Barrow Group in the Barrow and Exmouth sub-basins and the Exmouth Plateau (Figure 9). The stratigraphic level of top-porosity across the basin generally becomes younger landward. Most hydrocarbon discoveries within the basin are hosted by reservoirs beneath the Lower Cretaceous Muderong Shale, which forms an effective regional seal and has contributed to a high exploration success rate (Baillie and Jacobson, 1997). Notable exceptions occur in the Barrow Sub-basin, where top seals are formed by the Aptian Windalia Radiolarite at the Barrow Island oil field and the Paleocene Dockerell Formation at the Maitland gas accumulation. In addition, intra-formational seals result in stacked hydrocarbon-bearing reservoirs. Gas accumulations on the Rankin Platform are top-sealed by a combination of the regional seal and intra-formational claystones. Significant intra-formational seals occur within the Berriasian–Valanginian Barrow Group, Forestier Claystone and equivalents, the Toarcian–Callovian Athol and Legendre formations, and the Triassic Mungaroo Formation. The main structural trap styles in the basin are horsts, tilted fault blocks, drapes and fault roll-over anticlines. Stratigraphic trap styles include basinfloor and turbidite fans, unconformity pinch-outs and onlaps. Structural compartmentalisation of the basin has resulted in complex trap evolution and charge histories. Figure 9 shows the major oil and gas accumulations discovered in the Northern Carnarvon Basin. Hydrocarbon Families and Source Rocks Two broad hydrocarbon families are recognised in the Northern Carnarvon Basin: one gas prone and derived from Triassic to Middle Jurassic fluvio2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 9 of 22 deltaic facies; and the other oil prone and sourced from Upper Jurassic marine sediments. The main gas source rocks in the Barrow, Dampier and Exmouth sub-basins are the Triassic fluvio-deltaic sediments of the Mungaroo Formation, Upper Triassic to Lower Jurassic marine sediments of the Brigadier Formation and the Middle to Upper Jurassic deltaic Legendre Formation. The giant gas fields of the Exmouth Plateau (Figure 9) were charged probably from deeply buried coal and carbonaceous claystone in the Mungaroo Formation, where peak gas generation is currently expected at depths of over 5000 m below sea floor (Bussell et al, 2001). Geochemical studies indicate that the gas accumulations of the Rankin Platform (Figure 9) accessed these Triassic sources as well as Lower–Middle Jurassic sources in the adjacent Barrow and Dampier subbasins (Boreham et al, 2001; Edwards and Zumberge, 2005; Edwards et al, 2007). The principal oil source in the Northern Carnarvon Basin is the Upper Jurassic Dingo Claystone. It was deposited under deep, restricted marine conditions in the Exmouth, Barrow and Dampier sub-basins. However, biomarker and geochemical studies indicate a significant supplementary contribution from terrestrial organic matter (Summons et al, 1998). The Oxfordian interval (W. spectabilis biozone) is particularly organic rich (van Aarssen et al, 1996). Hydrocarbon generation from the Dingo Claystone commenced in the Exmouth Sub-basin and southern parts of the Barrow Sub-basin in the Early Cretaceous with the loading of the Barrow Delta (Tindale et al, 1998; Smith et al, 2003). In contrast, the main phase of generation in the Dampier Sub-basin was in the Cenozoic, in response to the progradation of the carbonate shelf. These two broad hydrocarbon families are considered to be the source of almost all the commercially developed accumulations within the Northern Carnarvon Basin (Figure 9). However, geochemical studies have identified some vagrant oils which do not fall into these families (Summons et al, 1998). Lacustrine sources have been ascribed to the Nebo oil accumulation in the Beagle Sub-basin and at Rough Range in the onshore Exmouth Sub-basin (Longley et al, 2002; Edwards and Zumberge, 2005). Regional Petroleum Systems On the basis of a USGS analysis (Bishop, 1999), two petroleum systems are recognised in the Northern Carnarvon Basin: the ‘Locker/Mungaroo– Mungaroo/Barrow’ Petroleum System, and the ‘Dingo–Mungaroo/Barrow’ Petroleum System. The gas-prone ‘Locker/Mungaroo–Mungaroo/Barrow’ Petroleum System covers most of the basin to the margins to the Exmouth Plateau. It is primarily sourced from the Triassic Mungaroo Formation. However, basin modelling suggests that the underlying Locker Shale may also have contributed to the hydrocarbon charge. From a regional perspective, the ‘Locker/Mungaroo– Mungaroo/Barrow’ Petroleum System can be considered part of the Westralian 1 Petroleum Supersystem (Bradshaw et al, 1994; Edwards et al, 2007). This Supersystem includes giant gas accumulations sourced mainly 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 10 of 22 from fluvio-deltaic Triassic to Lower–Middle Jurassic source rocks in the Bonaparte, Browse and Northern Carnarvon basins. Similarities in the carbon isotopic profiles of gases and condensates across the Westralian Superbasin reflect the regional extent of fluvio-deltaic environments that developed from the Triassic to Middle Jurassic (Edwards and Zumberge, 2005; Edwards et al, 2007). The oil-prone ‘Dingo–Mungaroo/Barrow’ Petroleum System (Bishop, 1999) is restricted to the Exmouth, Barrow and Dampier sub-basins, and is principally sourced from the Upper Jurassic Dingo Claystone. It can be considered part of the Westralian 2 Petroleum Supersystem (Bradshaw et al, 1994; Edwards and Zumberge, 2005; Edwards et al, 2007). Geochemically similar oils are recognised in the Northern Carnarvon, Bonaparte and Papuan basins, all derived from Upper Jurassic marine source rocks deposited in incipient rifts that developed along the northern and northwestern continental margin during Gondwana breakup. 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 11 of 22 EXPLORATION HISTORY The first flow of oil to the surface in Australia was recorded in 1953 at Rough Range 1, in the onshore part of the Exmouth Sub-basin. The well recorded an oil flow of 500 bopd (79.5 kL/d) from the Lower Cretaceous Birdrong Sandstone, but further drilling on the same anticline failed to replicate the initial success (Bradshaw et al, 1999; Ellis and Jonasson, 2002). Exploration in the offshore Northern Carnarvon Basin during the 1960s and early 1970s established the basin as a major hydrocarbon province (Mitchelmore and Smith, 1994). The giant Barrow Island oil field was discovered in the Barrow Sub-basin in 1964, the Legendre 1 oil discovery in 1968 attracted exploration interest to the Dampier Sub-basin, and a series of multi-Tcf gas discoveries were made in the 1970s on the Rankin Platform (e.g. North Rankin, Angel, Goodwyn, Perseus). The Gorgon field, discovered in 1979, is one of the largest gas fields within the North Carnarvon Basin. On the deepwater Exmouth Plateau, a giant gas accumulation in a Lower Cretaceous Barrow Group basin floor fan was discovered in Scarborough 1 in 1980. In 1984, the North West Shelf Venture commenced domestic gas production from the North Rankin field and in 1989 the first LNG cargo was shipped to Japan. Since then, the project has contributed $70 billion to Australia’s gross domestic product (Woodside Petroleum Ltd, 2009b). From the early 1980s to the mid-1990s, a number of significant, mostly medium-sized oil (and gas) discoveries were made in the Barrow and Dampier sub-basins, as a result of the application of dense 2D seismic surveys (Longley et al, 2002). These include South Pepper, Chervil, Harriet and Saladin in the Barrow Sub-basin and Wanaea, Stag and Wandoo in the Dampier Sub-basin. The oil discovery at Nebo 1 in 1993 extended exploration interest into the under-explored Beagle Sub-basin. 3D seismic and AVO technology have contributed to an improvement in the success rate of recent exploration activities, despite the comparatively high level of exploration maturity (Longley et al, 2002; Korn et al, 2003; Williamson and Kroh, 2007). In the Dampier Sub-basin, the productive oil trend has now been extended northward to the Mutineer and Exeter fields. In the Exmouth Sub-basin, the 1999 Enfield discovery has been followed by a string of oil finds including Coniston, Laverda, Stybarrow, Ravensworth and Stickle, and oil production is under way from the Enfield, Stybarrow and Eskdale fields. Growing demand for LNG has stimulated exploration along the Rankin Platform and on the Exmouth Plateau in recent years, mostly targeting Triassic fault block and intra-Triassic plays. However, the supergiant Io–Jansz gas field, discovered in 2000 on the Exmouth Plateau is hosted by an Oxfordian shallow-marine sandstone (Jenkins et al, 2003). Other recent large gas discoveries over the Rankin Platform and inboard areas of the Exmouth Plateau have been made at Wheatstone, Pluto, Xena, Achilles, Satyr, Sappho and Clio. The significant gas discovery at Acme 1, with a net gas pay of 273 m, has the potential to feed into the Wheatstone LNG project (Chevron 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 12 of 22 Australia Pty Ltd, 2010a). Apache Corporation has made several significant discoveries on the Julimar trend between the Gorgon and Pluto fields, including the Julimar and Brunello gas fields and the Balnaves oil accumulation (Apache Corporation, 2010a). Hess Corporation has recorded over 10 discoveries in a work program comprising 16 wells within WA-390-P, southwest of the Io–Jansz field (Jonasson and Mack, 2010). The multi-Tcf gas fields discovered at Thebe 1, which intersected a gross gas column of 73 m (BHP Billiton Ltd, 2007), Martell 1, with a gross gas column of 110 m (Woodside Petroleum Ltd, 2009a, and at Noblige 1, with gas indications over a 300 m gross interval (Woodside Petroleum Ltd, 2010b), have extended the northerly limit of known gas accumulations on the Exmouth Plateau. The 185 m gas column discovered at Alaric 1 (Woodside Petroleum Ltd, 2010a) has proven that the prospective zone extends to the deepwater western margins of the Exmouth Plateau. Other major recent gas discoveries in outer areas of the Exmouth Plateau include Chandon, Yellowglen, Brederode, Kentish Knock, Larsen Deep and Remy. Accompanying the recent discoveries have been a series of new, large-scale development projects and associated investment in infrastructure. The Pluto LNG project, operated by Woodside Petroleum Ltd, consists of a processing plant on the Burrup Peninsula for gas from the Pluto and Xena fields with an expansion plan for three or more LNG trains and a pipeline gas facility (Woodside Petroleum Ltd, 2010c). The plant is expected to commence production in 2011. The Gorgon LNG project, the largest resource development project in Australia, incorporates a 15 Mtpa LNG plant on Barrow Island and a large-scale carbon dioxide reinjection project. This project is operated by Chevron, ExxonMobil and Shell and the first LNG production is planned for 2014 (Chevron Australia Pty Ltd, 2010b). The Wheatstone LNG project, operated by Chevron, will process gas from the Wheatstone and Iago fields via a two-train plant at Ashburton North (Chevron Australia Pty Ltd, 2010c). Apache and Kuwait Foreign Petroleum Exploration Co. (KUFPEC) plan to supply additional gas from the Julimar–Brunello project to the Wheatstone LNG plant (Apache Corporation, 2010a), which may eventually produce up to 25 Mtpa of LNG (Chevron Australia Pty Ltd, 2010c). Extension of the North West Shelf Venture is in progress, including the conversion of the Cossack–Wanaea–Lambert–Hermes FPSO and the North Rankin B Gas Compression project (BHP BiIliton Ltd, 2010b). Planning for the development of the Scarborough and Thebe fields is underway. Some of the fields in the inboard areas of the Northern Carnarvon Basin are also being developed. The Pyrenees project commenced production from the Crosby, Ravensworth and Stickle oil fields in the Exmouth Sub-basin in 2010. The project, operated by BHP Billiton, involves 13 subsea wells tied back to an FPSO (BHP Billiton Ltd, 2010c). Gas produced will be reinjected into the neaby Macedon gas field. The latter field will be developed through the BHP Billiton-operated Macedon project, which will supply domestic gas via a processing plant to be constructed at Ashburton North, to the Dampier to Bunbury Natural Gas Pipeline (BHP Billiton Ltd, 2010a). Production is expected to commence in 2013 (BHP Billiton Ltd, 2010a). The Van Gogh oil 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 13 of 22 field, also in the Exmouth Sub-basin, commenced production in early 2010 using an FPSO operated by Apache Energy (Apache Corporation, 2010b). Apache Energy’s Devil’s Creek Development project will commence supply of domestic gas from the Reindeer field in the Dampier Sub-basin to the Dampier–Bunbury Natural Gas Pipeline via a new offshore pipeline and an onshore processing plant by 2011 (Apache Corporation, 2009). 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 14 of 22 FIGURES Figure 1: Structural elements of the Northern Carnarvon Basin and adjacent basins showing the 2011 Release Areas, oil and gas accumulations and selected wells. Figure 2: Petroleum production facilities, hydrocarbon accumulations and pipeline infrastructure in the Northern Carnarvon Basin. Figure 3: Map of the Northern Carnarvon Basin with the location of regional geological cross-sections shown in Figure 4, Figure 5, Figure 6 and Figure 7. Figure 4: Geological cross-section along AGSO seismic line 110/12 from the western Exmouth Plateau to the southwestern Barrow Subbasin (see Figure 3 for location) Figure 5: Geological cross-section along reprocessed AGSO seismic line 101r/09 from the central Exmouth Plateau across the Dampier Sub-basin (see Figure 3 for location) Figure 6: Geological cross-section along AGSO seismic line 110/03 across the southwestern Beagle Sub-basin and the Lambert Shelf (see Figure 3 for location). Figure 7: Geological cross-section along AGSO seismic line 120/14 across the northeastern Exmouth Plateau, the northern Beagle Sub-basin and the Roebuck Basin (see Figure 3 for location). Figure 8: Generalised stratigraphy of the Northern Carnarvon Basin, based on the Northern Carnarvon Basin Biozonation and Stratigraphy Chart (Nicoll et al, 2010). Geologic Time Scale after Gradstein et al (2004) and Ogg et al (2008). Figure 9: Major oil and gas fields and discoveries in the Northern Carnarvon Basin indicating age of the main reservoir. 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 15 of 22 REFERENCES APACHE CORPORATION, 2009—[Web page] Groundbreaking signals commencement of new WA domestic gas hub. http://investor.apachecorp.com/releasedetail.cfm?ReleaseID=409139 (last accessed 29 October 2010). APACHE CORPORATION, 2010a—[Web page] Apaches plans Balnaves field development offshore Western Australia after appraisal well tests 9076 barrels of oil, 13 MMcf of gas per day. http://investor.apachecorp.com/releasedetail.cfm?ReleaseID=518396 (last accessed 27 October 2010). APACHE CORPORATION, 2010b—[Web page] Operations, Australia. http://www.apachecorp.com/Operations/Australia/index.aspx (last accessed 21 January 2010). AUSTRALIAN BUREAU OF AGRICULTURAL AND RESOURCE ECONOMICS, 2010—Energy in Australia 2010. Canberra: Department of Resources Energy and Tourism, 87p. AUSTRALIAN PETROLEUM PRODUCTION AND EXPLORATION ASSOCIATION, 2010—2009 production statistics. http://www.appea.com.au/images/stories/Statistics/Annual_Production_Statisti cs.xls (last accessed 26 October 2010). BAILLIE, P.W. AND JACOBSON, E.P., 1997—Prospectivity and exploration history of the Barrow Sub-basin, Western Australia. The APPEA Journal, 37 (1), 117–135. BARBER, P., 1988—The Exmouth Plateau deepwater frontier: a case study. In: Purcell, P.G. and Purcell, R.R. (eds), The North West Shelf, Australia. Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, 173–187. BARBER, P., 1994—Late Jurassic–Early Cretaceous depositional systems of the Dampier Sub-basin – quo vadis? The APEA Journal 34 (1), 566–585. BHP BILLITON LTD., 2007—[Web page] BHP Billiton announces gas discovery at Thebe-1 offshore Australia. http://www.bhpbilliton.com/bb/investorsMedia/news/2007/bhpBillitonAnnounce sGasDiscoveryAtThebe1OffshoreAustralia.jsp (last accessed 27 October 2010). BHP BILLITON LTD., 2010a—[Web page] BHP Billiton aproves Macedon Gas development in Western Australia, 24 September 2010 http://www.bhpbilliton.com/bb/investorsMedia/news/2010/bhpBillitonApproves MacedonGasDevelopmentInWesternAustralia.jsp (last accessed 27 October 2010). 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 16 of 22 BHP BILLITON LTD., 2010b—[Web page] BHP Billiton Petroleum Annual Review 2010. http://www.bhpbilliton.com/bbContentRepository/docs/bhpBillitonPetroleumAn nualReview2010.pdf (last accessed 27 October 2010). BHP BILLITON LTD., 2010c—[Web page] First oil production from Pyrenees development offshore Western Australia. http://www.bhpbilliton.com/bb/investorsMedia/news/2010/firstOilProductionFro mPyreneesDevelopmentOffshoreWesternAustralia.jsp (last accessed 27 October 2010). BISHOP, M.G., 1999—Total Petroleum Systems of the Northwest Shelf, Australia: the Dingo-Mungaroo/Barrow and Locker-Mungaroo/Barrow. U.S. Department of the Interior, U.S. Geological Survey, Open File Report 99-50-E, http://greenwood.cr.usgs.gov/energy/WorldEnergy/OF99-50E/ (last accessed 21 January 2010). BLEVIN, J.E., STEPHENSON, A.E. AND WEST, B.G., 1994—Mesozoic structural development of the Beagle Sub-basin—implications for the petroleum potential of the Northern Carnarvon Basin. In: Purcell, P.G. and Purcell, R.R. (eds), The Sedimentary Basins of Western Australia: Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, 1994, 369–396. BOOTE, D.R.D. AND KIRK, R.B., 1989—Depositional wedge cycles on evolving plate margin, western and northwestern Australia. AAPG Bulletin, 73 (2), 216–243. BOREHAM, C.J., HOPE, J.M. AND HARTUNG-KAGI, B., 2001— Understanding source, distribution and preservation of Australian natural gas: a geochemical perspective. The APPEA Journal, 41(1), 523–547. BRADSHAW, M.T., YEATES, A.N., BEYNON, R.M., BRAKEL, A.T., LANGFORD, R.P., TOTTERDELL, J.M. AND YEUNG, M., 1988— Palaeogeographic evolution of the North West Shelf region. In: Purcell, P.G. and Purcell, R.R. (eds), The North West Shelf, Australia. Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, 1988, 29–54. BRADSHAW, M.T., BRADSHAW, J., MURRAY, A., NEEDHAM, D.J., SPENCER, L., SUMMONS, R., WILMOT, J. AND WINN, S., 1994— Petroleum systems in West Australian basins. In: Purcell, P.G. and Purcell, R.R. (eds), The Sedimentary Basins of Western Australia. Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, 1994, 93–118. BRADSHAW, M.T., FOSTER, C.B., FELLOWS, M.E. AND ROWLAND, D.C., 1999—The Australian search for petroleum-patterns of discovery. The APPEA Journal, 39 (1), 1–18. BUSSELL, M.R., JABLONSKI, D., ENMAN, T., WILSON, M.J. AND BINT, A.N., 2001—Deepwater exploration: northern Western Australia compared with Gulf of Mexico and Mauritania. The APPEA Journal, 41(1), 289–319. 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 17 of 22 CATHRO, D.L. AND KARNER, G.D., 2006—Cretaceous–Tertiary inversion history of the Dampier Sub-basin, northwest Australia: insights from quantitative basin modelling. Marine and Petroleum Geology, 23, 503–526. CHEVRON AUSTRALIA PTY LTD., 2010a—[Web page] Chevron Announces Significant Natural Gas Find in Australia. http://www.chevronaustralia.com/media/mediastatements.aspx?NewsItem=7d 260361-7c34-4f0d-84db-ca1019c3181e (last accessed 27 October 2010). CHEVRON AUSTRALIA PTY LTD., 2010b—[Web page] Gorgon—its time is now. http://www.chevronaustralia.com/ourbusinesses/gorgon.aspx#z (last accessed 27 October 2010). CHEVRON AUSTRALIA PTY LTD., 2010c—[Web page] Wheatstone. http://www.chevronaustralia.com/ourbusinesses/wheatstone.aspx#z (last accessed 27 October 2010). DEPARTMENT OF MINES AND PETROLEUM, WESTERN AUSTRALIA, 2010a——[Web page] Petroleum wells in Western Australia 2009 Calendar Year statistical summary http://www.dmp.wa.gov.au/documents/Wells09.pdf (last accessed 26 October 2010). DEPARTMENT OF MINES AND PETROLEUM, WESTERN AUSTRALIA, 2010b——[Web page] Production Statistics http://www.dmp.wa.gov.au/1938.aspx (last accessed 26 October 2010). DRISCOLL, N.W. AND KARNER, G.D., 1998—Lower crustal extension across the Northern Carnarvon Basin, Australia: evidence for an eastward dipping detachment. Journal of Geophysical Research, 103(B3), 4975–4991. EDWARDS, D. AND ZUMBERGE, J., 2005—The Oils of Western Australia II: Regional Petroleum Geochemistry and Correlation of Crude Oils and Condensates from Western Australia and Papua and New Guinea. Geoscience Australia and GeoMark Research Ltd., unpublished. EDWARDS, D.S., ZUMBERGE, J.E., BOREHAM, C.J., KENNARD, J.M., BARRETT, A. AND BRADSHAW, M.T., 2007—Petroleum Systems and Supersystems of the Australian North West Shelf: A Geochemical Approach. Abstract, Geological Society of London: Emerging Plays in Australasia Symposium, July 2007. ELLIS, G.K. AND JONASSON, K.E., 2002—Rough Range Oil Field, Carnarvon Basin. In: Keep, M. and Moss, S.J. (eds), The Sedimentary Basins of Western Australia 3: Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, 707–718. ELLIS, G.K., PITCHFORD, A. AND BRUCE, R.H., 1999—Barrow Island oil field. The APPEA Journal, 39 (1), 158–175. GRADSTEIN, F.M., OGG, J.G., AND SMITH, A.G. (EDITORS), 2004— Geologic Time Scale 2004. Cambridge: Cambridge University Press, 550 p. 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 18 of 22 HEARTY, D.J., ELLIS, G.K. AND WEBSTER, K.A., 2002—Geological history of the western Barrow Sub-basin: implications for hydrocarbon entrapment at Woollybutt and surrounding oil and gas fields. In: Keep, M. and Moss, S.J. (eds), The Sedimentary Basins of Western Australia 3: Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, 577–598. HOCKING, R.M., 1990—Carnarvon Basin. In: Geology and Mineral Resources of Western Australia. Western Australia Geological Survey, Memoir 3, 457–495. JABLONSKI, D., 1997—Recent advances in the sequence stratigraphy of the Triassic to Lower Cretaceous succession in the Northern Carnarvon Basin, Australia. The APPEA Journal, 37 (1), 429–454. JABLONSKI, D. AND SAITTA, A.J., 2004—Permian to Lower Cretaceous plate tectonics and its impact on the tectono-stratigraphic development of the western Australian margin. The APPEA Journal, 44 (1) 287–327. JENKINS, C.C., MAUGHAN, D.M., ACTON, J.H., DUCKETT, A., KORN, B.E. AND TEAKLE, R.P., 2003—The Jansz gas field, Carnarvon Basin, Australia. The APPEA Journal, 43 (1), 303–324. JONASSON, K. AND MACK, C. 2010. Petroleum exploration, production and development activity in Western Australia—Highlights from January to June 2010. Petroleum in Western Australia, September 2010, 6–13. KOPSEN, E. AND McGANN, G., 1985—A review of the hydrocarbon habitat of the eastern and central Barrow-Dampier Sub-basin, Western Australia. The APEA Journal, 25 (1), 154–176. KORN, B.E., TEAKLE, R.P., MAUGHAN, D.M. AND SIFFLEET, P.B., 2003— The Geryon, Orthrus, Maenad and Urania gas fields, Carnarvon Basin, Western Australia. The APPEA Journal, 43 (1), 285–301. LONGLEY, I.M., BUESSENSCHUETT, C., CLYDSDALE, L., CUBITT, C.J., DAVIS, R.C., JOHNSON, M.K., MARSHALL, N.M., MURRAY, A.P., SOMERVILLE, R., SPRY, T.B. AND THOMPSON, N.B., 2002—The North West Shelf of Australia – a Woodside perspective. In: Keep, M. and Moss, S.J. (eds), The Sedimentary Basins of Western Australia 3: Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, 27–88. MALCOLM, R.J., POTT, M.C. AND DELFOS, E., 1991—A new tectonostratigraphic synthesis of the North West Cape area. The APEA Journal, 31(1), 154–176. MITCHELMORE, L. AND SMITH, N., 1994—West Muiron discovery, WA-155-P - new life for an old prospect. In: Purcell, P.G. and R.R. (eds), The Sedimentary Basins of Western Australia. Proceedings of Petroleum Exploration Society of Australia Symposium, Perth, 1994, 583–596. 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 19 of 22 MOSS, S., BARR, D., KNEALE, R., CLEWS, P. AND CRUSE, T., 2003—Mid to Late Jurassic shallow marine sequences of the eastern Barrow Sub-basin: the role of low-stand deposition in new exploration concepts. The APPEA Journal, 43 (1), 231–255. NEWMAN, S., 1994—Clues to the structural history of the Rankin Trend, from 3-D seismic data. In: Purcell, P.G. and Purcell, R.R. (eds), The Sedimentary Basins of Western Australia: Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, 497–507. NORVICK, M.S., 2002—Palaeogeographic Maps of the Northern Margins of the Australian Plate: Final Report. Unpublished report for Geoscience Australia. OGG, J.G., OGG, G. AND GRADSTEIN, F.M., 2008—Concise Geologic Time Scale. Cambridge: Cambridge University Press, 177p. POLOMKA, S.M. AND LEMON, N.M., 1996—Tectono-stratigraphic evolution of the Barrow Sub-basin, North West Shelf: a discussion on nomenclature revision. PESA Journal 24, 105–115. ROMINE, K.K., DURRANT, J.M., CATHRO, D.L. AND BERNARDEL, G., 1997—Petroleum play element prediction for the Cretaceous–Tertiary basin phase, Northern Carnarvon Basin. The APPEA Journal 37, 315–339. ROSS, M.I. AND VAIL, P.R., 1994—Sequence stratigraphy of the lower Neocomian Barrow Delta, Exmouth Plateau, northwestern Australia. In: Purcell, P.G. and Purcell, R.R. (eds), The Sedimentary Basins of Western Australia: Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, 1994, 435–447. SEGGIE, R.J., LAND, S.C., MARSHALL, N.M., CUBITT, C.J., ALSOP, D., KIRK, R. AND TWARTZ, S., 2007—Integrated multi-disciplinary analysis of the Rankin Trend gas reservoirs, North West Shelf, Australia. The APPEA Journal, 47 (1), 53–67. SIBLEY, D., HERKENHOFF, F., CRIDDLE, D. AND McLERIE, M., 1999— Reducing resource uncertainty using seismic amplitude analysis on the southern Rankin Trend, northwest Australia. The APPEA Journal. 39 (1), 128–147. SMITH, S.A., TINGATE, P.R., GRIFFITHS, C.M. AND HULL, J.N.F., 1999— The structural development and petroleum potential of the Roebuck Basin. The APPEA Journal, 39 (1), 364–385. SMITH, N., DEMPSEY, C., JACKSON, M. AND PRESTON, J., 2003— Overcoming historical bias: an integrated geological and engineering assessment of the Coniston prospect, Exmouth Sub-basin. The APPEA Journal, 43 (1), 363–383. 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 20 of 22 STAGG, H.M.J., ALCOCK, M.B., BERNARDEL, G., MOORE, A.M.G., SYMONDS, P.A. AND EXON, N.F., 2004—Geological framework of the Outer Exmouth Plateau and adjacent ocean basins. Geoscience Australia Record 2004/13. STAGG, H.M.J. AND COLWELL, J.B., 1994—The structural foundations of the Northern Carnarvon Basin. In: Purcell, P.G. and Purcell, R.R. (eds), The Sedimentary Basins of Western Australia: Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, 1994, 349–364. SUMMONS, R.E., BRADSHAW, M., CROWLEY,J., EDWARDS D. S., GEORGE, S.C. AND ZUMBERGE, J.E., 1998—Vagrant oils: geochemical signposts to unrecognised petroleum systems. In: Purcell, P.G. and Purcell, R.R. (eds), The Sedimentary Basins of Western Australia: Proceedings of Petroleum Exploration Society of Australia Symposium, Perth, 1998, 169– 184. TINDALE, K., NEWELL, N., KEALL, J. AND SMITH, N., 1998—Structural evolution and charge history of the Exmouth Sub-basin, Northern Carnarvon Basin, Western Australia. In: Purcell, P.G. and Purcell, R.R. (eds), The Sedimentary Basins of Western Australia 2: Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, 1998, 447–472. van AARSSEN, R., ALEXANDER, R. AND KAGI, R.I., 1996—The origin of Barrow Sub-basin crude oils: a geochemical correlation using land-plant biomarkers. The APPEA Journal, 36 (1), 131–144. von RAD, U., EXON, N.F., BOYD, R. AND HAQ, B.U., 1992a—Mesozoic paleoenvironments of the rifted margin off NW Australia (ODP Legs 122/123). American Geophysical Union, Geophysical Monograph, 70, 157–184. von RAD, U., HAQ, B.U. AND OTHERS, 1992b—Proceedings of Ocean Drilling Program, Initial Reports, 122. Ocean Drilling Program, College Station, Texas, 934 pp. WESTPHAL, H. AND AIGNER, T., 1997—Seismic stratigraphy and subsidence analysis in the Barrow-Dampier Sub-basin, northwest Australia. AAPG Bulletin, 81 (10), 1721–1749. WILLIAMSON, P.E. AND KROH, F., 2007—The role of amplitude versus offset technology in promotion of offshore petroleum exploration in Australia. The APPEA Journal, 47 (1), 161–174. WOODSIDE OFFSHORE PETROLEUM PTY LTD, 1988—A review of the petroleum geology and hydrocarbon potential of the Barrow/Dampier Subbasin and environs. In: Purcell, P.G. and Purcell, R.R. (eds), The North West Shelf Australia: Proceedings of the Petroleum Exploration Society of Australia Symposium, Perth, 1988, 115–128. WOODSIDE PETROLEUM LTD., 2009a—[Web page] Martell gas discovery update. http://www.woodside.com.au/NR/rdonlyres/ECC18A32-9C7A-49712011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 21 of 22 90C4-96FABA6306FE/0/MartellGasDiscoveryUpdate.pdf (last accessed 21 January 2010). WOODSIDE PETROLEUM LTD., 2009b—[Web page] North West Shelf Venture drives economic transformation in Australia. http://www.woodside.com.au/NR/rdonlyres/AFD92952-8295-43C3-BAB2E3290296F031/0/NWSV_25_year_ACIL_Tasman_report_launch_media_rele ase_Canberra_20_October_2009.pdf (last accessed 21 January 2010) WOODSIDE PETROLEUM LTD., 2010a—[Web page] Gas discovery at Alaric. http://www.woodside.com.au/NR/rdonlyres/79013843-4776-41C0B31B-920630672289/0/ASX036GasDiscoveryatAlaric.pdf WOODSIDE PETROLEUM LTD., 2010b—[Web page] Gas encountered in Noblige well. http://www.woodside.com.au/NR/rdonlyres/7C4892BC-43384224-91DA-47FD4A4B79FD/0/GasEncounteredinNobligeWell.pdf WOODSIDE PETROLEUM LTD., 2010c—[Web page] Pluto LNG Project. http://www.woodside.com.au/Our+Business/Projects/Pluto/About+Pluto.htm (last accessed 27 October 2010). Front page image courtesy of Petroleum Geo-Services. 2011 Release of Australian Offshore Petroleum Exploration Areas Regional Geology of the Carnarvon Basin Page 22 of 22