W10-20 - Department of Resources, Energy and Tourism

Image: Woodside Energy Ltd. 

AustrAliA 2010 

exmouth plAteAu 

NortherN CArNArvoN BAsiN 

releAse AreAs W10-20, W10-21 ANd W10-22 

Offshore Petroleum Exploration Acreage Release

CoNteNts 

GEOlOGicAl infORmAtiOn 1 

lOcAtiOn 1 

RElEAsE AREA GEOlOGy 2 

ExPlORAtiOn HistORy 3 

PEtROlEum systEms And HydROcARbOn POtEntiAl 9 

fiGuREs 11 

REfEREncEs 19 

Figures 

Figure 1: location map of Release Areas W10-20, W10-21 and W10-22, Exmouth 

Plateau, carnarvon basin. 11 

Figure 2: Graticular block map and graticular block listings for Release Areas 

W10-20, W10-21 and W10-22. 12 

Figure 3: structural elements of the Exmouth Plateau showing 2010 Release 

Areas and location of seismic section shown in Figure 5. 14 

Figure 4: Generalised stratigraphy of the Exmouth Plateau, tied to the geological 

timescale after Gradstein et al (2004) and Ogg et al (2008). 15 

Figure 5: Geoscience Australia seismic line 110/15 across the central and outer 

Exmouth Plateau. 16 

Figure 6: major oil and gas accumulations on the Exmouth Plateau indicating age 

of main reservoir. 17 

Figure 7: Play types on the Exmouth Plateau (modified from Woodside, 

2009b). lower cretaceous barrow Group basin floor fan and turbidite plays (eg 

scarborough, nimblefoot and briseis shallow) not shown. 18

geologiCAl iNFormAtioN 

releAse AreAs W10-20, W10-21 ANd W10-22, exmouth 

plAteAu, NortherN CArNArvoN BAsiN 

WesterN AustrAliA 

Bids Close – 11 November 2010 

• Australia’s premier deepwater gas province. 

• Adjacent to multi-tcf gas fields. 

• fault block and structural/stratigraphic traps. 

• construction and planned expansion of regional lnG facilities. 

• Water depths 900-1200 m. 

• special notices apply, refer to Guidance notes. 

loCAtioN 

Release Areas W10-20, W10-21 and W10-22 are located in deep water about 300 km off the coast 

of Western Australia on the central portion of the Exmouth Plateau, within the northern carnarvon 

basin (Figure 1). the three Release Areas represent the recently relinquished portions of Permit 

WA-346-P which was originally granted on 16/07/2003 and subsequently renewed on 15/10/2009. 

the Release Areas are adjacent to the multi-tcf thebe gas field, and immediately north of the giant 

~8 tcf (226 bcm) scarborough gas field. no wells have been drilled in the Release Areas. Water 

depths range from about 900 to1200 m. 

Gas production facilities are currently being developed for the nearby chevron operated Gorgon 

and Jansz-io fields and Woodside operated Pluto field. Exxonmobil and bHP billiton are currently 

examining development options for the scarborough and thebe fields. 

the graticular block map and listings for the Release Areas are shown in Figure 2. 

Geology of Release Areas W10-20, W10-21 and W10-22 | www.petroleum-acreage.gov.au 1

eleAse AreA geology 

local tectonic setting 

the Exmouth Plateau is a deep water marginal Plateau that represents the western structural 

element of the northern carnarvon basin (Figure 3). most of the plateau is underlain by 10–15 km 

of generally flat-lying and block faulted, tilted lower cretaceous, Jurassic, triassic and older 

sedimentary section (Figure 4 and Figure 5) that was deposited during the periods of extension 

that preceded breakup of Australia and Argo land in the middle Jurassic, and then Greater india in 

the Early cretaceous (stagg et al, 2004). the dominant fault trend on the Exmouth Plateau is northsouth, 

swinging to northeast-southwest near the northern and western outer margins of the plateau, 

and along the inner margin adjacent to the Rankin Platform and Exmouth–barrow–dampier subbasins 

(Figure 3). 

structural evolution and depositional history of the sub-basin 

the lower triassic of the carnarvon basin is marked by a regional marine transgression that 

represents the sag phase of a previous Paleozoic rift cycle. the marine locker shale (below td of 

wells on the Exmouth Plateau) unconformably overlies the Permian section and grades upwards 

into the middle–upper triassic mungaroo formation (Figure 4). the mungaroo formation was 

deposited in a broad, low relief, rapidly subsiding fluvio-deltaic coastal plain that extended across 

the Exmouth Plateau. during marine transgression in the latest triassic (Rhaetian), carbonate patch 

reefs developed on the Wombat Plateau (von Rad et al, 1992a; Williamson et al, 1989) and probably 

extended across the northern – and western-central parts of the Exmouth Plateau. coeval marls, 

siltstones and thin sandstones (brigadier formation) were also deposited at this time on the Exmouth 

Plateau. 

As rifting proceeded between Australia and Greater india, several phases of faulting occurred in 

the Jurassic. in the Pliensbachian, rifting inboard of the Exmouth Plateau formed the Exmouth, 

barrow and dampier sub-basins. several kilometres of marine Jurassic sediments were deposited in 

these troughs that are the equivalent of condensed sections on the central Exmouth Plateau (dingo 

claystone equivalents). the major movement on extensional faults on the Exmouth Plateau occurred 

in the callovian, and continuous oceanic crust was created in the Argo Abyssal Plain to the north 

in the late Oxfordian, and in the Gascoyne and cuvier Abyssal Plains to the west and south in the 

Valanginian (norvick, 2002). Rift and breakup volcanics are widespread along the outer margins of 

the Exmouth Plateau, and probably include late triassic, Oxfordian/callovian and Early cretaceous 

volcanism (stagg et al, 2004). 

On the eastern portion of the Exmouth sub-basin, late Jurassic deposition of sandy shelfal facies 

occurred within restricted shallow depocentres (including the Oxfordian Jansz sandstone reservoir 

at the giant Jansz-io gas accumulation). during the Early cretaceous the barrow Group delta 

prograded northward across the southern portion of the plateau to form a major sediment lobe with 

the shelf edge arching through or near the investigator 1 and Zeepard 1 well locations (boote and 

Kirk, 1989); basin floor fans of this succession form the reservoir at the scarborough gas field. 

As the newly formed oceanic crust of the flanking Argo, Gascoyne and cuvier abyssal plains rapidly 

subsided, the Exmouth Plateau also foundered and was progressively transgressed throughout the 

cretaceous by shallow marine mudstone (muderong shale) and siltstone (Gearle siltstone), midouter 

shelf marl and chalk (toolonga calcilutite), and finally cenozoic bathyal chalk and ooze. 


explorAtioN history 

two major exploration campaigns have focused on the deepwater Exmouth Plateau, the first in 1979 

to 1980 for oil targets, and the second currently underway searching for gas. the initial exploration 

programs undertaken by Esso and Phillips (barber, 1988) began when no proven technology 

existed to develop a deepwater oil field. Eleven deepwater (740–1375 m) wells were drilled in the 

initial exploration phase (Walker, 2007), with the anticipation of oil charge from the Jurassic dingo 

claystone. two wells were gas discoveries: Jupiter 1, a triassic horst trap; and scarborough 1, a giant 

gas accumulation in an inverted lower cretaceous barrow Group basin floor fan. At the time of the 

scarborough 1 discovery (1979), the available technology and the undeveloped lnG market made 

the remote, deepwater gas accumulation uneconomic to develop. All other wells drilled during this 

period had significant gas shows, but there were no oil discoveries. 

After the 1979-1980 drilling campaign no further exploration on the deepwater Exmouth Plateau 

was undertaken for over a decade. the second phase of activity commenced in the mid 1990s with 

a focus on the established triassic fault block play along the eastern margin of the Exmouth Plateau, 

outboard of the Rankin trend. Activity returned to the central Exmouth Plateau in 1996 with the 

appraisal drilling of the scarborough 2 well. Extensive acreage was released on the surrounding 

northern and western portions of the Exmouth Plateau in 2000, but failed to attract successful bids. 

the super-giant Jansz-io gas field, the largest discovery yet made on the Exmouth Plateau, was 

made by Jansz 1 (2000) and io 1 (2001) and represented a new Oxfordian play type on the Exmouth 

Plateau (Jenkins et al, 2003). following this discovery, gas became the primary exploration target 

and extensive new acreage was awarded on the central, northern and western portions of the 

Exmouth Plateau following successive acreage releases in the period 2002-2006. several 3d seismic 

surveys were carried out as part of the work program bids for these newly awarded permits. 

in 2007, bHP billiton drilled thebe 1 in Permit WA-346-P (immediately north of the adjoining 

scarborough retention lease) and discovered 2 to 3 tcf (57-85 bcm) of gas in a triassic fault block 

(bHP billiton, 2007; Anonymous, 2007). thebe 2 (2008) was drilled16 km to the north of the initial 

discovery and confirmed expectations of the size and quality of the thebe resource (bHP billiton, 

2008a). 

market conditions have changed markedly since the first phase of exploration on the Exmouth 

Plateau in the 1970s, with major gas trade established with Japan, contracts secured to supply 

lnG to china, production facilities under construction for Pluto, and development proposals being 

assessed at Wheatstone, scarborough and thebe. An indication of the viability of the deepwater 

frontier plays on the Exmouth Plateau was the competitive bidding for the 2006 Release Areas and 

the entry of a number of new explorers including Hess corporation and OmV. in 2007, Hess was 

awarded the deepwater petroleum exploration permit WA-390-P, located southwest of the supergiant 

Jansz-io field, with an aggressive bid including a 16 exploration well drilling commitment. 

the first three wells of their initial 2007 four well program were all gas discoveries (Glencoe 1, 

briseis 1 and nimblefoot 1) but the fourth (Warrior 1) was dry. in all three wells, accumulations 

occur within the post-callovian interval, with briseis 1 also encountering additional pay in the 

triassic mungaroo formation (smallwood et al, 2010). the Oxfordian (W. spectabilis) sandstones 

encountered in Glencoe 1 are analogous to those encountered at Jansz-io to the northeast. in 

contrast, nimblefoot 1 and briseis 1 both encountered gas pay within deep-water delta-front 

turbidite sandstones of berriasian age sourced from the barrow delta to the south, analogous to the 

scarborough gas field. 

Other recent giant gas finds have been made at Wheatstone 1 (2004) and Pluto 1 (2005) to the east, 

chandon 1 (2006) to the northwest, clio 1 (2006) to the southeast, and martell 1 (2009) to the north 

of the Jansz-io field (Figure 1). At the time of writing, Hess has completed six of its current 12 well 

drilling campaign (2009-2010) in Permit WA-390-P (toporoa 1, dunlop 1, lightfinger 1, bravo 1, 

Rimfire 1 and mentorc 1), but so far drilling results have not been disclosed. in the adjacent Permit 

WA-374-P to the east, chevron has reported a major gas discovery at Achilles 1 in five triassic 

mungaroo sandstones (chevron Australia, 2009a). 


most of the Exmouth Plateau is now under permit, with indicative work program commitments since 

2004 totalling approximately $1 billion, including nine guaranteed deepwater wells to be drilled in 

WA-404-P held jointly by Hess corporation and Woodside, and two exploration wells in the recently 

renewed WA-346-P permit adjacent to Release Areas W10-20 to W10-22. 3d seismic and AVO 

technology are key exploration tools that contribute to high success rates on the Exmouth Plateau 

(longley et al, 2002; Korn et al, 2003; Williamson and Kroh, 2007). 

Well Control 

no wells have been drilled within the Release Areas, but several are in close proximity (Jupiter 1, 

scarborough 1, thebe 1 and 2, Kentish Knock 1) and others provide important stratigraphic control 

or nearby gas discoveries (Figure 1). 

InvestIgator 1 (1979) 

investigator 1 was drilled by Esso Australia ltd to test delta front sandstones of the lower 

cretaceous barrow Group in a large closure formed by a combination of northward depositional dip 

on the delta front, regional south to southeast tilting of the Exmouth Plateau and gentle cenozoic 

arching about a northeast-trending axis (EssO Australia ltd, 1980a). the well was drilled in a water 

depth of 841 m and reached a td of 3745 mKb. it penetrated and sampled an Albian-barremian 

succession of claystone, marl and siltstone to 1492 mKb, overlying a 1748 m thick section of basinal 

to prodelta and delta front claystone, siltstone and sandstone of the target barrow Group. the 

barrow Group was underlain by a 15 m section of upper Jurassic claystone, middle-lower Jurassic 

marl (44 m), upper triassic (Rhaetian) marl (65 m) and upper triassic (norian) interbedded sandstone, 

siltstone claystone and minor coal of the mungaroo formation (382 m thick to td). sandstones of 

good reservoir quality occur within the barrow Group (13–30% porosity), but those within the upper 

triassic mungaroo formation were generally poor (5–16% porosity). 

no significant hydrocarbon shows were recorded in the target barrow Group reservoir, but elevated 

mud gas levels and small amounts of wet gas and questionable oil films in wireline tests were 

recorded in low permeability sandstones of the mungaroo formation. log analysis indicates 48–86% 

water saturation in these sandstones. the lack of hydrocarbons in the barrow Group sands was 

attributed to the absence of effective migration pathways for any hydrocarbons generated within the 

deeper mungaroo section. 

JupIter 1 (1979) 

Jupiter 1 was drilled by Phillips Australian Oil company in water depths of 960 m to test a 

tilted triassic horst (Figure 5). the well reached a total depth of 4946 mRt in a thick section of 

interbedded triassic siltstone, claystones, sandstone and minor coal and dolomite (A. reducta to 

S. quadrifidus spore/pollen zones) of the mungaroo formation (Phillips Australian Oil company, 

1980a). the well penetrated 466 m of inferred calcareous ooze and marl of Holocene to late 

cretaceous age without returns, and sampled cretaceous chalk, calcareous claystone and siltstone 

to 1857 m, and a 15 m section of upper Jurassic claystone to 1872 m. this Jurassic claystone was 

unconformably underlain by 23 m of upper triassic (Rheatian) carbonate and claystones 39 m of 

transgressive marine siltstone and sandstone (ascribed to the brigadier formation by crostella 

and barter, 1980) and a thick section of upper-middle triassic deltaic sediments of the mungaroo 

formation (1895-4946 m td). this is the maximum drilled thickness of triassic section on the 

Exmouth Plateau. 

A 22.5 m gas column was discovered in upper triassic sandstones (1911-1933 mKb; brigadier 

formation) with reserves of about 0.15 tcf (4 bcm; Walker, 2007). this accumulation has a strong 

flat-spot dHi on seismic data, which indicates the spill-point of the gas into the bounding fault and 

venting through to a gas-chimney evident on seismic (barber, 1988). 


scarborough 1 (1979) 

scarborough 1 was drilled by Esso Australia ltd to test a large, low relief anticline within the barrow 

Group delta that displayed a prominent flat-lying bright spot conforming to the crest of the structure 

(EssO Australia ltd, 1980b). the well was drilled in a water depth of 912 m and was abandoned 

at a td of 2364 mKb due to mechanical problems. it penetrated an upper campanian-Hauterivian 

marl and claystone succession overlying pro-delta claystone (upper delta sequence) and prograding 

submarine fan sandstone (lower delta sequence) of the lower cretaceous barrow Group (total 

683 m thick). drilling was abandoned within the barrow Group, and the underlying triassic section 

was not reached. 

scarborough 1 discovered a 59 m gas column within good quality sands (average 23% porosity) of 

the lower barrow Group basin floor fan sealed by prodelta claystone. formation testing at 1904.5 m 

recovered 5.2 m 3 of methane with only 0.12% ethane and no fractions heavier than propane. 

Additional appraisal wells scarborough 2 (1996, 1997) and scarborough 3, 4 and 5 (2004-2005) 

have since been drilled. Scarborough 2 was drilled to a total depth of 2068 m with the objective to 

appraise the southeast limit of the lower delta fan reservoir discovery, and to confirm the presence 

of higher gas-bearing sands in the upper delta fan with seismic amplitude anomalies (EssO Australia 

ltd, 1997). A total of 84 m of conventional core were cut in the upper and lower fans, and both 

successions were confirmed to be gas bearing from log analysis, mdt samples and production 

testing. the upper fan reservoir contained a 39 m gross gas interval with lower than expected 

porosity (20%), permeability (

High quality reservoirs were encountered in the deeper parts of the mungaroo formation, but 

only poor quality reservoirs (thin argillaceous sandstones and interbedded siltstone and shale) 

occur in the uppermost part of the tilted fault blocks that are in the zone of potential drape closure 

entrapment. Only minor hydrocarbon indications were reported in this interval and wireline logs 

indicated no productive hydrocarbon zones and high water saturations. High mud gas readings 

(generally 5000–10000 ppm, mainly methane but with minor ethane and propane) were recorded 

while drilling the Albian to Rhaetian interval 2140–2467 m. 

eendracht 1 (1980) 

Eendracht 1 was drilled by Esso Australia ltd to test upper triassic (pre-Rhaetian) reservoirs within 

an elongate tilted horst bounded to the west by a major normal fault (Esso Australia ltd, 1981). the 

well was drilled in a water depth of 1354 m and reached a td of 3410 mKb within the mungaroo 

formation. it penetrated Paleocene to Albian calcilutites to 2184.5 m, a thin barremian-Hauterivian 

claystone (muderong shale equivalent) to 2195 m, lower cretaceous prodelta siltstone and 

claystone (barrow Group) to 2344.5 m, a condensed section of upper to lower Jurassic claystone 

(dingo claystone equivalent), upper triassic (Rhaetian) marl to 2419 m, and upper triassic shallow 

marine to deltaic siltstone, claystone and sandstone of the mungaroo formation. 

four gas-bearing sandstones in the triassic mungaroo formation were intersected over the interval 

2467-2652 mKb, with a total net gas pay of 25.5 m. the maximum observed gas column was 44 m 

for a thin sandstone at 2467 m; the three deeper gas sands were recognised pre-drill as seismic 

amplitude anomalies. 

chandon 1(2006) 

chandon 1 was drilled by chevron Australia Pty ltd in 1200 m water depth to a td of 3124 mRt, 

and is located 31 km northwest of the Jansz 2 well. unlike the Jansz-io accumulation, the objective 

was a triassic fault block, and a 197 m gross gas column was intersected in high quality mungaroo 

formation sandstones (Jonasson, 2007). the chandon accumulation has been estimated to contain 

up to 4 tcf (113 bcm) gas (blevin, 2007). detailed results of the well have not yet been released. 

thebe 1 (2007) and thebe 2 (2008) 

thebe 1 was drilled by bHP billiton about 50 km north of the scarborough gas field in 1173 m water 

depth. the well discovered a 73 m gas column (bHP billiton, 2007) in a triassic fault block that may 

contain 2-3 tcf (57–85 bcm) of gas (Anonymous, 2007). thebe 2 was drilled 16 km to the north of 

the initial discovery and confirmed expectations of the size and quality of the thebe resource (bHP 

billiton, 2008a). detailed results of the wells have not yet been released. 

belIcoso 1 (2007) 

belicoso 1, the most northerly exploration well on the Exmouth Plateau (about 81 km north of 

mercury 1) was drilled by Woodside Petroleum ltd in over 1400 m water depth to test a northnortheast 

trending triassic horst (Woodside, 2007a). the well did not encounter hydrocarbons, but 

intersected thick, high-quality reservoirs (Woodside, 2007b). detailed results of the well have not yet 

been released. 

Martell 1 (2009) 

martell 1 was drilled by Woodside Petroleum ltd in 1290 m water depth about 27 km northeast 

of chandon 1. Pressure testing of sandstones over an interval 2778 to 3201 mmdRt confirmed a 

gross gas column of about 110 m and the presence of a gas-water contact (Woodside, 2009a). the 

accumulation occurs within a top triassic horst (Woodside, 2009b). detailed results of the well have 

not yet been released. 

KentIsh KnocK 1 (2009) 

Kentish Knock 1, located about 41 km southwest of thebe 1, was drilled by chevron Australia Pty 

ltd in approximately 1200 m water depth to a td of 2525 mRt. the well discovered 34 m of net gas 

pay (chevron Australia, 2009b). 


table 1: Wells listing 

Well Operator year total depth Hydrocarbons 

belicoso 1 Woodside Energy ltd 2007 2573 mRt not classified 

chandon 1 chevron (tAPl) Pty ltd 2006 3124 mRt Gas 

Eendracht 1 Esso Australia ltd 1980 3410 mKb Gas 

Guardian 1 chevron Australia Pty ltd 2009 3315 mRt not classified 

investigator 1 

(Esso) 

Jupiter 1 

(Phillips) 

Esso Australia limited 1979 3745.6 mKb minor gas 

Phillips Australian Oil company 1979 4946 mRt Gas 

Kentish Knock 1 chevron Australia Pty ltd 2009 2525 mRt Gas 

martell 1 Woodside Petroleum ltd 2009 3300 mRt Gas 

mercury 1 

(Phillips) 

Phillips Australian Oil company 1979 3812 mRt dry 

OdP 762A texas A and m university 1988 1380.8 mRt not classified 

OdP 762c texas A and m university 1988 2311.4 mRt not classified 

scarborough 1 

(Esso) 

Esso Australia ltd. 1979 2360 mKb Gas 

scarborough 2 Esso Australia ltd 1996 2068 mKb not classified 

scarborough 3 bHP billiton Petroleum Pty. ltd. 2005 2122 mRt not classified 

scarborough 3 

cH1 

bHP billiton Petroleum Pty. ltd. 2005 1964 mRt not classified 

scarborough 4 bHP billiton Petroleum Pty. ltd. 2005 1639 mRt not classified 

scarborough 4A bHP billiton Petroleum Pty. ltd. 2005 2055 mRt not classified 

scarborough 5 

thebe 1 

thebe 1 cH 

bHP billiton Petroleum (north West 

shelf) Pty ltd 

bHP billiton Petroleum (Australia) 

Pty ltd 

bHP billiton Petroleum (Australia) 

Pty ltd 

2005 2000 mRt not classified 

2007 2510 mRt Gas 

2007 2450 mRt not classified 

thebe 2 bHP billiton Petroleum Pty ltd 2008 2550 mRt not classified 

thebe 2 cH1 bHP billiton Petroleum Pty ltd 2008 2450 mRt not classified 

Rig Release year shown. Orange shaded areas highlight those wells for which complete data sets are 

not available as at 11 december 2009. note: Wells drilled after 11 december 2009 are not listed. 


Seismic Coverage 

The Release Areas are covered by regional 2D seismic grids acquired in the late 1970s (approximate 

5 km line spacings) and subsequent regional grids acquired in 1995 and 2000 (line spacings of 

about 10–20 km). The southern portion of Release Area W10-22 is also covered by a detailed 1995 

survey (X95A Scarborough; line spacing about 1–2.5 km) that extends across the Scarborough 

Retention Lease WA-1-R to the south. The 2004 Scarborough 3D seismic survey also extends into the 

southwest corner of Release Area W10-22. Deep seismic data was acquired by Geoscience Australia 

in 1991–1995 across the central and northern Exmouth Plateau (Surveys 101, 110, 128; Geoscience 

Australia 2001), and across the outer margins of the Plateau (Surveys 135, 162; Stagg et al, 2004). 

BHP Billiton acquired the HEX07B 3D seismic survey in 2007 and Western Geco acquired the 

Keystone multi-client 3D survey in 2008, both of which cover portion of the original WA-346-P permit 

and the current Release Areas. In 2008, a new multi-client survey (PGS New Dawn) was acquired 

across the Exmouth Plateau including a few lines over the Release Areas (Petroleum Geo-Services, 

2009). 

Seismic data are generally of high quality across the Exmouth Plateau, and indications of gas charge 

and gas-water contacts can commonly be directly imaged as amplitude anomalies and flat-spots. 

Other data 

In addition to commercial petroleum exploration efforts on the Exmouth Plateau, there have also 

been scientific investigations. In 1988, the Ocean Drilling Program, ODP Leg 122 (Haq et al, 1990; 

von Rad et al, 1992b) drilled wells in two locations on the western Exmouth Plateau (Figure 1) and 

four locations on the northern Exmouth Plateau (Wombat Plateau). Detailed descriptions of the fully 

cored holes and the interpretation of the results are given by von Rad et al (1992b). 


petroleum systems ANd hydroCArBoN poteNtiAl 

table 2: petroleum systems elements summary 

Sources • triassic mungaroo formation (gas-prone) 

Reservoirs 

Seals 

Play Types 

• lower cretaceous barrow Group (basin floor fans, turbidites) 

• Oxfordian Jansz sandstone (upper-lower shoreface) 

• upper triassic (Rhaetian) reefs (no discoveries to date) 

• upper triassic brigadier formation (shallow marine-deltaic) 

• top triassic mungaroo formation (fluvio-deltaic) 

• intra-triassic mungaroo formation (fluvio-deltaic) 

• lower cretaceous marine muderong shale (regional seal) 

• lower cretaceous distal condensed claystones, barrow Group 

• Jurassic condensed marls/claystones (dingo claystone equivalents) 

• intra-formational mungaroo formation claystones (cross-fault) 

• tilted triassic fault blocks and associated drapes 

• Oxfordian shoreface sandstone stratigraphic traps 

• lower cretaceous basin floor fan stratigraphic traps 

• upper triassic (Rhaetian) Pinnacle reefs (not tested) 

the super-giant Jansz-io gas field, giant scarborough gas field, and the Jupiter 1 and Eendracht 1 

gas discoveries, together with the recent gas discoveries in the chandon 1, thebe 1 and 2, martell 1, 

Glencoe 1, nimblefoot 1, briseis 1 and Kentish Knock 1 wells, demonstrate that the deepwater 

central Exmouth Plateau is prospective for large gas discoveries. All these discoveries are attributed 

to a widespread regional gas system sourced from the triassic succession. 

source rocKs 

the thick triassic and older sedimentary section on the Exmouth Plateau has the greatest potential 

for mature source facies, with possible organic-rich units in the lower triassic (marine locker shale 

equivalents) and upper triassic (deltaic mungaroo formation facies and marine equivalents). Recent 

exploration activities on the Exmouth Plateau are based on a model that invokes gas charge from the 

deeply buried coal and carbonaceous claystone of the mungaroo formation. Peak gas generation 

from these triassic source rocks is interpreted to occur now at depths greater than 5 km subsea 

(bussell et al, 2001). 

Organic-rich sediments may also be present within the condensed Jurassic and upper cretaceous 

succession, but these are immature. 

reservoIrs 

fluvio-deltaic sandstones of the upper triassic mungaroo formation (eg Eendracht, thebe, martell 

and chandon) and basin-floor fan and turbidite sandstones of the lower cretaceous barrow Group 

(eg scarborough, nimblefoot and brieseis shallow) provide good quality reservoirs across the 

central Exmouth Plateau and are likely to represent the main reservoir target within the release 

areas. transgressive marine sandstones of the brigadier formation (eg Jupiter) and Rhaetian reefal 

carbonates provide additional potential reservoir targets. 


SealS 

Fine-grained deepwater Cretaceous sediments (Muderong Shale and distal facies of the Barrow 

Group) provide a regional seal across the Exmouth Plateau. There are also intra-formational seals 

within the deltaic sequences of the Upper Triassic Mungaroo Formation. The Rhaetian marl and 

Jurassic condensed marls/claystones (Dingo Claystone equivalents), where preserved, can also 

provide a top seal to Triassic reservoirs. 

Play Types 

High relief top Triassic fault blocks together with associated drape features and deeper intra- 

Triassic cross-fault traps provide numerous potential structural traps on the central Exmouth Plateau 

(Figure 7). Upper Triassic (Rhaetian) pinnacle and patch reefs (such as those intersected in the ODP 

holes on the Wombat Plateau on the northern margin of the Exmouth Plateau; Williamson et al, 

1989) have also recently been identified on new 3D data across parts of the central Exmouth Plateau, 

and represent a potential new play in the region that has yet to be tested. Other proven stratigraphic 

traps in the region include Lower Cretaceous basin floor fans (eg Scarborough) and Upper Jurassic 

shoreface sandstones (eg Jansz-Io, Glencoe), but the later are unlikely to extend as far west as the 

current release areas. 

Critical Risks 

Given that a proven hydrocarbon system has already been established across the central Exmouth 

Plateau, continued success relies on the identification of additional valid traps with access to charge 

from the gas-prone Mungaroo source. 3D seismic and AVO technology are thus key exploration tools 

that are likely to contribute to continued exploration success on the deepwater Exmouth Plateau 

(Longley et al, 2002; Korn et al, 2003; Williamson and Kroh, 2007). 


WA 

NT 

SA 

TAS 

QLD 

NSW 

VIC 

WA-364-P 

ODP 762A, C 

Eendracht 1 

WA-366-P 

WA-386-P 

Kentish Knock 1 

2000 

W10-20 

WA-365-P 

Scarborough 

1000 

WA-367-P 

Thebe 1 

Guardian 1 

Investigator 1 

113° 

0 50 km 

Thebe 2 CH1 

WA-346-P 

W10-22 

WA-348-P 


Jupiter 1 

Yellowglen 1 

WA-268-P 

Bravo 1 

Rimfire 1 

Briseis 1 

Glencoe 1 Dunlop 1 

WA-383-P 

Nimblefoot 1 

Lightfinger 1 

Hijinx 1 

WA-390-P 

Mentorc 1 

WA-351-P 

WA-401-P 

Mercury 1 

Belicoso 1 

Toporoa 1 

Warrior 1 

Chandon 1 

114° 

WA-347-P 


WA-392-P 

WA-404-P 

WA-374-P 

Satyr 1 

Martell 

1 

Io/Jansz 

Achilles 

1 

Where well symbol information is sourced from publicly available "open file" data, it has been provided by Geoscience Australia from Well Completion Reports. These symbols were generated from open file 

data as at 11 December 2009. Where well symbol information is not publicly available from titleholders' data, the information has been extracted from other public sources. Field outlines are 

provided by 

GPinfo, an Encom Petroleum Information Pty Ltd product. Field outlines in GPinfo are sourced, where possible, from the operators of the fields only. Outlines are updated at irregular intervals 

but with at 

least one major update per year. 

2010 Offshore Petroleum 

Acreage Release Area 

Existing petroleum title 

Gas field 


Gas pipeline (proposed) 

Bathymetry contour (depth in metres) 

Stratigraphic well 

Petroleum exploration well - Not classified 

Petroleum exploration well - Dry hole 

Petroleum exploration well - Gas show 

Petroleum exploration well - Gas discovery 

Figure 1. Location map of Release Areas W10-20, W10-21 and W10-22, 

Exmouth Plateau, Carnarvon Basin. 

1000 

19° 

20° 

Orthrus 

09-4254-1 

WA-387-P 

WA-387-P 

WA-269-P 

Eurytion 

Geryon 

Chrysaor 

Clio 1 

500 

Ixion 1 

Bellatr 

Saturn 

Dion 

W09 

Bluebel 

Gorgon 

200

MAP SHEET 

SE 49 

2010 Release Areas 

Exmouth Plateau, Carnarvon Basin 

Western Australia 


(2 blocks, approx 160 km 2 ) 

113°00'04.73"E 

19°09'55.31"S 

19°19'55.32"S 

113°00'04.74"E 

2797 

2869 

19°39'55.33"S 

113°05'04.75"E 

113°15'04.73"E 

19°09'55.31"S 

113°05'04.73"E 

19°09'55.31"S 2800 

19°19'55.32"S 

113°05'04.74"E 

113°05'04.75"E 

19°29'55.32"S 

3086 

3158 

19°14'55.31"S 

113°15'04.74"E 

113°15'04.74"E 

19°24'55.31"S 

3016 

2873 

2945 



19°39'55.32"S 

113°25'04.75"E 

19°24'55.31"S 

113°30'04.74"E 

For convenience, geographical coordinates shown on this map are expressed in terms of the Geocentric Datum 

of Australia 1994 (GDA94). Permit areas are defined by the 5 minute graticular block system set out under 

Section 33 of the Offshore Petroleum and Greenhouse Gas Storage Act 2006; under Sections 37 and 38 of the 

Act, the position of those blocks is determined by reference to the Australian Geodetic Datum (AGD66). 


113°45'04.73"E 

19°09'55.29"S 

19°19'55.30"S 

113°45'04.74"E 


IDEAS 9155-12

GRATICULAR BLOCK LISTING 

Release Area W10-20 

Exmouth Plateau, Carnarvon Basin, Western Australia 

Map Sheet SE 49 

2797 2869 

Assessed to contain 2 full blocks 

Release Area W10-21 



2800 2801 2802 2803 2804 2805 

2873 2874 2875 2876 2877 2945 

2946 

Assessed to contain 13 full blocks 

Release Area W10-22 



3016 3017 3086 3087 3088 3089 

3158 3159 3160 3161 

Assessed to contain 10 full blocks

WA 

NT 

SA 

TAS 

QLD 

NSW 

VIC 

110/15 

Eendracht 1 

Vinck 1 

112° 

0 

Kentish Knock 1 

Thebe 2 CH1 


ODP 762A, C Scarborough 

ODP 762B 

ODP 763A-C 


Investigator 

Sub-basin 

Sirius 1 


Thebe 1 


Jacala 1 

Figure 5 

Yellowglen 1 

Bravo 

1 Glencoe 1 Briseis 1 

Rimfire 

1 

Nimblefoot 

1 

Dunlop 1 

Lightfinger 1 

Hijinx 1 

Warrior 1 

Mentorc 1 


Toporoa 1 

Leyden 1B ST1 

Belicoso 1 

Mercury 1 

Jupiter 1 


Martell 1 

Exmouth 

Plateau 

Clio 2 

Satyr 1 

Lauda 1 

Ixion 1 

Io/Jansz 

Saturn 1 

Eurytion 

Maenad 

Geryon 


Dionysus 

Orthrus 

Achilles 1 

Clio 1 

Chrysaor 

Bluebell 1 

Gorgon 

Euryale 1 

Zeepaard 1 ST1 

Spar 

114° 

18° 

Antiope 1 ST1 

Altair 1 

Woollybutt 

Where well symbol information is sourced from publicly available "open file" data, it has been provided by Geoscience 

Australia from Well Completion Reports. These symbols were generated from open file 

data as at 11 December 2009. Where well symbol information is not publicly available from titleholders' data, the 

information has been extracted from other public sources. Field outlines are provided by 

GPinfo, an Encom Petroleum Information Pty Ltd product. Field outlines in GPinfo are sourced, where possible, from the operators of the fields only. Outlines are updated at irregular intervals but with at 

least one major update per year. 



Gas field 

Oil field 

Seismic cross section location 

Basin boundary 

Sub-basin boundary 

Fault 

Syncline 

NORTHERN CARNARVON BASIN 

Figure 3. Structural elements of the Exmouth Plateau showing 2010 Release Areas and 

location of seismic section shown in Figure 5. 

100 km 

Petroleum exploration well - Dry hole 

Petroleum exploration well - Gas show 

Petroleum exploration well - Gas discovery 

Petroleum exploration well - Oil discovery 

09-4254-3 

Stratigraphic well Barrow 

P 

Petroleum exploration well - Not classified Sub-basin 

Petroleum exploration well - Gas discovery and oil show 

Rankin P 

Corkybark 1A 11A 

ST1

AGE 

(Ma) 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

110 

120 

130 

140 

150 

160 

170 

180 

190 


210 

220 

230 

Triassic Jurassic Cretaceous Paleogene Neogene 

Figure 4. 

Period Epoch Stage 

Quaternary 

Holocene 

Pleistocene 

Pliocene 

Miocene 

Oligocene 

Eocene 

Paleocene 

Late 

Early 

Late 

Middle 

Early 

Late 

Tarantian 

Ionian 

Calabrian 

Gelasian 

Piacenzian 

Zanclean 

Messinian 

Tortonian 

Serravallian 

Langhian 

Burdigalian 

Aquitanian 

Chattian 

Rupelian 

Priabonian 

Bartonian 

Lutetian 

Ypresian 

Thanetian 

Selandian 

Danian 

Maastrichtian 

Campanian 

Santonian 

Coniacian 

Turonian 

Cenomanian 

Albian 

Aptian 

Barremian 

Hauterivian 

Valanginian 

Berriasian 

Tithonian 

Kimmeridgian 

Oxfordian 

Callovian 

Bathonian 

Bajocian 

Aalenian 

Toarcian 

Pliensbachian 

Sinemurian 

Hettangian 

Rhaetian 

Norian 

Carnian 

Middle Ladinian 

Exmouth Plateau stratigraphy 

Delambre Formation 

Trealla Limestone 

Mandu Formation 

Walcott Formation 

Wilcox Formation 

Dockerell Formation 

Lambert Formation 

Miria Formation 

Toolonga Calcilutite 

Gearle Siltstone 

Windalia Radiolarite 

Muderong Shale 

Undifferentiated 

Barrow Group 

Dingo Claystone 

Janz Sandstone 

Athol Formation 

Murat Siltstone 

Brigadier Formation 

Mungaroo Formation 

Cape Range Group 

Guilford 1 

Hydrocarbon shows 

Briseis 1, Leyden 1BST1 

Nimblefoot 1, Scarborough 1 


Geryon 1, Io 1, Maenad 1, Saturn 1 

Glencoe 1, Jansz 1, Jansz 3 

Callirhoe 1, Geryon 1, Jupiter 1, Zeewulf 1 

Saturn 1 


Briseis 1, Callirhoe 1, Chandon 1, Clio 1, Eendracht 1, 

Geryon 1, Maenad 1A, Martell 1, Orthrus 1, 

Resolution 1 ST1, Sirius 1,Thebe 1, Urania 1, Vinck 1, 


Generalised stratigraphy of the Exmouth Plateau, tied to the geological timescale after 

Gradstein et al (2004) and Ogg et al (2008). 

09-4254-2

Two-way time (s) 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

NW SE 

Jupiter 1 

Base 

Cretaceous 

Base Jurassic - 

Top Triassic 

Intra-Triassic 

Intra-Triassic 

Valanginian 

Callovian 

Aptian 

Top Top Permian Permian 

Turonian 


Exmouth Plateau 

Base Cenozoic 

0 25 km 

Base Eocene 


Mid. Oligocene 

Late Late Carboniferous 

Carboniferous 

Basement Basement 

Late Miocene 

Line 110/15 09-4254-4 

Figure 5. Geoscience Australia seismic line 110/15 across the central and outer Exmouth Plateau. 

Intrusives Intrusives

WA 

NT 

SA 

TAS 

QLD 

NSW 

VIC 

112° 

Eendracht 

Vinck 

Kentish Knock 


Scarborough 

Sirius 

Thebe 



Jupiter 

Nimblefoot 

Glencoe 

0 100 km 

Chandon 

Briseis 

114° 

Zeepaard 

Martell 

Io/Jansz 

Clio 

Gorgon 

Saturn 

Eurytion 

Geryon 

Dionysus 


Maenad 

Orthrus Chrysaor 

Spar 

East Spar 

Lauda 

Woollybutt 

Field outlines are provided by GPinfo, an Encom Petroleum Information Pty Ltd product. Field outlines in GPinfo are sourced, where possible, from the operators of the fields only. Outlines are updated at 

irregular intervals but with at least one major update per year. 



Existing petroleum title 

Barremian 

Reservoir Age (Formation) 

Valanginian and Berriasian 

Tithonian, Oxfordian and Middle Jurassic 

Late Triassic (Brigadier and Mungaroo 

formations) 

Oil accumulation Gas accumulation 

Figure 6. Major oil and gas accumulations on the Exmouth Plateau indicating age of 

main reservoir. 

18° 

09-4254-5

Top Triassic 

Fields: Briseis (deep), Chandon, Eendracht, Goodwyn, Gorgon, 

Jupiter, Martell, N.Rankin, Pluto, Wheatstone 

Deep Triassic 

Fields: Clio, Goodwyn-H, Urania 

Sea floor 

NOT TO SCALE 

Cretaceous/Jurassic 

Fields: Glencoe, Janz-Io 

Cenozoic 

Cretaceous 

Carbonate pinnacle reefs 

No fields drilled to date 

Recently identified on new 3D 

Jurassic Triassic 

Figure 7. Play types on the Exmouth Plateau (modified from Woodside, 2009b). Lower Cretaceous Barrow Group basin floor fan and 

turbidite plays (eg Scarborough, Nimblefoot and Briseis shallow) not shown. 

09-4254-6

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