V I F M & P V I F M & P

VMPi

VIICTORIAN NITIATIVE FMOR INERALS &P ETROLEUM

HYDROCARBON P ROSPECTIVITY P ACKAGE F OR VIC/O-01(1), VIC/O-01(2) andVIC/O-01(3) , E ASTERN O NSHORE O TWAY B ASIN, VAICTORIA, USTRALIA: 2001 ACREAGE R ELEASE

VIMP REPORT70

A.E. CONSTANTINE N. LIBERMAN

November 2001

KYNETON

PEP160 BALLARAT AREA OF INTEREST

HAMILTON MELBOURNE

PEP151 PEP150 LARA

PEP159 GEELONG VIC/O-01(1) VIC/O-01(3) PEP152 (b) COBDEN 200m COLAC PORTLAND PEP154(a) VIC/P46 1000m PEP153

VIC/O-01(2) VIC/P44 2000m

3000m VIC/P43

0 10 20 30 40 50

4000m

2001 acreage release . VIMP Report 70

Hydrocarbon prospectivity package for VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3), Eastern Onshore Otway Basin, Victoria, Australia 2001 Acreage Release

A. Constantine and N. Liberman

November 2001 Bibliographic reference: CONSTANTINE, A. and LIBERMAN, N., 2001. Hydrocarbon Prospectivity Package for VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3), Eastern Onshore Otway Basin, Victoria, Australia. 2001 Acreage Release. Victorian Initiative for Minerals and Petroleum Report 70. Department of Natural Resources and Environment.

ISSN 1323 4536 ISBN 0 7306 9472 0 (Hard Copy) ISBN 0 7306 9473 9 (CD-ROM)

This report may be purchased from: Business Centre Minerals & Petroleum Department of Natural Resources and Environment 8th Floor, 240 Victoria Parade East Melbourne, Victoria 3002, Australia

For further technical information contact: Manager Petroleum Development Department of Natural Resources and Environment PO Box 500 East Melbourne, Victoria 3002, Australia Website: www.nre.vic.gov.au/minpet/index.htm

Authorship and Acknowledgments: The package was compiled and collated by the Basin Studies Group of the Petroleum Development Unit. The authors would like to acknowledge the following Petroleum Development Unit staff members for their assistance in the production of this report: David Wong, Eddie Frankel, Mike Woollands, Jim Driscoll and Laiyee Mok.

Disclaimer: This publication may be of assistance to you but the authors and the State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.

PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 1

Contents Executive Summary 4 1 Introduction 5 2 Exploration History 10 3 Basin Development 13 4 Structural Elements 15 4.1 Late Jurassic – Early Cretaceous (Tithonian – Barremian) 15 Gellibrand Trough 15 Ombersely Trough 15 Armytage High 15 Stoneyford High 15 4.2 Mid-Cretaceous 15 Otway Uplift 15 Warracbarunah Uplift 15 4.3 Upper Late Cretaceous – Tertiary 15 Colac Trough 15 Barwon Downs Graben 16 Anglesea Embayment 16 Torquay Sub-basin 16 Sorrento Graben 16 4.4 Late Tertiary (Late Miocene – Pliocene) 16 Otway Ranges 16 Barongarook High 16 Barrabool Hills 16 Paraparap High 16 Bellarine High 17 5 Stratigraphy 23 5.1 Otway Group 23 5.2 Sherbrook Group 23 5.3 Wangerrip Group/Eastern View Group 27 Wangerrip Group 27 Eastern View Group 27 5.4 Nirranda Group/Demons Bluff Group 29 Nirranda Group 29 Demons Bluff Group 29 5.5 Heytesbury Group/Torquay Group 29 Heytesbury Group 29-30 Torquay Group 30 5.6 Older Volcanics 30 5.7 Newer Volcanics 30 6Seismic Data 31 6.1 Seismic Coverage 31 VIC/O-01(1) 31 VIC/O-01(2) 31 VIC/O-01(3) 31 6.2 Seismic Interpretation and Mapping 32 TWT Structure Maps 32 Interpreted Seismic Sections 32 7 Other Geophysical Data 33 7.1 Gravity 33 7.2 Magnetics 33-34 2 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

8 Petroleum Systems 35 8.1 Casterton Formation – Pretty Hill Formation 35 8.2 Eumeralla Formation 35-36 9 Maturation History 38 10 Play Fairways and Play Types 41 10.1 Fractured Basement 41 10.2 Pretty Hill Formation 41 10.3 Intra-Eumeralla Formation 43 Heathfield Sandstone 43 Barwon River Member 43 10.4 Base Tertiary 45 Pebble Point Formation 45 Moomowroong Sand – Wiridjil Gravel 45 Eastern View Formation 45 11 Summary 47 11.1 VIC/O-01(1) 47 11.2 VIC/O-01(2) 47 11.3 VIC/O-01(3) 47-48 12 Natural/Cultural Environments and Regulations 49 12.1 Primary Petroleum Legislation 49 12.2 Access to land 49 Open-File Reports available from MPV 50-52 CD-ROM Data Packages available from MPV 53 References 54-57 MPV Contacts 58 Victorian Initiative for Minerals and Petroleum (VIMP) report series 59-60

List of Figures 1. Petroleum exploration wells in and around VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3). Seismic 7 lines in the three blocks are coloured grey. A – A’ is the location of the schematic regional cross-section illustrated in Figure 5. 2. Pipeline infrastructure. 8 3. Geological maps issued by Geological Survey of Victoria covering the Eastern Otway Basin. 9 4. Tectonic history of the Otway Basin (from Geary & Reid, 1998). 14 5. Regional cross-section across the Eastern Otway Basin (modified from Messent et al., 1999). 18 6. Late Jurassic – Early Cretaceous (Tithonian – Barremian) structural elements in VIC/O-01(1), 19 VIC/O-01(2) and VIC/O-01(3). Colour-fill grid is a TWT structure map of Top Basement. 7. Mid-Cretaceous denudation map for the Eastern Otway Basin (modified from Cooper & Hill, 1997). 20 Contour values in metres. 8. Surface structure map of the Eastern Otway Basin showing the main Late Cretaceous – Tertiary 21 depocentres and key Late Miocene – Pliocene faults, monoclines, anticlines and synclines. 9. Late Miocene – Pliocene denudation map for the Eastern Otway Basin (modified from 22 Cooper & Hill, 1997). Contour values in metres. 10. Stratigraphy of the Otway Basin. Area covered in this report highlighted in red. 24 11. Simplified geological map of the Barrabool Hills showing the outcrop extent of the Barwon Hills 25 Member and Eumeralla Formation. Photomosaic interpretation below map is a view of the type section from the north side of the Barwon River. 12. Distribution of Sherbrook Group units and Late Cretaceous Eastern View Group in VIC/O-01(1), 26 VIC/O-01(2) and VIC/O-01(3). 13. Distribution of Wangerrip Group units and Early Tertiary Eastern View Group sediments in 28 VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3). 14. Outcrop – subcrop maturity (Rvmax%) map for the top of the Eumeralla Formation in the Eastern 36 Otway Basin. Otway Ranges data from Cooper et al. (1993) and Cooper (1995a). Areas of Mid-Cretaceous uplift and erosion overlain for comparison. 15. Source rock potential of the Eumeralla Formation in Stoneyford-1, Tirrengowa-1 and 37 Warracbarunah-2. PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 3

16. Burial history models for Location A in the Barwon Downs Graben (from Aburas & Boult, 2000). 39 Note slight increase in the maturity of the Eumeralla Formation during the Late Tertiary in Model 1. 17. Palynological map of the Eastern Otway Basin showing the outcrop – subcrop age of the 40 Eumeralla Formation. Areas of Mid-Cretaceous uplift and erosion overlain for comparison. From Constantine (2001). 18. Fractured basement and Pretty Hill Formation play fairway map. Prospective areas highlighted 42 in yellow. 19. Intra-Eumeralla Formation play fairway map. Prospective areas highlighted in yellow. 44 20. Base Tertiary play fairway map. Prospective areas highlighted in yellow. 46

List of Enclosures 1. Topography of VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3) 2. Well summary sheet: Anglesea-1 3. Well summary sheet: Hindhaugh Creek-1 4. Well summary sheet: Olangolah-1 5. Well summary sheet: Stoneyford-1 6. Well summary sheet: Tirrengowa-1 7. Well summary sheet: Nalangil-1 8. Well summary sheet: Ingleby-1 9. Well summary sheet: Warracbarunah-2 10. Well summary sheet: Irrewarra-1 11. Seismic coverage VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3) 12. SEGY coverage VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3) 13. Top Basement Time Structure Map, VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3) 14. Top Eumeralla Formation Time Structure Map, VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3) 15. Interpreted composite seismic sections 16. Bouguer gravity VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3) 17. Aeromagnetic coverage VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3): First Vertical Derivative (histogram equalised) 18. Land Use Map: VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3) 4 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

Executive summary The three blocks on offer this year have been explored in the past by a number of companies who sunk a total of twenty one wells without encountering any significant hydrocarbon shows or accumulations. This In September 1998, a major fire at the Longford lack of success, however, is not considered a true processing plant in East Gippsland left Melbourne reflection of the prospectivity of the area because the with only two weeks emergency supply of gas. This majority of wells were sunk well before the first incident brought home the vulnerability of the gas seismic lines were acquired in 1960 and were not valid system due to its reliance on the Gippsland Basin, and structural tests. The first fourteen wells were spudded has led many petroleum exploration companies to between 1923 and 1948 (Anglesea-1, -2; Torquay-1, -2, re-evaluate the neighbouring Otway Basin which has -3, -4, -5, -6, -7; Geelong Oil Flow-1), followed by two long been thought to have little potential. This view, more in 1962 (Anglesea-1A) and 1970 (Hindhaugh however, has now been finally laid to rest with the Creek-1), and a further seven between 1982 and 1996 recent discovery by SANTOS of five onshore gas fields (Olangolah-1, Stoneyford-1, Tirrengowa-1, Nalangil-1, at Port Campbell and two large (500 BCF – 1 TCF Ingleby-1, Warracbarunah-2, Irrewarra-1). The first GIP) offshore gas fields to the south by an Origin sixteen are all located in a small corner of the basin Energy - Woodside Energy led joint venture. near Anglesea. Anglesea-1 and -2, Torquay-1, -2, -3, In light of these discoveries, the State of Victoria has -4, -5, -6 and –7, and Geelong Oil Flow-1 were all decided to release the following three blocks in the shallow (< 625 m deep) wells but none were valid onshore Eastern Otway Basin for work programme structural tests. Anglesea-1A and Hindhaugh Creek-1 bidding: VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3) were deep wells (2371 to 3068 m deep) but neither was (see Fig. 1 for location). The three blocks cover a located on valid structures due to poor seismic control. combined area of 5473 km2 and are located The other seven wells are all located in the west of the approximately 100 km southwest of the City of area near Colac except Olangolah-1, which is located Melbourne (population 3,680,000), the state capital of on the crest of the Otway Ranges. Of the seven, only Victoria. Examination of geological and seismic data Stoneyford-1, Tirrengowa-1, Nalangil-1, Ingleby-1 and from VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3) Irrewarra-1 were valid structural tests. These wells suggests that parts of these blocks may have good are thought to have failed because they are located in hydrocarbon potential as they possess many of the areas of significant Mid-Cretaceous uplift and erosion, prerequisites necessary for successful exploration and either leaked in response to the uplift including mature source rocks, good reservoir – seal (eg. Stoneyford-1, Tirrengowa-1) or lacked access to pairs, and numerous potential structural and charge from Tertiary kitchens (eg. Nalangil-1, stratigraphic traps. Four major play types are Ingleby-1, Irrewarra-1). The other two wells, recognised: Olangolah-1 and Warracbarunah-2, were stratigraphic tests. 1) Palaeozoic fractured basement; 2) Lower Cretaceous Pretty Hill Formation tilted fault blocks and faulted anticlines; 3) Intra-Eumeralla Formation (Heathfield Sandstone & Barwon River Member) up-dip pinchouts and anticlines; and 4) Late Miocene – Pliocene anticlines with Palaeocene (Pebble Point Formation, Moomowroong Sand, Wiridjil Gravel) and Eocene (Eastern View Formation) objectives. Geochemical data indicate three units have significant source rock potential in the three blocks: the Late Jurassic – Early Cretaceous Casterton, Pretty Hill and Eumeralla formations. The first two formations have been geochemically identified as the source of gas and condensate onshore in the Pretty Hill Formation to the west of the study area in the Penola Trough (South Australia), while the latter has been identified as the source of gas onshore in the Waarre Formation at Port Campbell to the southwest of the study area. Vitrinite reflectance data indicates these units in the Eastern Otway range from immature for oil to overmature for gas, while maturation studies indicate the main phase of hydrocarbon generation occurred towards the end of the Early Cretaceous, with some possible generation in the Tertiary. PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 5

1 Introduction Portarlington and Sorrento), and one 1:50 000 scale sheet (Colac and part of Beech Forest). The location of these map sheets with respect to VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3) is illustrated in Figure 3. The Otway Basin is one of a series of Late Jurassic - Tertiary basins that developed along the southern The 1:250 000 scale Colac and Queenscliff sheets cover margin of Australia during the break-up of eastern the entire Eastern Otway Basin as far east as the Gondwana. The basin is located in the southeastern Mornington Peninsula. The Colac sheet (Geological corner of the continent and covers an area of Survey of Victoria, 1973) covers most of VIC/O-01(1) c. 155,000 km2, 20% of which is located onshore. It is a and VIC/O-01(2), while the Queenscliff sheet composite basin consisting of an early, non-marine, (Geological Survey of Victoria, 1971) covers all of intra-cratonic rift basin of Late Jurassic - Early VIC/O-01(3) and a small part of VIC/O-01(1) and Cretaceous age, overlain in part by a marginal marine VIC/O-01(2). The geology of these two map sheets is rift basin of Late Cretaceous age, which is in turn summarised in Douglas & Laing (1976) and succeeded by a fully marine basin of Tertiary age. Abele (1977) respectively. The 1:100 000 scale Port Total basin-fill is about 10,000 m. Campbell Embayment sheet (Edwards & Tickell, 1994) covers the southwestern parts of VIC/O-01(1) and The three blocks on offer this year, VIC/O-01(1), VIC/O-01(2). A detailed report accompanying this map VIC/O-01(2) and VIC/O-01(3), are located at the sheet (Tickell et al., 1992) is also available. The eastern end of the Otway Basin, about 50 km 1:63 360 scale Geelong (Geological Survey of Victoria, northeast of the onshore Port Campbell gas fields (see 1963), Anglesea (Geological Survey of Victoria, 1963), Fig. 1). This part of the basin is an area of significant Portarlington (Geological Survey of Victoria, 1977) and vertical relief, ranging from sea-level up to 686 m in Sorrento (Geological Survey of Victoria, 1967) sheets elevation, with a strong NE-oriented structural grain cover all of VIC/O-01(3) and the northeastern corners (see Encl. 1). The principal physiographic features are of VIC/O-01(1) and VIC/O 01(2). The geology of the the Otway Ranges, Barongarook High, Barrabool Geelong and Anglesea sheets is summarised in Hills, Colac Plain and Bellarine Peninsula. The Otway Spencer-Jones (1970) and Abele (1968, 1979) Ranges, Barongarook High and Barrabool Hills are respectively. No explanatory notes were issued for prominent physiographic highs. The Otway Ranges is Portarlington or Sorrento sheets. The 1:50 000 ‘Colac the largest of the three and is over 80 km long and and part of Beech Forest’ sheet (Tickell, 1991a) covers 40 km wide with a sinuous NE-trending axis. It rises the central part of VIC/O-01(1) and a small piece of over 680 m above the adjacent offshore Torquay VIC/O-01(2). A detailed report on the geology of this Sub-basin to the east and is flanked to the northwest map sheet is given in (Tickell et al., 1991). Copies of by the smaller Barongarook High, which rises about these maps and reports can be obtained from the 200 m above the Colac Plains to the north. The Minerals Business Centre (see ‘MPV Contacts’ section Barrabool Hills is a small ENE-WSW striking at the back of this report for contact details). structure approximately 10 km long and 8 km wide located about 20 km to the northeast of the Otway Other GSV reports relevant to this acreage release Ranges. It rises about 100 m above the Colac Plains. include several excursion guides for the Anglesea area (eg. Abele, 1984; Thompson & Link, 1987; Arditto & VIC/O-01(1), the largest of the three blocks on offer Hall, 1994) and Johanna River – Castle Cove area at 2 (2831 km ), encompasses the Colac Plain and the southwestern end of the Otway Ranges (Arditto & Barongarook High, and is bisected by a gas pipeline Hall, 1994), as well as several studies on the geology of which supplies gas from the Port Campbell gas fields the Anglesea area (Abele, 1979) and Bellarine to the Geelong – Melbourne market (see Fig. 2). The Peninsula (Esplan, 1962a, b; Kenley, 1974). second block, VIC/O-01(2), covers an area of about Photocopies of these reports can be obtained from the 2 1586 km and incorporates most of the Otway Ranges. MPV Minerals Library (see ‘MPV Contacts’ section at The third block, VIC/O-01(3), is located to the east of the back of this report for contact details). VIC/O-01(1) and VIC/O-01(2), and covers an area of about 1057 km2. This block encompasses the Numerous papers have also been published in the Barrabool Hills and Bellarine Peninsula. scientific literature on various aspects of the structure of the Eastern Otway Basin (Edwards, 1962; Medwell, The objective of this report is to provide an overview of 1971; Duddy, 1994; Hill et al., 1994; Cooper, 1995a,b; the geology and hydrocarbon prospectivity of the Perincek & Cockshell, 1995; Cooper & Hill, 1997) and onshore Eastern Otway Basin. Its main aims are to its thermal history (Cooper et al., 1993; Duddy, 1994; introduce the reader to what work has already been Cooper & Hill, 1997). Several papers have also been done and what data is open-file. Over the past forty published on the Tertiary stratigraphy and years, a significant amount of geological information biostratigraphy of the Johanna River – Castle Cove has been published on the geology of the Eastern (Carter, 1958; Shafik, 1983; Waghorn, 1989), Torquay Otway Basin. Most of this work has been conducted (Reeckmann, 1994) and Geelong areas (Bowler, 1963). by Geological Survey of Victoria (GSV) who have An excellent summary of the Mesozoic and Tertiary issued eight geological sheets for the area comprising stratigraphy of the Eastern Otway Basin can be found two 1:250 000 scale sheets (Colac and Queenscliff), one in Douglas et al. (1988) and Abele et al. (1988). 1:100 000 scale sheet (Port Campbell Embayment), four 1:63 360 scale sheets (Geelong, Anglesea, 6 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

The Eastern Otway Basin has also been the focus of many university research projects including three Ph.D’s (Duddy, 1983; Felton, 1992; Cooper, 1995a) and two M.Sc’s (Richardson, 1993; Madsen, 2000). Duddy (1983) and Felton (1992) focus on the sedimentology, petrology and geochemistry of the Otway Group, with a strong emphasis on the Eumeralla Formation. Cooper (1995a), on the other hand, investigated the structure and thermochronology of the onshore Eastern Otway Basin and offshore Torquay Sub-basin, combining seismic data with field mapping data and vitrinite/apatite fission track tools to construct balanced sections and estimate uplift/erosion rates. Richardson (1993) looked at the structure and stratigraphy of the Colac area onshore using seismic data, while Madsen (2000) undertook a similar study of the offshore Torquay Embayment and onshore Anglesea area. PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 7

39° S

38° 30' S

38° S

39° S

38° 30' S

38° S

VOIR)

OUTCROP

OTWAY GROUP SEISMIC LINE GAS FIELD (WAARRE FM RESER

144° 30

Y-1 TO -5

144° 30

Y-6&-7

TORQUA

SNAIL-1 coloured grey. A – A’ is the location of the

TORQUA

FLOW-1

NERITA-1

ANGLESEA-1A

HINDHAUGH CREEK-1

GEELONG OIL

ANGLESEA-1

ANGLESEA-2

144° E

WILD DOG-1

144° E

-1

INGLEBY

OTWAY

RANGES

POINT

LEWIS

IRREWARRA-1

WARRACBARUNAH-2

OLANGOLAH-1

NALANGIL-1

143° 30

143° 30 C/O-01(2) and VIC/O-01(3). Seismic lines in the three blocks are

A-1

143° 30

TIRRENGOW

STONEYFORD-1 5.

LOCH ARD-1

ERIC THE RED-1

PURRUMBETE-1

143° E

GAS FIELD

GEOGRAPHE

143° E

GAS FIELDS

PORT CAMPBELL

MINERVA

GAS FIELD

LA BELLA

GAS FIELD

5 Petroleum exploration wells in and around VIC/O-01(1), VI

0 1

39° S

chematic regional cross-section illustrated in Figure

Figure Figure s

38° 30' S

38° 30' S 8 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

143°E 144°E 145°E

Gas pipeline MELBOURNE Oil pipeline

38°S LARA 38°S

VIC/O-01(3) PEP PEP159 VIC/O-01(1) 154b COLAC WARRNAMBOOL PEP153 PEP154a

PPL3 PPL4 PPL5

PPL1 PPL2 VIC/O-01(2) VIC/P44 VIC/ RL8

VIC/ RL7 VIC/P34 39°S EDGE OF OTWAY 39°S BASIN

FORTRUE THE CENTRE NORTH IS OF SHOWN THE MAP 0 8 16 24 32 40

143°E 144°E 145°E

Figure 2 Pipel ine infr a str uctur e . PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 9

143°E 144°E 145°E

38°S 38°S

1 2

1 3 4 1

1 2

39°S 39°S

0 8 16 24 32 40

143°E 144°E 145°E

1 : 50,000 SCALE [1 = COLAC]

1 : 63,360 SCALE [1 = GEELONG ; 2 = PORTARLINGTON; 3 = ANGLESEA ; 4 = SORRENTO]

1 : 100,000 SCALE [1 = PORT CAMPBELL EMBAYMENT]

1 : 250,000 SCALE [1 = COLAC ; 2 = QUEENSCLIFF]

2001 ACREAGE RELEASE AREAS

Figure 3 Geological maps issued by Geological Survey of Victoria covering the Eastern Otway Basin. 10 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

2 Exploration History 1962, sunk the first deep well in the onshore Eastern Otway, Anglesea-1A (Encl. 2). The well reached a total depth of 3067.8 mKB after penetrating 584.0 m of Tertiary sediments and 2484 m of Lower Cretaceous The Eastern onshore Otway Basin has had a long but sediments. It was designed as an off-structure chequered exploration history. Exploration for stratigraphic test in the southwest corner of PPL 256 hydrocarbons commenced in the early 1920s with SA where seismic indicated the sedimentary section above Oil Wells Company NL sinking two shallow wells, basement was thickest, and to see if there were any Anglesea-1 (140.8 m TD) and Anglesea-2 (229.5 m TD), porous beds within, or at the base of, the Otway near the coastal township of Anglesea. Both wells Group. The post-drill analysis, however, revealed bottomed in the Tertiary Eastern View Formation, but there were no Late Cretaceous sediments in the area, only minor hydrocarbons were encountered so they and it failed to encounter any porous beds within the were plugged and abandoned as dry holes. In 1923, Otway Group by the time it reached its initial target the Torquay Oil Wells Company sunk two wells depth of 2286 m. It was then decided to deepen the (Torquay-1 and –2) in the Parish of Jan Juk near well in an attempt to find porosity deeper within the Anglesea, followed by three more wells a year later Otway Group or at its base; but it was eventually (Torquay-3, -4 & -5). Torquay-1 bottomed in Lower plugged and abandoned in Eumeralla Formation at a Cretaceous Eumeralla Formation at 442.9 m and had depth of 3067.8 mKB when the rig could no longer drill weak gas shows in water from the Tertiary Eastern any further. No significant hydrocarbon shows were View Group between 221.3 to 221.9 m. The other four reported, but numerous gas kicks were detected wells, in contrast, did not encounter any hydrocarbons, between 1340 and 3064 mKB with gas levels varying with Torquay-2 and -5 bottoming in Lower Cretaceous from 5 to 40%. Eumeralla Formation (272.5 and 213.4 m respectively), and Torquay-3 and –4 bottoming in In 1963, Frome-Broken Hill Company Pty Ltd Eastern View Group (256.6 and 217.9 m respectively). acquired 214 km of seismic in the southwest corner of The same year Torquay-3, -4 and –5 were sunk, the PEP 6 around the township of Princetown (Princetown Point Addis Oil Company sunk a couple of shallow Seismic Survey); 2.3 km of which lie in VIC/O-01(1). wells called Torquay-6 and –7 in the Parish of Jan The objective of the survey was to map the pinchout Juk. The two wells bottomed in Eastern View Group point of Late Cretaceous sediments onto the western at a depth of 256.6 and 250.5 m respectively and both flank of the Otway Ranges for future exploratory reported weak oil (film and thick scum) and gas shows drilling. in the Eastern View Group. In 1965, Shell Development (Australia) Pty Ltd farmed In the late 1940s, the Geelong Flow Oil Company were in to PEP 5 and took over as operator from awarded a licence to explore an area north of the Frome-Broken Hill Company Pty Ltd, and Alliance Oil township of Torquay (PPL 141) on the southern side of Development Australia NL surrendered PPL 256. the Bellarine Peninsula. In 1948, the Geelong Flow In 1969, the area previously covered by PPL 256 was Oil Company drilled Geelong Oil Flow-1 approximately reissued as PEP 68 to Mr Leon Say. In 1970, PEP 68 4 km NNE of the coastal township of Torquay. The was transferred to Pursuit Oil NL who drilled well reached a total depth of 625.8 m after penetrating Hindhaugh Creek-1 (Encl. 3) later that year 365 m of Tertiary sediments and volcanics and 260.8 m approximately 14 km north of Anglesea-1A. The well of Lower Cretaceous sediments. Again, no information reached a total depth of 2371.7 mKB after penetrating is available on why Torquay was chosen as the site for 115.8 m of Tertiary sediments and 2255.9 m of Lower this well, and no geophysical logs were run. No Cretaceous sediments. It was designed to test whether significant hydrocarbon shows were reported either the Pretty Hill Formation was present in this part of except for a small quantity of inflammable gas (63.1% the Otway Basin and to gain better velocity data for hydrogen, 19.8% methane, 13.5% nitrogen, 1.4% future seismic work. The well was located on a carbon monoxide, 0.7% carbon dioxide, 0.5% oxygen) positive gravity anomaly that coincided with a soil encountered within the Otway Group (Boutakoff, geochemical (C1-C3) anomaly. Geophysical modelling 1949). suggested the Pretty Hill Formation was about 600 m In 1956, Frome-Broken Hill Company Pty Ltd were thick over the anomaly and was overlain by 600 m of awarded a license to explore all of the onshore Otway Eumeralla Formation and 120 m of Tertiary Basin west of the Bellarine Peninsula as far as the sediments. However, this interpretation proved townships of Port Campbell and Terang. The permit, incorrect, with the well still in Eumeralla Formation PEP 6, covered an area of 11,220 km2, but did not at TD, more than 1600 m below the predicted top of include 380 km2 of land between Anglesea and Barwon the Pretty Hill Formation. The well was eventually Heads which was awarded to Western Oil Ltd in 1959 plugged and abandoned with only minor fluorescence as PPL 256. encountered in the Eumeralla Formation. Other reported hydrocarbon indications include ignitable gas In 1960, PPL 256 was transferred to Alliance Oil between 709.5 to 723.0 m and oil scum between Development Australia NL with Western Oil Ltd 1263.0 to 1272.0 m. retaining a 20% interest. Later that year, Alliance Oil Development Australia NL acquired 50 km of seismic In 1971, Shell Australia acquired 421.7 km of seismic over the permit (Torquay Seismic Survey), and in (Warrnambool – Pomborneit Seismic Survey) in PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 11

PEP 6, and the block adjacent to it, PEP 5. The Cretaceous reverse fault features previously observed objective of the survey was to identify potential in the Colac survey. drillable structures onshore between Warrnambool In 1986, Hartogen Energy Limited acquired a further and Port Campbell. 209 km of seismic (Tomahawk Creek & 1986 In 1972, Shell Australia acquired 265.5 km of Experimental seismic surveys) in the Colac Trough. reconnaissance seismic (Colac – Geelong Seismic The objective of the Tomahawk Creek Seismic Survey Survey) in the Colac Trough with the objective of was to provide more coverage over the Tertiary and locating leads at the Pretty Hill Sandstone level. At Early Cretaceous reverse fault features observed in the same time, Pursuit Oil NL acquired 54 km of the earlier Colac and Stoneyford seismic surveys. The seismic (10 lines; Paraparap Seismic Survey) in objective of the 1986 Experimental Seismic Survey PEP 68. In 1974, Pursuit Oil NL surrendered PEP 68, (2 lines) was to determine whether or not an airgun with Shell Australia surrendering PEP 6 a year later. source would improve penetration and continuity of events within the Early Cretaceous Otway Group In 1980, Gas & Fuel Exploration NL were awarded a (Hunt, 1986). permit (PEP 100) to explore the entire onshore area between Point Reginald and Barwon Heads as far In 1987, Hartogen Energy Limited drilled a third well, north as Geelong and Lake Corangamite. The block Tirrengowa-1 (Encl. 6), 4 km to the SE of Stoneyford-1. covered an area of 5700 km2 and included land The well was designed to test a small fault-dependent previously issued as PPL 256, PEP 5 and PEP 68. closure on the upthrown side of a major NE-SW striking normal fault and reached a total depth of In 1982, Gas & Fuel Exploration NL drilled 1272.5 mKB after penetrating 342.0 m of Tertiary Olangolah-1 (Encl. 4) located in the middle of the sediments and volcanics and 903.0 m of Lower Otway Ranges at an elevation of 447.5 m above Cretaceous sediments before bottoming in Palaeozoic sea-level, approximately 9 km NNW of the township of basement. The primary target was the Pretty Hill Apollo Bay. The well was designed to test the Sandstone with porous sands in the overlying existence of Pretty Hill Formation in that part of the Eumeralla and Pebble Point formations listed as Eastern Otway Basin. It was located on a large secondary objectives. Reported hydrocarbon anticlinal structure defined by surface mapping and indications during drilling included up to 50% dull spudded in Eumeralla Formation. The well was yellow-gold fluorescence in the Pretty Hill Sandstone plagued by numerous wash-outs and severe hole with a weak yellow-white cut. No other hydrocarbons deviations, the latter of which eventually caused the shows were encountered so the well was plugged and well to be abandoned in Eumeralla Formation at a abandoned as a dry hole. depth of 2302 m TD. No hydrocarbons were encountered and the well was plugged and abandoned In 1988, Hartogen Energy Limited acquired a further as a dry hole. 122 km of seismic (12 lines) in the Colac Trough (Nalangil Seismic Survey). The survey was designed In 1983, Gas & Fuel Exploration NL shifted their primarily to in-fill gaps in the pre-existing grid, but attention to the Colac Trough where they acquired 233 later that year, Hartogen Energy Limited pulled out of line kms of regional seismic (Colac Seismic Survey). the permit and Gas & Fuel Exploration NL took over The objective of the survey was to define several leads as operator. previously mapped by Shell Development (Australia) Pty Ltd (1975) in this part of the permit (Montagnat, In 1990, Gas & Fuel Exploration NL drilled two 1983). shallow wells in the central part of the Colac Trough: Nalangil-1 and Ingleby-1. Nalangil-1 (Encl. 7) was In 1984, Gas & Fuel Exploration NL drilled a second sited approximately 13 km west of the township of well, Stoneyford-1 (Encl. 5), approximately 23 km west Colac and reached a total depth of 363.0 mKB after of the township of Colac at the southwestern end of the penetrating 290.0 m of Tertiary sediments and minor Colac Trough. The well was designed to test the volcanics and 73.0 m of Lower Cretaceous sediments. Pretty Hill Formation on the crest of a seismically The well was designed to test a seismically-defined, defined, SE-dipping half-graben, with Eumeralla fault-independent Tertiary anticline with four-way dip Formation providing vertical and cross-fault sealing. closure flanked to the NW and SE by reverse faults. It reached a total depth of 1203.0 mKB after The pre-drill objectives were the Tertiary Pebble Point penetrating 425.0 m of Tertiary sediments and and Dilwyn formations, but no significant hydrocarbon volcanics and 762.0 m of Lower Cretaceous sediments shows were observed so the well was plugged and before bottoming in Palaeozoic basement. No abandoned as a dry hole. The post-drill analysis later hydrocarbons were encountered and the well was revealed neither unit were present at the well site, plugged and abandoned as a dry hole. Late that year, with the well intersecting their non-marine Torquay Hartogen Energy Limited took over as operator of Sub-basin equivalent instead, the Eastern View PEP 100 with Gas & Fuel Exploration NL remaining Formation. Ingleby-1 (Encl. 8) was sited the title-holder. approximately 6 km to the east of Nalangil-1 and In 1985, Hartogen Energy Limited acquired 218 km of reached a total depth of 331.2 mKB after penetrating seismic in the Colac Trough (Stoneyford Seismic 244.5 m of Tertiary sediments and volcanics and Survey). The objective of the survey was to provide 86.7 m of Lower Cretaceous sediments. This well was better coverage over the Tertiary and Early designed to test another seismically-defined, fault- 12 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

independent Tertiary anticline with four-way dip than gas related. Later that year, Gas & Fuel closure like the Nalangil Structure. Again, the pre- Exploration NL was renamed GFE Resources Limited. drill objectives were the Tertiary Pebble Point and In January 1995, PEP 100 was reissued to GFE Dilwyn formations, but no significant hydrocarbon Resources Ltd as PEP 133 and subdivided into four shows were observed and the well was plugged and smaller blocks called ‘a’, ‘b,’ ‘c’ and ‘d’. Several months abandoned as a dry hole. The post-drill analysis later, Capital Energy NL surrendered PEP 130. revealed neither unit were present at this well site, with the well intersecting their non-marine Torquay In 1996, Basin Oil NL (a Cultus Petroleum NL Sub-basin equivalent, the Eastern View Formation. subsidiary) acquired PEP 133 from GFE Resources Ltd No hydrocarbons were encountered and both wells and acquired 50 km of seismic in the centre of the were plugged and abandoned as dry holes. Colac Trough (Irrewarra Seismic Survey). The survey was designed to confirm the presence of a shallow Soon after Ingleby-1 was drilled, the Geological Survey base-Tertiary roll-over structure observed on two of Victoria drilled a 1527 m deep stratigraphic well Gellibrand survey lines and define possible closures at called Warracbarunah-2 (see Encl. 9) on the the deeper Pretty Hill level. In 1998, Basin Oil NL northwestern flank of the Colac Trough approximately sited a well on the structure, Irrewarra-1 (Encl. 10), 16 km north of Ingleby-1. Gas & Fuel Exploration NL, but no hydrocarbons were encountered at the base- the operator of PEP 100, was a joint participant. The Tertiary level and the well was plugged and well was designed to test the presence of a previously abandoned at 553.0 m TD as a dry hole. Later that unidentified NE-SW striking Early Cretaceous half- year, Boral Energy assumed ownership of PEP 133 graben (Gellibrand Trough) and bottomed in Pretty with the acquisition of various Otway assets from Hill Formation. Numerous hydrocarbon indications Cultus Petroleum NL. Boral Energy then changed its were recorded from the Eumeralla Formation (710 to name to Origin Energy Resources Ltd and 866 mKB) and Pretty Hill Formation (866 to relinquished PEP 133 in 2000 without any additional 1527.5 mKB TD); primarily cut and crush cut seismic work or drilling. fluorescence in dried cuttings. The well was plugged and abandoned and completed as a ground-water observation bore. In February 1991, Gas & Fuel Exploration NL acquired 55 km of seismic in the northeast corner of the Colac Trough (Lake Mureduke Seismic Survey). The survey had two objectives: 1) to better define a previously-mapped structure in the area, and 2) to investigate two gravity anomalies in the vicinity of Mt Gellibrand and Mt Pleasant (Kemmis, 1991). In January 1992, Gas & Fuel Exploration NL acquired 302 km of seismic across the Colac Trough, Barrabool Hills and Anglesea Depression (Barwon Seismic Survey). Most of the lines were located in largely unmapped parts of the permit in an attempt to identify new structures. In March 1992, the permit (PEP 100) was transferred to Gas & Fuel Exploration NL and AGL Petroleum Operations Pty Ltd. Eight months later, the permit was transferred to Gas & Fuel Exploration NL and TMOC Exploration Pty Ltd. In February 1993, Petroleum Ventures Ltd were awarded a permit to explore the Bellarine Peninsula east of PEP 100. In March 1994, the permit, PEP 130, was transferred to Quicksilver Resources NL with Capital Energy NL (a non-title holder) acting as operator. In the same month, Gas & Fuel Exploration NL acquired 111 kms of seismic across the Colac Trough (7 lines; Gellibrand Seismic Survey) to provide better seismic control over two poorly-defined leads previously mapped by Blackburn (1992), and Barrett (1996). An AVO study was also conducted on an amplitude anomaly observed on a line (OGF94A-11) in the Colac Trough. The study (Simon Petroleum Technology Australia Pty Ltd, 1995) concluded the anomaly was most likely due to an intrusion rather PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 13

3 Basin Development this part of the basin, and the formation of the Otway Ranges via inversion of pre-existing Early Cretaceous normal faults. West of the Moyston Fault Trend, The structural history of the Otway Basin is compressional features are rare and basin-fill is summarised in Figure 4. The Otway Basin has a two largely undeformed. stage rift history associated with the break-up of Australia and Antarctica and the formation of the Southern Ocean. The first rift event occurred during the Tithonian – Barremian and resulted in the formation of a series of half-grabens that were progressively filled with Casterton Formation and Crayfish Subgroup. In the early Aptian, the basin then underwent a period of regional sag during which the Eumeralla Formation was deposited. This event lasted up until the end of the Albian. The second rift event occurred during the Turonian – Maastrichtian after a period of tectonic quiescence and non-deposition spanning the Cenomanian. This rifting resulted in the formation of a new set of half-grabens as far east as the Moyston Fault Trend, which opened up the western end of the Otway Basin to the ocean in the Duntroon Basin and allowed the sea to flood in. While this was happening, the rest of the basin east of the N-S oriented Moyston Fault Trend was undergoing folding, uplift and erosion, with up to 3 km of Otway Group stripped off the Otway Range and up to 2 km removed from the adjacent basement highs. Most of the space created by the extension to the west was accommodated by displacement along the E-W trending Tartwaup-Mussel Fault Zone, with the Moyston Fault acting as a sinistral strike-slip fault which prevented the rift from extending eastwards into the Eastern Otway Basin and Bass Basin. At the end of the Maastrichtian, Australia and Antarctica began to separate, and the two continents started to slowly drift apart at a rate of 4.3 mm/yr (Cande & Mutter, 1982), with Tasmania still attached to the Australian mainland. This event created a break-up unconformity at the top of the Sherbrook Group (67 Ma) and marks the onset of passive margin subsidence in the basin and the formation of the Southern Ocean (Lavin, 1997). The period of slow spreading lasted from the latest Maastrichtian (67 Ma) till the middle Eocene (49 Ma), during which the Wangerrip Group was deposited. In the Eastern Otway Basin, this event was punctuated by several phases of gentle compressional folding (Geary & Reid, 1998). At the end of the middle Eocene (49 Ma), the spreading rate in the Southern Ocean suddenly increased to its current rate of 110 mm/yr (Cande & Mutter, 1982) causing the Otway margin to rapidly subside. Another major transgression soon ensued, which cut off the supply of clastic sediments to the Wangerrip Group. This created a starved margin culminating in the deposition of the carbonate-rich Nirranda and Heytesbury groups. During the Late Miocene - Pliocene (15 – 0 Ma), the Otway Basin has been under NW-SE oriented compression. This compression has caused significant folding, uplift and erosion of the sedimentary fill in 14 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

EPOCH AGE STRATIGRAPHIC TECTONIC UNITS HISTORY SEAWARD LANDWARD

PLEISTOCENE Calabrian Newer Volcanics PLIOCENE L Piacenzian E Zanclean COMPRESSION / INVERSION Messinian Hanson L - major NE - SW folding Tortonian Port Plain Sand 10 Campbell - sea-level changes -> channeling Lst - uplift Otway Ranges MIOCENE M Serravattian Langhian - downward propagating NW-SE Burdigalian Gellibrand Marl ? detachment normal faulting 20 E - reverse faulting Aquitanian Clifton L Chatian Fm

OLIGOCENE MINOR COMPRESSION 30 E Rupelian MINOR INVERSION Narrawaturk L Priabonian Marl Demons Bluff Bartonian Fm THERMAL SUBSIDENCE 40 Mepunga Eastern EOCENE M Fm View Fm Lutetian MINOR INVERSION 50 Dilwyn E Ypresian Fm

Thanetian Pember Eastern THERMAL SUBSIDENCE L Mudstone View Fm PALEOCENE Selandian 60 Pebble E Danian Point Fm Cret / Tert Boundary Shale Member CONTINENTAL SEPARATION Maastrichtian - uplift / erosion 70 Timboon Sst

Paaratte Campanian Formation RIFTING: NE-SW EXTENSION 80 LATE Belfast - E-W to NW-SE faulting Nullawarre - down to S normal faulting Santonian Greensand Mudstone - transpressional folding Coniacian Flaxman Fm - reduction in heat flow 90 Turonian COMPRESSION / INVERSION Cenomanian Waarre Formation - differential uplift / erosion - uplift of Otway Ranges / Stawell Block 100 - high heat flow Albian Eumeralla Formation RIFTING / SAG - rift to thermal subsidence 110 Aptian MINOR STRUCTURING Katnook EARLY Barremian Sst 120 Laira Fm RIFTING: N-S EXTENSION Hauterivian Pretty Hill - E-W to NW-SE faulting 130 Formation - dominantly down to N normal faulting Valanginian

MINOR STRUCTURING Berriasian 140 Casterton Tithonian Formation RIFTING: N-S EXTENSION Kimmeridgian - E-W to NW-SE faulting 150 LATE

Oxfordian RIFT INCEPTION

160 MIDDLE Callovian LEGEND

Normal 300 Reverse

500 Transtensional

Compressional

INTENSITY

Figure 4 Tectonic history of the Otway Basin (from Geary & Reid, 1998). PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 15

4 Structural Elements who have modelled apatite fission track and vitrinite reflectance data from wells and outcrop in the Eastern Otway, virtually all of the basin east of the Moyston The Eastern Otway Basin is a structurally complex Fault Trend was affected by this event except for the region consisting of a Late Jurassic - Early Cretaceous southeastern part of VIC/O-01(1) and possibly the rift system overprinted by a Mid-Cretaceous inversion eastern half of VIC/O-01(3). Two NE-trending zones of event followed by a period of Tertiary subsidence and uplift and erosion approximately 100 km long and deposition which ended in the Late Miocene – Pliocene 40 km wide were identified: one centred on the present with localised uplift, folding and erosion. Because of day Otway Ranges (here called the ‘Otway Uplift’) its history, a large number of structural elements have and the other centred along the northwestern half of been recognised by previous workers and operators. VIC/O-01(1) between Stoneyford-1 and These structures can be broadly divided into four Warracbarunah-2 (here called the ‘Warracbarunah groups based on age: Late Jurassic – Early Cretaceous Uplift’). Most of the uplift and erosion appears to (Tithonian – Barremian), Mid-Cretaceous, uppermost have been centred on the present day Otway Ranges Late Cretaceous – Tertiary and Late Tertiary (Mid- where up to 3500 m of Eumeralla Formation is Miocene – Pliocene). A regional cross-section through estimated to be missing from the crest of the ranges in the Eastern Otway Basin is illustrated in Figure 5. Olangolah-1; approximately twice that estimated to be missing (1000 to 1500 m) from the Stoneyford-1 – Warracbarunah-2 area. 4.1 Late Jurassic - Early Cretaceous (Tithonian - 4.3 Upper Late Cretaceous - Barremian) Tertiary Structural elements of Late Jurassic - Early Structural elements of upper Late Cretaceous – Cretaceous age are shown in Figure 6. Four structural Tertiary age are illustrated in Figure 8. Five elements are recognised: the Gellibrand and depocentres are recognised: the Colac Trough, Barwon Ombersely troughs, and the Armytage and Stoneyford Downs Graben, Torquay Sub-basin, Anglesea highs. Embayment and Sorrento Graben. These elements The Gellibrand Trough and Ombersely Trough are were once part of a larger depocentre which covered half-grabens that formed during the first rift event. the entire Eastern Otway Basin both onshore and The Gellibrand Trough is the larger of the two and offshore up until the Mid-Miocene when a period of underlies the southeastern half of VIC/O-01(1). It is compression resulted in the formation of the Otway an ENE-WSW striking structure approximately 50 km Ranges, Barongarook High, Barrabool Hills and long and 30 km wide which deepens towards the SSE. Bellarine High (see next section). The Ombersely Trough is situated to the NW of the The Colac Trough is a NE-trending depocentre Gellibrand Trough. It is about 30 km long and 10 km located onshore to the northwest of the Otway Ranges. wide, and deepens towards the SSE as well. This It is approximately 80 km long and 40 km wide and trough was originally called the Gellibrand Trough by contains up to 600 m of sediment and volcanics (Abele Tabassi & Menhennitt (1991) who first identified it, et al., 1988; Edwards et al., 1996). In the past, the but in this report it is renamed after the township of term Colac Trough has been used by some workers in a Ombersely because the township of Gellibrand is structural sense to describe the main Late Jurassic – located over 40 km to the southwest of it above the Early Cretaceous half-graben in the area (here called Gellibrand Trough. the Gellibrand Trough) while others have used it in a The Armytage and Stoneyford highs are shallow geographic sense when referring to the overlying basement highs. The Armytage High is the up-dip upper Late Cretaceous – Tertiary fill (e.g. Geological continuation of the Gellibrand Trough and is the Survey of Victoria, 1995). In this report, the term footwall high to the adjacent Ombersely Trough. It is Colac Trough is used to define the extent of the upper located about 8 km south of Warracbarunah-2 and is Late Cretaceous – Tertiary fill only and not the situated at the junction of two major, down-to-the- underlying Late Jurassic – Early Cretaceous half- north faults, one striking NE-SW and the other grabens. striking E-W. The Stoneyford High is located about Internally, the Colac Trough can be divided into two 35 km WSW of the Armytage High in the southwest structural domains by the Colac Monocline. corner of VIC/O-01(1). Northwest of the Colac Monocline, the upper Late Cretaceous – Tertiary fill is relatively undeformed and the surface topography is relatively flat. Southeast of 4.2 Mid-Cretaceous the Colac Monocline, the upper Late Cretaceous – Tertiary fill is folded and faulted and the topography is At the end of the Early Cretaceous (~95 Ma), the correspondingly rugged. Numerous NE-trending folds Eastern Otway Basin was affected by a period of and faults have been mapped in this area including significant uplift and erosion. The areal extent and the Simpson Anticline, Pirrion Yallock Monocline, magnitude of this uplift is illustrated in Figure 7. Birregurra Monocline, Ferguson Hill Anticline, According to Cooper & Hill (1997), and Duddy (2000), 16 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

Coradjil Syncline, Princetown Syncline, Barwon Group to be uplifted and exposed. The areal extent Downs Graben, Barwon Downs Syncline, Barwon and magnitude of this event is illustrated in Figure 9. Monocline and Bambra Fault. These features are The Otway Ranges is the largest of the five and is shown on the 1:100 000 scale ‘Port Campbell approximately 80 km long and 40 km wide. It is Embayment’ and 1:50 000 ‘Colac and part of Beech composed almost entirely of Otway Group with a thin Forest’ map sheets and are described in more detail in veneer of Tertiary sediments draping its northwestern Geological Survey of Victoria (1995), and Edwards flank and northeastern end, and isolated pockets et al. (1996). preserved in several places along its southern and The Barwon Downs Graben is a narrow, NE- southeastern coast line (Edwards, 1962; Abele, 1979; trending fault-bounded graben located between the Tickell et al., 1991; Geological Survey of Victoria, Barongarook High and Otway Ranges (Tickell et al., 1995). The structure of the Otway Ranges has been 1991). It is approximately 20 km long and 5 km wide investigated by a number of workers (eg. Edwards, and deepens towards the NE where it opens out into 1962; Singleton, 1967; Medwell, 1971; Geological the Colac Trough. The Tertiary beds in the graben Survey of Victoria, 1995; Cooper, 1995a; Edwards have been down-faulted about 500 m relative to those et al., 1996) who have mapped numerous NE-trending on the adjacent blocks and have been folded into a faults and folds both along the coast and inland. broad asymmetric syncline (Barwon Downs Syncline) Major structures include the Crowes and Boonah with a steep northwestern limb. anticlines, the Johanna Syncline, the Castle Cove and Johanna faults, and Skenes Creek Monocline The Anglesea Embayment is the onshore extension (Singleton, 1967; Medwell, 1971). The location of these of the offshore Torquay Sub-basin to the east of the structures are shown on the 1:250 000 scale ‘Colac’, Otway Ranges. It covers the onshore area between 1:100 000 scale ‘Port Campbell Embayment’, and Anglesea and Barwon Heads and extends as far north 1:50 000 ‘Colac and part of Beech Forest’ map sheets. as the Barrabool Hills. The amount of section stripped off the Otway Ranges The Torquay Sub-basin contains up to 1500 m of during the Late Miocene – Pliocene is uncertain. sediments and volcanics, decreasing to less than 600 m Apatite fission track and vitrinite reflectance data in the Anglesea Embayment (Abele, 1979; Abele et al., suggest up to 1200 m of section was stripped of the 1988). The structure of the Anglesea Embayment is crest of the Otway Ranges and about 800 to 1000 m on summarised in Abele (1979), Abele et al. (1988), and the flanks (Cooper & Hill, 1997). This is supported by Holdgate et al. (2001). The dominant structures are the presence of Eastern View sediments the east-plunging Bald Hills Anticline and Bells Beach unconformably overlying Otway Group 400 m above Syncline. The Bald Hills Anticline is located about sea-level on the eastern flank of the Otway Ranges 10 km to the north of the township of Anglesea and about 6 km NW of the coastal township of Lorne crosses the coastline between Point Addis and Jarosite (Edwards, 1962). Headland. The Bells Beach Syncline is situated about 8 km to the north and crosses the coast near Bells The Barongarook High is located to the NW of the Beach. Two other folds have also been mapped Otway Ranges in the southeastern corner of the Colac onshore: a small south-plunging syncline immediately Trough. The structure is oriented NE-SW and is east of the township of Anglesea (Anglesea Syncline), bounded by monoclines to the southeast [Barwon, and a small E-W striking anticline (unnamed) to the Love] and northwest [Colac]. Mapping (Tickell et al., north of the Bells Beach Syncline. 1991) indicates the Barongarook High consists of a series of fault blocks over which the Tertiary beds are The Sorrento Graben is an extension of the Torquay draped forming broad, asymmetric anticlines. The Sub-basin. It is situated to the east of the Bellarine Otway Group is exposed in the cores of the fault blocks High and encompasses the southern part of Port which decrease in elevation to the northeast. Phillip Bay, the eastern tip of the Bellarine Peninsula, and most of the Nepean Peninsula. It contains up to The Barrabool Hills is a small ENE-WSW oriented 1200 m of Late Cretaceous – Tertiary sediments and is structure approximately 15 km long and 10 km wide bounded to the west by the Bellarine Fault and to the situated approximately 20 km to the NE of the Otway east by the NNE-trending Selwyn Fault. Its northern Ranges adjacent to the northern margin of the basin. boundary is probably faulted. It is bounded to the north by two ENE-WSW striking, down-to-the-south, reverse faults called the Barrabool and Newtown faults, and is asymmetric in cross- 4.4 Late Tertiary (Late Miocene - section with a steep north face. The structure of the Barrabool Hills is summarised in Coulson (1960), and Pliocene) Abele (1968). For the most part, the Otway Group is The Otway Ranges, Barongarook High, Barrabool poorly exposed except along the northern margin of the Hills, Paraparap High and Bellarine High are Late structure where it is well exposed in cliffs cut by the Miocene – Pliocene inversion features that formed in Barwon River. response to a period of NW-SE compression which The Paraparap High is a buried saddle which resulted in the reactivation of pre-existing Late connects the Colac Trough and Anglesea Embayment Jurassic – Early Cretaceous faults causing the Otway (Abele, 1979; Holdgate et al., 2001). It is situated between the Otway Ranges and Barrabool Hills and is PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 17

about 20 km long and 10 km wide. Bore data indicates the Otway Group on this structure occurs at a depth of about 200 m. The Bellarine High is located on the northern side of the Bellarine Peninsula about 20 km east of the Barrabool Hills. It is similar in size and orientation to the Barrabool Hills, but the Otway Group is not as well exposed and it is largely covered by a thin (< 30 m blanket) of Tertiary sediments and volcanics. It is bounded to the NNW by the Curlewis Monocline and to the SSE by the Bellarine Fault 18 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

A’

SSE

HIGH

KING ISLAND

SNAIL

TERRACE

sea level datum

TORQUAY SUB-BASIN

VIC/O-01(2)

OTWAY RANGES

ertiary

aceous - T

pper Late Cret

basement

VIC/O-01(1)

COLAC SUB-BASIN

Crayfish Subgroup

Eumeralla Formation

Pre-Mesozoic

Undifferentiated u

NNW

5 Regional cross-section across the Eastern Otway Basin (modified from Messent et al., 1999).

20 10

15 5

(km) Figure Figure

Depth PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 19 of

39° S

38° 30' S

38° S

39° S

38° 30' S

38° S

TWT (ms)

DEPTH TO

BASEMENT

500

1000

1500

2000

2500

3000

144° 30

144° E

TROUGH

AGE

HIGH

ARMYT OMBERSELY

143° 30

143° 30 ELBADTROUGH GELLIBRAND

HIGH arremian)structural elements in VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3). Colour-fill grid is a TWT structure map B

STONEYFORD

143° E

5 nt.

0 Late Jurassic – Early Cretaceous (Tithonian – 6

39° S

39° S op Baseme Figure Figure T

38° 30' S

38° 30' S 20 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

39° S

38° 30' S

38° S

39° S

38° 30' S

38° S

'E 144° 30 500

144° 30

ANGLESEA-1A

NERITA-1

SNAIL-1

3500

HINDHAUGH CREEK-1 1000

WILD DOG-1

144° E

144° E 1500

144° E

2500

3000

500 2000

1000

TA UPLIFT OTWAY 3500

WARRACBARUNAH-2

OLANGOLAH-1

odified from Cooper & Hill, 1997). Contour values in metres.

'E UPLIFT

KRAMBUCK-13

143° 30

143° 30 3000 1500

143° 30

143° 30 WARRACBARUNAH

A-1

STONEYFORD-1

TIRRENGOW

ROSS CREEK-1

PURRUMBETE-1

FERGUSON HILL-1

143° E

ERIC THE RED-1

143° E

PORT CAMPBELL-4

MINERVA-2

MINERVA-1

MUSSEL-1

GARVOC-1

FLAXMANS-1

PECTEN-1A

0 Mid-Cretaceous denudation map for the Eastern Otway Basin (m 7

39° S

39° S Figure Figure

38° 30' S

38° 30' S PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 21

39° S

38° 30' S

38° S

39° S

38° 30' S

38° S

GRABEN

SORRENTO FAULT

VOIR)

PAYWIT

BEH

MONOCLINE 'E PORTARLINGTON

TERTIARY DEPOCENTRE

144° 30

OUTCROP

TE MIOCENE - PLIOCENE INVERSION

WAARRE FM RESER

144° 30

ACEOUS -

ene – Pliocene faults, monoclines,

YMENT FAULT

Y SUB-BASIN NEWTOWN

GAS FIELD ( OTWAY GROUP

ZONE OF LA LATE CRET

SYNCLINE

ANTICLINE

EMBA ANGLESEA

BEACH FAULT

BBH

HILLS BARRABOOL

TORQUA

BELLS

BALD

FAULT

144° E

WURDIBOLUC ANTICLINE

144° E

FAULT

ANTICLINE

BOONAH

TDEFIANCE MT

BAMBRA SYNCLINE

MONOCLINE MONOCLINE

DOWNS

CREEK

MONOCLINE

SKENES

MONOCLINE

BARWON

BARWON CREEK

MONOCLINE ANTICLINE

COLAC TROUGH

ANTICLINE

COVE LOVE

BRH

SYNCLINE COLAC

143° 30

MONOCLINE

YALLOCK

MONOCLINE SYNCLINE

143° 30

ing the main Late Cretaceous – Tertiary depocentres and key Late Mioc

CASTLE

HILL JOHANNA

CROWES

PIRRION

JOHANNA

SYNCLINE

FAULT

VALE

FERGUSON

ANTICLINE PRINCETOWN CORADJIL

FAULT

PURRUMBETE

CHAPPLE SIMPSON

PORT

143° E

CAMPBELL

EMBAYMENT

20 s.

5 Surface structure map of the Eastern Otway Basin show

0 8

39° S

39° S nticlines and syncline Figure Figure a

38° 30' S

38° 30' S 22 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

39° S

38° 30' S

38° S

39° S

38° 30' S

38° S .

'E metres

144° 30

400 144° 30

144° 30

600 800

ANGLESEA-1A

NERITA-1

SNAIL-1

HINDHAUGH CREEK-1 1000

WILD DOG-1

144° E

1200

1000

WARRACBARUNAH-2 800

600 y Basin (modified from Cooper & Hill, 1997). Contour values in 400 OLANGOLAH-1

'E 200 'E

KRAMBUCK-13

143° 30

A-1

STONEYFORD-1

TIRRENGOW

ROSS CREEK-1

PURRUMBETE-1

FERGUSON HILL-1

143° E

ERIC THE RED-1

143° E

PORT CAMPBELL-4

MINERVA-2

MINERVA-1

200

MUSSEL-1

GARVOC-1 400

FLAXMANS-1

600 5

PECTEN-1A Late Miocene - Pliocene denudation map for the Eastern Otwa

0 9

39° S

39° S Figure Figure

38° 30' S

38° 30' S PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 23

5 Stratigraphy Pretty Hill Formation (Felton, 1997a,b). The formation underlies the entire report area and is in excess of 2400 m thick in places. It is undifferentiated The Late Jurassic – Tertiary fill in the Otway Basin is except for a basin margin fanglomerate sequence divided into eight unconformity-bounded groups called called the Barwon River Member (new name) which Otway, Sherbrook, Wangerrip, Eastern View, outcrops on the northern side of the Barrabool Hills Nirranda, Demons Bluff, Heytesbury and Torquay. As just north of the northern margin of VIC/O-01(1). The can be seen in Figure 10, the stratigraphic Barwon River Member consists of 60 m (base not seen) nomenclature of the Upper Cretaceous – Tertiary to of non-marine breccia-conglomerate, conglomerate, the west of the Otway Ranges is different from that in grit, sandstone and siltstone overlain by Eumeralla the Torquay Sub-basin to the east. The three blocks Formation. It outcrops in a river bank in the core of a covered in this acreage release effectively straddle this small inversion anticline bounded to the north by the boundary, with the two areas connected via the Colac Newtown Fault. Four distinct lithologic horizons are Sub-basin. present: a basal 30 m thick clast-supported, pebble- cobble breccia-conglomerate (Unit A), a 17 m thick micaceous, brown siltstone with floating granite 5.1 Otway Group pebbles (Unit B), a 5 m thick clast-supported pebble conglomerate (Unit C), and an 8 m thick sequence of The Late Jurassic – Early Cretaceous (Tithonian - interbedded pebble-conglomerate, grit and Albian) Otway Group is made up of three units (in volcaniclastic sandstone (Unit D) (see Fig. 11). Unit C ascending stratigraphic order): the Casterton contains Lower C. paradoxa spore-pollen and is middle Formation, Crayfish Subgroup and Eumeralla Albian in age. The presence of Cambrian greenstone Formation. less than 1 km along-strike to the west of the Barwon River Member (Coulson, 1960; Geological Survey of The Casterton Formation is a 26 to 535 m thick Victoria, 1963) suggests it probably occurs close to, or sequence of Tithonian - Berriasian (R. watherooensis - at, the base of the Eumeralla Formation at this lower C. australiensis spore-pollen Zone) non-marine locality. carbonaceous shale, siltstone, sandstone and minor basalt which unconformably overlie Palaeozoic basement (Parker, 1995; Ryan et al., 1995). The sediments accumulated in a lacustrine/swamp/ 5.2 Sherbrook Group floodplain environment (Lavin & Muscatello, 1997). The Sherbrook Group in the Otway Basin is divided The formation has been intersected in eleven wells in into six units (in ascending stratigraphic order): the the Victorian part of the Otway Basin, but it is Waarre Formation, Flaxman Formation, Belfast uncertain if it is present in the report area as it has Mudstone, Nullawarre Sandstone and Paaratte not been intersected by any petroleum wells or water Formation (Timboon Sandstone included). The bores to date. distribution of these units in the Eastern Otway is The Crayfish Subgroup is Early Cretaceous illustrated in Figure 12. Only one of these units (Valanginian - Barremian) in age and consists of three extends into the study area - the Timboon Sandstone. units: the Pretty Hill Formation, Laira Shale and The Timboon Sandstone is a sequence of fine- Katnook Sandstone. In the report area, only one of grained micaceous sand and minor coarse sand and these units is present, the Pretty Hill Formation. The gravel of Campanian – Maastrichtian (T. lilliei - other two units are restricted in their distribution to F. longus spore-pollen Zone) age which accumulated in the western half of the Otway Basin. a lower and possibly upper delta plain environment. In the report area, the Timboon Sandstone is The Pretty Hill Formation is a composite unit restricted in its distribution to the southwest part of consisting of a basal fine- to coarse-grained quartz the Colac Trough where it ranges from 30 to 60 m in sandstone [Pretty Hill Sandstone] overlain, in some thickness and unconformably overlies Eumeralla wells, by a package of interbedded carbonaceous Formation. Bore data indicates the Timboon shale/fine- to medium-grained quartz sandstone Sandstone extends, and thickens, into the adjacent [Pretty Hill Sandstone/Shale] (Parker, 1995). The Port Campbell Embayment where it gradationally formation unconformably overlies Palaeozoic basement overlies, and interfingers laterally with, deltaic and conformably overlies Casterton Formation where laminated siltstones and mudstones of the Paaratte penetrated (Parker, 1995; Ryan et al., 1995; Geological Formation which is Santonian to Maastrichtian Survey of Victoria, 1995). The sediments accumulated (T. apoxyexinus – F. longus spore-pollen Zone) in age. in a braided river environment and contain Valanginian - Barremian spore-pollen (Upper C. australiensis - F. wonthaggiensis Zones). The Eumeralla Formation is a sequence of non-marine fine- to medium–grained volcaniclastic sandstone, mudstone and coal of Aptian – Albian (P. notensis - P. pannosus spore-pollen Zone) age which unconformably overlies Palaeozoic basement and 24 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

SHOW

EASTERN VIEW GROUP

DEMONS TORQUA BLUFF GROUP GROUP

TORQUA

SUB-BASIN

SHOW

AND GAS SHOW

TED

(CO )

STRONG OIL

SHOW

BASIN

OTWAY UNDIFFERENTIA HEYTESBUR NIRRANDA WANGERRIP SHERBROOK OTWAY QUAT. - RECENT GROUP GROUP GROUP GROUP GROUP

GAS WELL

GAS SHOW (WEAK) WEAK OIL STRONG OIL STRONG OIL GAS WELL GAS WELL

TION

FORMA

BOONAH FORMA

SILTSTONE

JAN JUC FORMA

PUEBLA

ANGLESEA

ANGAHOOK FORMA

TORQUAY SUB-BASIN

GROUP

EASTERN VIEW

ANGLESEA

ONE

OTWAY

TION

RANGES

TION

SKULL CREEK MUDST

VICTORIA

TION

COLAC

TROUGH

NULLAWARRE GREENSAND

FLAXMAN FORMA

WAARRE FORMA

ONE

CLIFTON FORMA

TION

EMBAYMENT

PORT CAMBELL

FORMA

ONE

ON FORMA

BASEMENT

HILL SANDST

ONE

SANDT

HEATHFIELD

TION

MEPUNGA

EMBAYMENT

CASTERT

TYRENDARRA

PRETTY

ONE

HANSON PLAIN SAND / NEWER VOLCANICS

BELFAST MUDST

LIMEST

PAARATTE FORMA

TROUGH

TION

PORTLAND

TIMBOON SANDST

ARDONACHIE TROUGH

GELLIBRAND MARL

TION

ONE

FORMA

TION

PORT CAMPBELL

HIGH

EUMERALLA

DILWYN FORMA

TION

PEMBER MUDST

PEBBLE POINT FORMA

LAIRA

NARRAWATURK MARL

FORMA

KALANGADOO

PENOLA TROUGH

ONE

SOUTH

AUSTRALIA

SANDST

WINDERMERE

ONE

(CONDENSED )

TROUGH

ST CLAIR

KATNOOK

SHERBROOK GROUP

SANDT

NARRACOORTE LIMEST

GAMBIER LIMEST

ROBE

TROUGH

TIAN

APTIAN

ALBIAN

TURONIAN

CONIACIAN

TITHONIAN

SANTONIAN

CAMPANIAN

BERRIASIAN

BARREMIAN

MAASTRICH-

VALANGINAIN

HAUTERIVIAN

EOCENE

CENOMANIAN

MIOCENE

LATE PLIO-PLEIST LATE

PALEOCENE

OLIGOCENE EPOCH / AGE EARLY

ZOIC

TERTIARY

CRETACEOUS Stratigraphy of the Otway Basin. Area covered in this report highlighted in red. PALAEO-

ERA /

PERIOD

JURASSIC

10 20 30 40 50 60 70 80 90

110

100 120 130 140

(Ma)

AGE Figure 10 Figure PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 25

BASIN MARGIN FOOTWALL HIGH [SHALLOW BASEMENT WITH THIN TERTIARY COVER]

BARWON TYPE SECTION OF BARWON RIVER MEMBER (SEE PHOTOMOSAIC BELOW)

37 5 8 55 30 10 7 8 NEWTOWN FAULT 40 20 15 10 BARRABOOL18 FAULT10 10 8 10 10 5 10 20 25 2 10 10 30 10 15 10 12 10 10 10 10 8 10 10 17 12 10 5 5

5 5 RIVER 6 5 BARRABOOL 2 10 HILLS 12 5 15

UNDIFFERENTIATED EUMERALLA FORMATION BARWON RIVER MEMBER

DEVONIAN GRANITE

CAMBRIAN GREENSTONE 5KM

NORTH SOUTH

NEWTOWN ANTICLINE

NEWTOWN FAULT

FYANSFORD CLAY (OLIGOCENE - MIOCENE)

UNDIFFERENTIATED 50 CM UNIT D EUMERALLA UNIT D BARWON FORMATION RIVER UNIT B MEMBER

UNIT A UNIT A

Figure 11 Simplified geological map of the Barrabool Hills showing the outcrop extent of the Barwon Hills Member and Eumeralla Formation. Photomosaic interpretation below map is a view of the type section from the north side of the Barwon River.

26 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

GRP SHERBROOK

EDGE

PAARATTE FM NULLAWARRE GSD SKULL CREEK MST

BELFAST MST FLAXMANS FM WAARRE FM SUBCROP OTWAY GROUP

OUTCROPPING EUMERALLA

38° S

39° S

VIC/O-01(3)

144° E

VIC/O-01(1)

VIC/O-01(2)

143° E

Distribution of Sherbrook Group units and Late Cretaceous Eastern View Group in VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3).

38° S

39° S

Figure Figure PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 27

5.3 Wangerrip Group/Eastern View Moomowroong Sand probably grades laterally into, and locally disconformably overlies, the Wiridjil Group Gravel. Such a disconformable contact is exposed in a road cutting along Gellibrand River Road just south of Wangerrip Group its junction with Westwicks Road, and in a gravel pit beside Silks Road 3 km northwest of Carlisle River The Wangerrip Group in the Otway Basin consists of township. Where the Wiridjil Gravel is absent, the five units: the Pebble Point Formation, Wiridjil Gravel, Moomowroong Sand rests on the Timboon Sand Moomowroong Sand, Pember Mudstone and Dilwyn Member. The unit probably accumulated in a shallow Formation. The distribution of these units in the marine to marginal marine environments as it Eastern Otway is illustrated in Figure 13. contains sparse foraminifera. The Pebble Point Formation is a sequence of The Pember Mudstone is a silty claystone of Late marginal marine, carbonaceous sandy claystone, Palaeocene – Early Eocene age which conformably granule conglomerate and fine- to coarse-grained overlies the Pebble Point Formation and quartz sandstone of Late Maastrichtian – Palaeocene Moomowroong Sand at the southwestern end of the age which unconformably overlie Eumeralla Colac Trough. The unit is less than 50 m thick in the Formation and Timboon Sandstone at the report area, increasing to a maximum of 69 m in the southwestern end of the Colac Trough. The Port Campbell Embayment. The sediments sandstones are ferruginous in part, and contain accumulated in a low-energy marine environment. iron-rich oolites and pisolites as well as glauconite The Dilwyn Formation is a sequence of interbedded (Tabassi & Davey, 1986). The sediments contain carbonaceous silty clay, hard ferruginous coarse- Upper F. longus - Upper L. balmei Zone spore-pollen grained sandstone, carbonaceous sandy clay, and clean and M. druggii - E. crassitabulata Zone microplankton. fine- to medium-grained sand of Early Eocene age The Wiridjil Gravel is a sequence of unconsolidated which unconformably overlies the Eumeralla gravel, coarse sand and minor pebble beds of Formation and conformably overlies the Pember Palaeocene (L. balmei spore-pollen Zone) age which Mudstone at the southwestern end of the Colac overlie the Timboon Sand Member in the southwest Trough. It is less than 100 m thick in the report area, corner of the Colac Trough in the Parishes of Wiridjil thickening to over 200 m in the Port Campbell and Moomowroong (Tickell et al., 1992). The unit crops Embayment. The sediments were deposited in a out in a series of road cuts along the Gellibrand River shallow marine environment and display an overall Road between Westwicks Road and Sand Pit Road, shallowing of water depth with time, probably and also outcrops over a distance of about 15 km along reflecting a prograding deltaic sequence. The basal the Gellibrand River from the township of Carlisle beds accumulated in a shallow, nearshore, restricted River area southwest to Devondale. It attains 70 m in marine environment similar to that of the Pebble Point thickness in the Moomowroong 15001 bore and Formation. The upper part of the formation has much becomes finer-grained toward the north and east of the cleaner sand layers which are likely to represent town of Carlisle River. The contact between the shoreface deposits of a coastal barrier system, while Wiridjil Gravel and underlying Timboon Sand Member the interbedded clays may be back beach lagoonal is not known from outcrop but appears to be sediments. conformable as no unconformity has been recognised in bore sections. The unit probably accumulated in a high-energy fluviatile environment based on the Eastern View Group presence of cross-beds up to 2 m high and the absence of marine microfauna. Towards the west, the Wiridjil The Eastern View Group is a sequence of Gravel appears to grade laterally into, and is locally undifferentiated Palaeocene to Late Eocene (L. balmei disconformably overlain by, the Moomowroong Sand. – M. diversus spore-pollen Zones) non-marine sand and minor carbonaceous silt, clay and brown coal The Moomowroong Sand is an unconsolidated which unconformably overlie the Eumeralla Formation Palaeocene (L. balmei spore-pollen Zone) fine-grained in the Colac Trough, onshore Torquay Sub-basin and sand with minor clay bands. The unit is named after Sorrento Graben (see Fig. 13). It is the same age as the Parish of Moomowroong where the type locality is the Pebble Point Formation, Wiridjil Gravel and located - a road cutting along the Gellibrand River Moomowroong Sand, and interfingers with the latter Road (YC 014233) 1 km west-northwest of Mount at the southwestern end of the Colac Trough. The Mackenzie, and another cutting 100 m to the east. Eastern View Group accumulated in an upper to lower The formation is estimated to be about 45 m thick delta plain environment. The coarse sands at the top here; 35 m of which are exposed but not the base and of the unit are interpreted as high-energy braided the top. The interval between 74 and 129 m in the stream deposits while the underlying fine sand and silt Moomowroong-1 bore, 2 km to the west, is a good may be meandering stream or even coastal barrier reference section. The formation outcrops for about deposits. The basal beds, which are rich in coal and 15 km along the Gellibrand River southwest from carbonaceous clay, reflect swamp and freshwater lake Carlisle River. It has been traced basinward away environments. The unit is in excess of 450 m thick in from the Otway Ranges where it grades laterally into Anglesea-1A and probably exceeds 600 m in the the Pebble Point Formation. Inland, the

28 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

GRP WANGERRIP

EDGE

GRAVEL

EASTERN VIEW GRP PEMBER MST DILWYN FM WIRIDJIL MOOMOWROONG SAND PEBBLE POINT KT SHALE

SUBCROP OTWAY GROUP OUTCROPPING EUMERALLA

38° S 39° S

/O 01(3).

VIC/O-01(3)

144° E

VIC/O-01(1)

VIC/O-01(2)

Eastern View Group sediments in VIC/O-01(1), VIC/O-01(2) and VIC

143° E

Distribution of Wangerrip Group units and Early Tertiary

38° S

39° S

Figure Figure PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 29

deepest part of the Barwon Trough. In the Colac Mepunga Formation and Narrawaturk Marl at the Trough, it is up to 60 m thick. southwestern end of the Colac Trough. The sediments are interpreted to have accumulated in a restricted, shallow marine environment; the lower part largely in 5.4 Nirranda Group/Demons Bluff lagoons behind Mepunga Formation barrier islands Group (Blake, 1980). In the Torquay Sub-basin, the Demons Bluff Group is divided into three formations (from bottom to top): the Nirranda Group Boonah Formation, Anglesea Siltstone and Angahook Formation. The Boonah Formation is a sequence of The Nirranda Group in the report area consists of two Late Eocene (Middle N. asperus Zone) fluvial sand, units: the Mepunga Formation and Narrawaturk Marl. gravel, clay and coal up to 70 m thick. The Anglesea The Mepunga Formation is a sequence of Siltstone is a marginal marine carbonaceous silt up to unconsolidated sand and silt of Middle Eocene to Early 180 m in thickness which conformably overlies the Oligocene age, which disconformably overlie Dilwyn Boonah Formation in the Anglesea area and Formation. The unit is best known from the onshore unconformably overlies the Eumeralla Formation Port Campbell Embayment where it has been north of Hindhaugh Creek-1. The Angahook intersected in over 50 wells and bores. Four units are Formation is a sequence on interbedded nonmarine recognised there (from base to top): the Sturgess Point to shallow marine sand, gravel, basalt, tuff and Member, Lower Mepunga Sand, Brucknell Member, breccia. The formation is restricted in its outcrop- and Upper Mepunga Sand. The Sturgess Point subcrop extent to the Aireys Inlet area south of Member and Brucknell Member are dark brown, Anglesea where it is up to 37 m thick. carbonaceous clayey-silt to silty-clay units, and the Lower and Upper Mepunga sands are unconsolidated medium- to coarse-grained, iron-stained quartz sand 5.5 Heytesbury Group/Torquay units. Only two of these units are present in the report area: the Sturgess Point Member and Lower Group Mepunga Sand. The two units are restricted to the The Heytesbury and Torquay groups are Late western edge of VIC/O-01(1) where they grade Oligocene to Late Miocene in age and mark the first laterally northeastwards into Demons Bluff major development of shelf carbonates in the Otway Formation. The Sturgess Point Member in this area is Basin. interpreted as an estuarine unit and the lower Mepunga Sand a beach and nearshore barrier island deposit (Blake, 1980). The two units have a combined Heytesbury Group thickness of less than 50 m and contain Middle Eocene spore-pollen (Lower N. asperus Zone) and planktonic The Heytesbury Group in the report area consists of foraminifera (A. primitiva Zone). two units: the Clifton Formation and Gellibrand Marl. The Narrawaturk Marl is a pale to dark brown, The Clifton Formation is a sequence of shallow marine marl and calcareous mudstone which grades marine, fossiliferous, medium- to coarse-grained laterally into, and conformably overlies, the Mepunga calcarenite and marl which overlies the Narrawaturk Formation (Geological Survey of Victoria, 1995). In Marl and Demons Bluff Formation in the Colac the report area, the Narrawaturk Marl is restricted in Trough. The basal contact is conformable in the Colac its outcrop/subcrop extent to the southwestern half of Trough and disconformable along the northwestern the Colac Trough (VIC/O-01(1)) and to the Aire flank of the Otway Ranges. The formation outcrops District at the southwestern end of the Otway Ranges poorly but can be traced as a distinct feature on aerial between the mouth of the Johanna River and Castle photographs along the northwestern flank of the Cove (Geological Survey of Victoria, 1995). It is Late Otway Ranges and around the Ferguson Hill Eocene to Early Oligocene in age and is up to 100 m Anticline. Its distribution in these areas is patchy, but thick in the report area. subsurface to the northwest the unit forms a sheet-like deposit which extends over most of VIC/O-01(1). The formation is very late Early Oligocene to very early Demons Bluff Group Miocene in age and is generally less than 20 m thick in the report area, thinning to less than 1 m along the The Demons Bluff Group is a sequence of Middle western edge of the Otway Ranges. Eocene to early Late Oligocene dark brown, carbonaceous, silt, fine sand, clay and clayey-sand up The Gellibrand Marl is a sequence of Early to Middle to 360 m thick which conformably and disconformably Miocene shallow marine, fossiliferous, calcareous silty- overlies the Dilwyn and Eastern View formations in clay, clayey-silt and minor fine- to coarse-grained the Colac Trough and Torquay Sub-basin (Geological calcarenite beds up to 400 m thick which conformably Survey of Victoria, 1995). overlie Clifton Formation in the Colac Trough and disconformably overlie Dilwyn Formation along the In the Colac Trough, the Demons Bluff Group is northwestern flank of the Otway Ranges (Geological undifferentiated and interfingers laterally with the Survey of Victoria, 1995). The formation is well 30 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

exposed on the coast to the southwest of VIC/O-01(1) Basalt has been intersected in many wells and bores to and outcrops over a large area between Simpson, the north and east of Colac such as Struan-1, Princetown, Port Campbell and Timboon, and in the Struan-2, Warracbarunah-2, Cressy-1, Birregurra-1 Barwon Downs Graben. and Ingleby-1. The maximum recorded thickness is 141 m in Struan-1, while in Birregurra-1 only 9 m is present. In Struan-2, the basalt has been Torquay Group radiometrically dated as 59.1 ± 1.0 Ma (McKenzie et al., 1984). In Warracbarunah-2 and Birregurra-1, The Torquay Group is made up of two units: the Jan the basalt lies between Eumeralla and Eastern View Juc Formation and Puebla Formation. formations. The basalt in these wells is regarded as The Jan Juc Formation is Oligocene to Early Palaeocene in age as the overlying Eastern View Miocene in age consists of three formations: the Point Formation spans the L. balmei spore-pollen Zone. Addis Limestone, Jan Juc Marl and Waurn Ponds Oligocene basalts are also present in VIC/O-01(3) near Limestone. The Point Addis Limestone is a shallow Aireys Inlet at Split Point. K/Ar dating indicates the marine bioclastic limestone up to 23 m thick which basalt there is 26.5 to 27.0 Ma in age. Similar conformably to disconformably overlies the Angahook volcanics also crop out around Mt Bellarine on the Formation. It outcrops onshore on the coast at Aireys Bellarine Peninsula. Basalts have also been Inlet and thins towards the north, west and northeast. intersected in coal shafts near Mt Bellarine where it is The Jan Juc Marl is a deep-water fine-grained up to 22 m thick (Daintree, 1861). calcareous mudstone up to 88 m thick which conformably overlies the Angahook Formation and interfingers laterally with the Point Addis Limestone. 5.7 Newer Volcanics The formation outcrops on the coast near Torquay and thins up on to the Otway Ranges-Barrabool Hills saddle where its grades laterally into undifferentiated The basalt field which extends across the north of the Heytesbury Group. The Waurn Ponds Limestone is Eastern Otway Basin between Warrnambool and a 10 m thick sequence of bryozoan calcarenite and Pirrion Yallock represents the southern margin of the marl which outcrops – subcrops along the southern larger Western Districts Volcanic Plain. It is margin of the Barrabool Hills and grades laterally composed of undifferentiated plains basalt, stony rise southwards into the Jan Juc Marl. basalt, scoria and tuff. These are late Tertiary to The Puebla Formation is a clayey calcareous Pleistocene in age and are known as the Newer siltstone of Miocene age which disconformably overlies Volcanics. Many eruption points, in the form of maar the Jan Juc Formation. The formation is up to 30 m volcanoes and scoria cones, are present across the thick onshore, increasing to over 700 m offshore. plains. Basaltic lava flows form the bulk of the unit which ranges up to 50 m but on average is less than 30 m 5.6 Older Volcanics thick. On a regional scale, the volcanics thicken towards the north. Local variability in thickness is attributed to the irregular late Tertiary erosion Basalts and tuffs of early to mid-Tertiary age outcrop surface on which they rest. They disconformably and subcrop extensively throughout the report area. overlie Hanson Plain Sand, Port Campbell Limestone In the Gellibrand area, a basalt plug intrudes the and Gellibrand Marl. Eumeralla and Eastern View formations (Tickell et al., 1991) in the southwest corner of VIC/O-01(1). K/Ar The Plains Basalt, a monotonous sequence of dating (McKenzie et al., 1984) indicates the plug is widespread and overlapping lava flows, has yielded Late Oligocene in age. This is consistent with the radiometric ages of about 2 Ma. The maars, scoria presence of pillow basalt and pyroclastics in the upper cones and stony rise basalts are generally younger. part of the Demons Bluff Formation up to 10 km from Ages of 586,000 and 260,000 years have been obtained the plug. These have been interpreted as originating from the Stony Rise Basalts. Variation in the degree from the plug (Tickell et al., 1991) and have been of soil formation and in the amount of dissection of the radiometrically dated as 28.5 ± 0.6 Ma (McKenzie volcanic cones suggests that they formed over a wide et al., 1984). time range during the Pleistocene. At Mount Murray, just west of Gellibrand, a basalt sill intrudes the Eastern View Formation, while in Seaview-1, 10 km to the west of VIC/O-01(1), a basalt sill intrudes the Paaratte Formation. All these occurrences are of limited extent and are probably related to the same Late Oligocene volcanic event known as the ‘Yaugher Volcanics’ (Tickell et al., 1991). PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 31

6 Seismic Data available for 75 (60%) of the 124 lines in the block. MPV has all of this SEGY except line BMR92-OT1 which can be purchased from AGSO. 6.1 Seismic coverage VIC/O-01(2) is covered by a sparse seismic grid comprising 8 lines (4 surveys) totalling 50.3 line kms. The lines are widely spaced and consist primarily of lines that penetrate a short distance into the block The onshore Eastern Otway Basin is covered by a from the adjacent VIC/O-01(1) and VIC/O-01(3) blocks. relatively poor 2D seismic grid consisting of 1665.7 Only one line is located entirely within VIC/O-01(2), line kms of seismic (136 lines). Sixteen seismic OHG86D-202, at the southwest end of the Otway surveys have been acquired over the past forty years – Ranges. No SEGY is available for this line. the first in 1960 (Torquay Seismic Survey) and the last BMR92-OT1 is a regional AGSO line which traverses in 1996 (Irrewarra Seismic Survey). A summary of both VIC/O-01(1) and VIC/O-01(2). The remaining six these seismic surveys is provided in Table 1. The lines are line tails only. MPV has SEGY for four of distribution of seismic lines within VIC/O-01(1), these lines. VIC/O-01(2) and VIC/O-01(3) is illustrated in Enclosures 11 and 12. Enclosure 11 illustrates which VIC/O-01(3) is covered by a sparse seismic grid like lines are available in SEGY format. In Enclosure 12, VIC/O-01(2). The seismic coverage comprises 15 lines the sixteen seismic surveys are colour-coded for easy (3 surveys) totalling 173.4 line kms. The lines are all identification. located in the western half of the block and were acquired in 1960 (Torquay Seismic Survey), 1982 VIC/O-01(1) is covered by a moderately extensive (Colac Seismic Survey) and 1992 (Barwon Seismic seismic grid comprising 124 lines (14 surveys) totalling Survey). Only the Barwon Seismic Survey lines are 1442.0 line kms. The majority of lines are located in available in SEGY format from MPV. an ENE-WSW trending corridor about 20 km wide running through the middle of the block. SEGY is

Table 1: Seismic surveys in VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3)

Year Survey Name Kms* MPV Prefix Operator Contractor

1960 Torquay 51.7 ODNL60A Oil Development NL Geoseismic 1963 Princetown 2.3 OFBH63A Frome - Broken Hill Ray Geophysics 1971 Warrnambool- 15.4 OFBS71A Shell Geophysical Services Pomborneit International 1972 Colac-Geelong 277.8 OFBS72A Shell Geophysical Services International 1972 Paraparap 54.1 OLPO72A Pursuit Oil NL G.E.S. Pty Ltd 1983 Colac 230.7 OGF82A Gas & Fuel Exploration NL Petty-Ray Geophysical 1984 Terang 1.6 OPX84A Phoenix Oil & Gas Seiscom Delta 1985 Stoneyford 215.2 OHG85A Hartogen Geosystems 1986 Tomahawk Creek 184.9 OHG86A Hartogen Geophysical Services Ltd 1986 1986 Experimental 21.7 OHG86D Hartogen Norpac International 1988 Nalangil 122.9 OHG88A Hartogen Petty-Ray Geophysical 1991 Lake Mureduke 54.3 OGF91A Gas & Fuel Exploration NL Geosystems 1992 Barwon 298.2 OGF92A Gas & Fuel Exploration NL Western Geophysical 1992 BMR Otway Basin 60.2 BMR92OT BMR BMR 1994 Gellibrand 77.8 OGF94A GFE Resources Ltd GECO-PRAKLA 1996 Irrewarra 50.1 OC96B Cultus Geosystems

* = survey line length calculated only for lines within VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3) 32 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

6.2 Seismic Interpretation and 3) the absence of an angular unconformity between the Otway Group and overlying upper Late Mapping Cretaceous – Tertiary in the Barwon Downs Graben. Line C is located in western half of VIC/O-01(3) and TWT Structure Maps ties into Hindhaugh Creek-1. This line runs along the western side of the Barrabool Hills and extends Two horizon maps have been produced for this report: southwards into the Anglesea Embayment. The main a Top Basement map (Encl. 13) and a Top Eumeralla features to note on this line are: Formation map (Encl. 14). The top of the Pretty Hill Formation was not interpreted due to time constraints. 1) the gradual increase in thickness of the Crayfish Subgroup towards the Barrabool Fault; Top Basement 2) the inversion on the Barrabool Fault; Enclosure 13 highlights the Early Cretaceous half- 3) the lack of faulting in this part of the basin; and grabens. Two half-grabens are visible in VIC/O-01(1), the Gellibrand Trough and Ombersely Trough. The 4) the thickness of the Tertiary section in this part of half-grabens are oriented NNE-SSW and deepen the basin. toward the SSE. The Gellibrand Trough is larger of the two and appears to extend beneath the Otway Ranges. The Ombersely Trough is a much smaller half-graben located to the NW of the Gellibrand Trough. The two troughs are separated by the Armytage High.

Top Eumeralla Formation Enclosure 14 illustrates the structure of the Colac Trough. The Barongarook High shows up as a large block of uplifted Eumeralla Formation in the centre of the Colac Trough.

Interpreted Seismic Sections Enclosure 15 contains three seismic sections which highlight the main structural features of VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3). The lines are called (from west to east) A, B and C. Line A is located near the southwestern end of VIC/O-01(1) and ties into Stoneyford-1 and Tirrengowa-1. This line illustrates the relationship between the Stoneyford High and Gellibrand Trough. The main features to note are: 1) the rapid thickening of the Otway Group into the Gellibrand Trough; 2) the angular unconformity at the top of the Otway Group; and 3) the uniform thickness of the upper Late Cretaceous – Tertiary section in the Colac Trough (except in areas affected by Late Miocene – Pliocene deformation). Line B is located at the northeastern end of VIC/O-01(1) and ties into Warracbarunah-2. This line illustrates the relationship between the Ombersely Trough, Armytage High and Gellibrand Trough. The main features to note on this line are: 1) the size of the Ombersely Trough with respect to the Gellibrand Trough; 2) the Late Miocene – Pliocene deformation associated with the Barongarook High; and PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 33

7 Other Geophysical Data western edge of VIC/O-01(1). This feature corresponds to the shallow (< 1.5 km deep) basement high (Stoneyford High) visible beneath Stoneyford-1 and Tirrengowa-1 in Enclosures 13 and 16 (Line C). The 7.1 Gravity Barongarook Gravity High (Geological Survey of Victoria, 1995) is a small, NE-trending, arrowhead shaped gravity high which underlies the present-day Enclosure 16 is a bouguer gravity image of the Eastern Barongarook High. Seismic observations suggest the Otway Basin. The onshore part of the basin is covered positive gravity anomaly associated with this structure by a semi-regional gravity grid with an average station is also a response to shallow basement. spacing of 1.5 km. The grid is based on gravity data The Moolap Gravity Low (new name) is the acquired by petroleum exploration companies, AGSO, prominent N-trending gravity low located between the GSV and Melbourne University, and is available from Barrabool Hills and Bellarine Peninsula in GSV in digital format (see ‘MPV Contacts’ section at Enclosure 16. The low appears to extend southwards the back of this report for contact details). The into the Anglesea Embayment and Torquay Sub-basin offshore gravity is a grid of Bouguer gravity anomalies which may indicate the presence of a thick Late corrected for bathymetric differences. This grid is Jurassic - Tertiary section in this area. Alternatively, based on ship-borne gravity measurements acquired the low could reflect the presence of granite at shallow by petroleum exploration companies and AGSO, which depth, as large areas of granite crop out just to the Des Fitzgerald & Associates recently levelled on behalf north of the Barrabool Hills and Geelong. of MPV. The offshore gravity grid is not currently available to the public. A good summary of the history of gravity exploration 7.2 Magnetics in the Eastern Otway Basin can be found in Geological Survey of Victoria (1995, p.43-45) who interpreted a large part of the area covered in this report and have Enclosure 17 is a regional total magnetic intensity named and describe some of the gravity anomalies, (TMI) image of the Eastern Otway Basin. The Eastern many of which are coincident with structural elements Otway basin is covered by three airborne surveys, one previously defined in Section 4. Three features stand onshore [Colac] and two offshore (Bass Strait – out in particular in this image: the Otway Ranges Encounter Bay & Otway Basin). The three surveys Gravity High, the Colac Gravity Low and Moolap have been stitched together by GSV to produce a single Gravity Low. grid which is available from the GSV in digital format The Otway Ranges Gravity High (Geological Survey on request. The Colac Survey was acquired in 1999 by of Victoria, 1995) is a prominent NE-plunging gravity GSV and has a 200 m line spacing. The Bass Strait – high coincident with the Otway Ranges - Paraparap Encounter Bay Survey (6500 m line spacing) was High. Originally, the unusually high gravity response acquired by Haematite Exploration in 1961 and covers associated with these structures was thought to reflect the Torquay Sub-basin and King Island High. The shallow basement, but it is now widely accepted that it Otway Basin Survey (500 m line spacing) was acquired is due to the density of the Otway Group and not depth by AGSO in 1994 (Gunn et al., 1995) and covers all of to basement. In Hindhaugh Creek-1 on the Paraparap the offshore Otway Basin west of the King Island High High, the Otway Group has exceptionally high as far out as the 1000 m isobath. 3 densities (range: 2.6 to 2.7 T/m ) suggesting it too has Several features stand out on the TMI image. The been deeply buried and then uplifted (Geological most obvious are: Survey of Victoria, 1995). This interpretation is supported by burial history studies (Cooper & Hill, 1) the high frequency noise over the northern half of 1997; Duddy, 2000) which indicate up to 3500 m of the report area, Early Cretaceous is missing in both Hindhaugh 2) the three, closely-spaced, N-trending lineaments to Creek-1 and Olangolah-1 on the crest of the Otway the southwest of Apollo Bay, and Ranges. 3) the variation in the magnetic response of the The Colac Gravity Low (new name) is the broad, Eumeralla Formation in the Otway Ranges. NE-trending gravity low situated to the northwest of the Otway Ranges Gravity High. This feature is The high frequency, high relief, 'noisy' response over coincident with the Colac Trough and extends the northern half of the study area coincides with southwestward into the Port Campbell Embayment. outcrop/subcrop extent of the Newer Volcanics As can be seen in Enclosure 16, the Colac Gravity Low (Geological Survey of Victoria, 1995). Image is a composite feature made up of a several smaller processing of this high frequency response suggests lows and highs of variable shape and orientation. The the presence of semi-continuous, curvilinear features. two large gravity highs visible at the southwest end of Although some of these trends may represent Older the Colac Gravity Low are the Stoneyford and Volcanics, such as intersected in Warracbarunah-2 Barongarook gravity highs. The Stoneyford Gravity (Tabassi & Menhennitt, 1991), the trends are confined High (Geological Survey of Victoria, 1995) is a large, to areas of outcropping Newer Volcanics. They also triangular-shaped gravity high situated near the occur in the western part of the study area where no 34 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

Older Volcanics have been intersected. The magnetic source for these trends is therefore thought to be thicker volcanics preserved in palaeovalleys cut into the underlying Tertiary sediments. The NNE-trending magnetic highs southwest of Apollo Bay were previously thought to be due to the presence of Tertiary volcanics at a depth of about 1 km (Geological Survey of Victoria, 1995). The lineaments are now thought to be Cambrian greenstone belts (D. Moore pers. comm.) which outcrop approximately 70 km to the NE of Apollo Bay in the Barrabool Hills. The cause of the variation in the magnetic response of the Eumeralla Formation is unclear. As can be seen in Enclosure 17, the Eumeralla Formation can be divided into two zones by a line running N-S through Cape Otway. The eastern zone (E1) is characterised by a thick sequence of mostly non-magnetic material, whereas the western zone (E2) encompassing the western Otway Ranges is an area of high-frequency magnetic response, consistent with moderately magnetic shallow material. Why E2 is more magnetic than E1 which is mapped as the same material is unclear. The boundary between the two zones may represent a change in the magnetite content of the rocks due to a change in the composition of the sandstone, a change in metamorphic grade, or a different burial history. PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 35

8. Petroleum Systems Stoneyford-1, Tirrengowa-1 and Warracbarunah-2, but only the latter has been geochemically sampled in any detail. The Pretty Hill Formation in this well is presently immature to early mature for oil (Rvmax% Three units have source-rock potential in VIC/O-01(1), 0.45 to 0.60%) and appears to have moderate source VIC/O-01(2) and VIC/O-01(3): the Casterton, Pretty rock potential with an average TOC of 1.29% (range Hill and Eumeralla formations. The overlying upper 0.46 to 10.29%), HI of 112 (range 30 to 281) and S1+S2 Late Cretaceous – Tertiary sediments have no of 2.3 (range 0.22 to 29.7). In Stoneyford-1 and source-rock potential, as they are thermally immature Tirrengowa-1, on the other hand, the top of the Pretty over the entire area. Hill Formation is presently mid-mature for oil (Rvmax% 0.72 to 0.84%), which suggests it is probably late-mature (oil) to gas mature in the deeper parts of 8.1 Casterton Formation - Pretty the Gellibrand Trough. Hill Formation 8.2 Eumeralla Formation The Casterton Formation and Pretty Hill Formation in South Australia have been geochemically identified by Padley et al. (1995) and Edwards et al. (1999) as the The Eumeralla Formation has been geochemically source of gas-condensate in the Pretty Hill Formation identified as the source of waxy crudes recovered from in the Katnook, Ladbrook Grove and Haselgrove gas the Windermere Sandstone in Windermere-2, the fields; gas, condensate and oil in Wynn 1; and oil in Heathfield Sandstone in Windermere-1, the Waarre Sawpit-1 and Killanoola-1. Formation in Port Campbell-4, and the Pebble Point Formation in Lindon-1 (McKirdy et al., 1994; Mehin & The Casterton Formation is thought to have excellent Link, 1996, 1997; Edwards et al., 1999). It has also source rock potential in the Penola Trough (Lovibond been identified as the source of gas in the offshore et al., 1995; Hill, 1995) where it has an average TOC of Minerva and La Bella gas fields (Luxton et al., 1995; 4.8% (range 0.4 to 45.9%) and HI of 149 (range 34 to Geary & Reid, 1998). 459) (Mehin & Constantine, 1999). Its genetic potential is also considered very good with an average Two coal seam intervals in the Eumeralla Formation S1+S2 of 10.3 (range 0.2 to 100.9). HI - Tmax data are thought to be the source of these hydrocarbons; one indicate the main kerogen types present are Type II of P. notensis Zone (Aptian) age near the base of the and Type III, which suggest it is potentially both oil unit, and the other of C. striatus Zone (lower Albian) and gas generative. Organic petrology studies age in the middle of the unit (Tupper et al., 1993; (Struckmeyer & Felton, 1990) indicate two types of Mehin & Link, 1996, 1997). The two coal seam coal are present: intervals have been intersected in wells located at either end of the Otway Basin (Preston, 1992a,b,c,d,e,f; 1) a liptinite-rich clarite/inertinite-poor duroclarite Tupper et al., 1993) and appear to be basin-wide in variety, and their extent. The coal seams range from 2 to 3 m in 2) a trimacerite-rich variety. thickness and are separated by mudstones rich in disseminated organic matter. In the former, the main vitrinite maceral subgroup is detrovitrinite with some telovitrinite and minor The maturity of the Eumeralla Formation in gelovitrinite. The detrovitrinite occurs as matrix in VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3) is sporinite, cutinite and suberinite, and is also present illustrated in Figure 14. Surface Rvmax% in dispersed resinite, liptodetrinite and inertinite. The measurements (Cooper et al., 1993; Cooper, 1995a) trimacerite-dominated coals, in comparison, consist of indicate the maturity of the Eumeralla Formation in inertinite-rich duroclarites and vitrinite-rich VIC/O-01(2) increases towards the centre of the Otway clarodurites. Detrovitrinite is the dominant vitrinite. Ranges from immature for oil (Rvmax% <0.5%) to The main liptinite maceral is sporinite. Cutinite, overmature for gas (Rvmax% >2.0%). In VIC/O-01(1), suberinite and resinite are also common. on the other hand, the top of the Eumeralla Formation is largely immature for oil except for in the Barwon The source rock potential of the Pretty Hill Formation Downs Graben where it ranges from early and is also considered good. In Robertson-1, shales within mid-mature for oil (Rvmax% 0.7 to 1.0%). To the east, the Pretty Hill Formation have a TOC of up to 7%, HI in VIC/O-01(3), the top of the Eumeralla Formation of 515 and S1+S2 of 37.26 kg/tonne (Lovibond et al., decreases in maturity from late-mature (oil) on the 1995). The principal kerogens present are Type II and Paraparap High to immature on the Bellarine Type III which suggest it is potentially both oil and gas Peninsula. generative. Rock-Eval data from Stoneyford-1, Tirrengowa-1 and The source rock potential of the Casterton Formation Warracbarunah-2 (Fig. 15) suggests the Eumeralla in VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3) is Formation has very good source rock potential with an uncertain, as it has not yet been intersected in any average TOC of 11.6% (range 0.4 to 40.9%), HI of 140 wells in the study area. The Pretty Hill Formation, in (range 21 to 272), and S1+S2 of 17.9 (range 0.2 to contrast, has been intersected in three wells: 69.9). The HI - Tmax plot indicates it contains mostly 36 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

Type II and Type III kerogen, which suggests the unit predominantly of vitrinite with subordinate quantities is both oil and gas generative. Organic petrology of liptinite and inertinite with minor clarite studies indicate the organic matter is terrestrial in (Struckmeyer & Felton, 1990). Disseminated organic origin (Mehin & Link, 1997) with inertinite the matter-rich claystones within the coal measures dominant maceral (80 to 90%) followed by liptinite contain vitrinite and liptinite in almost equal (5 to 20%) and vitrinite (5 to 10%). The coals are proportions, along with minor inertinite. largely duroclarite in composition and consist

38° S 38° 30' S 39° S

0.51

MATURE (OIL) rom Cooper et al. (1993)

TURE

TURE (OIL)

-MATURE

WITH RvMAX% DA

Y MATURE (OIL)

ACEOUS UPLIFT

TE OIL

POST

144° 30

PETROLEUM WELL 0.5 - 0.7% Rv EARL 0.7 - 1.0% Rv MID MA 1.0 - 1.3% Rv LA 1.3 - 2.0% Rv GAS MA > 2.0% Rv AREA OF MID-CRET

0.45

0.52

0.76

144° E

0.44

0.34 lla Formation in the Eastern Otway Basin. Otway Ranges data f

2.05 MONOCLINE

'E COLAC

143° 30

0.49

0.53 erosion overlain for comparison.

ANTICLINE

FAULT PURRUMBETE

0.41

0.35

0.29 SIMPSON

0.68

0.52

0.42

143° E

0.54

143° E

0.75

0.37 0.75

0.54

0.55

0.57

0.58

Km Outcrop – subcrop maturity (Rvmax%) map for the top of Eumera

0.50 14

39° S nd Cooper (1995a). Areas of Mid-Cretaceous uplift an

38° 30' S Figure Figure a

PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 37 et (m) Depth

0.00 100.00 200.00 300.00 400.00 500.00 600.00 700.00 800.00 900.00 1000.00 1100.00 1200.00

100.00

10.00

TOC %

1.00

0.10 et (m) Depth

0.00 100.00 200.00 300.00 400.00 500.00 600.00 700.00 800.00 900.00 1000.00 1100.00 1200.00

100.00

10.00

S1+S2

1.00

0.10

500

480

460

A-1

440

Tmax(oC)

420

STONEYFORD-1 WARRACBARUNAH-2 TIRRENGOW

III

400 Source rock potential of the Eumeralla Formation in Stoneyford-1, Tirrengowa-1 and Warracbarunah-2.

380 15

100 200 300 400 500 600 YRGNINDEX HYDROGEN Figure Figure 38 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

9 Maturation History account for the mild angular unconformity observed on seismic. This interpretation is supported by palynological data The maturation history of the Eastern Otway Basin (see Fig. 17) which indicates the amount of uplift and has been studied by Duddy (2000) and Aburas & erosion associated with the Mid-Cretaceous inversion Boult (2000). Both workers agree that the main was not evenly spread across the entire Eastern Otway phase of hydrocarbon generation in the area Basin (Constantine, 2001). In Olangolah-1, Stoneyford-1, occurred towards the end of the Early Cretaceous Tirrengowa-1 and Warracbarunah-2, for example, the top from the Otway Group, but differ over whether any of the Eumeralla Formation is P. notensis Zone in age, additional hydrocarbons were generated during the while in Anglesea-1A and Hindhaugh Creek-1 it is Tertiary. C. striatus Zone in age. In these wells, the stratigraphically younger C. paradoxa and P. pannosus Duddy (2000) believes hydrocarbons generation in zones are missing. However, palynological data from the the onshore Eastern Otway Basin ceased during the Barongarook High – Barwon Downs Graben and Tertiary based on his analysis of apatite fission Barrabool Hills – Bellarine Peninsula reveals the top of track and vitrinite reflectance data from the Eumeralla Formation in these areas is C. paradoxa Anglesea-1A, Hindhaugh Creek-1, Olangolah-1, to P. pannosus Zone in age (Dettmann, 1963; MacPhail, Stoneyford-1, Tirrengowa-1 and Warracbarunah-2. 1991, Tickell, 1991b), which suggests the Eumeralla Data from these wells reveal the Eastern Otway Formation in these parts of the basin has not been Basin underwent significant uplift and erosion at uplifted to the same magnitude as the Otway Ranges – the end of the Early Cretaceous (95 Ma) as the Paraparap High or Stoneyford High – Ombersely Trough ° geothermal gradient cooled from 50 to 65 C/Km areas. This raises the possibility that those parts of the ° [Early Cretaceous] to 35 C/Km [Late Cretaceous – Otway Group which did not enter the oil window during Tertiary] Duddy (2000) believes the Otway Group the Early Cretaceous could have been pushed down by was incapable of generating hydrocarbons during the overlying upper Late Cretaceous – Tertiary the Tertiary because the Tertiary section in the succession and heated up high enough to generate ° Eastern Otway (< 800 m @ 35 C/Km) is not thick hydrocarbons in the Tertiary. enough to offset for the amount of Otway Group stripped off in the Mid-Cretaceous (1000 to 3500 m Clearly, additional work needs to be done to better @ 50 to 65°C/Km). constrain the maturation history of the onshore Eastern Otway Basin, especially with respect to the timing of Aburas & Boult (2000), on the other hand, believe potential traps. While there is little doubt the main some parts of the Otway Group in the Eastern phase of hydrocarbon generation occurred towards the Otway could have generated hydrocarbons in the end of the Early Cretaceous, it is possible some Tertiary based on the absence of an angular hydrocarbons may have been generated in the Tertiary. unconformity at the top of the Eumeralla Formation This latter event, however, appears to be restricted in its in some parts of the eastern half of the Colac extent to areas of little or no Mid-Cretaceous uplift and Trough. They believe the absence of this angular erosion where the overlying upper Late Cretaceous – unconformity means the amount of uplift and Tertiary is thick enough to offset any missing Otway erosion across the basin was variable. To calculate Group. These models, however, are one-dimensional and what effect this variation in the amount of uplift are limited to the areas the wells are located in. Further and erosion had on the maturation history of the work needs to be done in order to map the maturity of area, Aburas & Boult (2000) selected two places in the Casterton, Pretty Hill and Eumeralla formations in the Barwon Downs Graben where the angular the subsurface across the entire study area through time, unconformity was absent (Location A: 15 km south and to identify areas where the Otway Group has not of Ingleby-1) and present (Location B: 20 km NE of been seriously affected by the Mid-Cretaceous and Late Ingleby-1). Using parameters from Duddy (2000), Miocene – Pliocene inversion events. the model for Location A (see Fig. 16) indicated the Tertiary section (600 m) is thick enough to generate hydrocarbons from the Otway Group if the Early Cretaceous geothermal gradient was 52°C/Km, but was not thick enough to generate hydrocarbons if the geothermal gradient was any higher (eg. 65°C/Km). The modelling suggested the hydrocarbons would have come from the upper half of the Eumeralla Formation as the lower half of the Eumeralla Formation and underlying Pretty Hill and Casterton formations had previously entered the oil window back in the Early Cretaceous. The model for Location B, on the other hand, indicated the Tertiary section (700 m) was not thick enough to generate hydrocarbons from the Otway Group, but in this model 800 m of Eumeralla Formation was removed at the end of the Early Cretaceous to PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 39

aceous

Maximum Early Cret geothermal gradient MODEL No erosion (65 C/km)

MODEL No erosion Minimum Early Cret geothermal gradient (52 C/km) maturity of the Eumeralla Formation during the s Graben (from Aburas & Boult, 2000). Note slight increase in the 1. Burial history models for Location A in the Barwon Down 16 ate Tertiary in Model Figure Figure L 40 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

38° S 38° 30' S 39° S

T, 2000)

HISTORY PSEUDO WELL

BURIAL GAS FIELD OUTLINE (ABURAS & BOUL

SEISMIC LINE

OTHER SYMBOLS

144° 30

144° 30 retaceous uplift and erosion overlain for

ATER BORE

SITE

POINT

CONTROL

OUTCROP PETROLEUM WELL

GROUNDW

144° E

TUS

144° E

C.PARADOXA P.PANNOSUS P.NOTENSIS

C.STRIA

SPORE-POLLEN ZONES

'E tcrop – subcrop age of the Eumeralla Formation. Areas of Mid-C

143° 30

143° E

Km From Constantine (2001).

5 . Palynological map of the Eastern Otway Basin showing the ou

0 17

39° S omparison Figure Figure c

38° 30 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 41

10 Play Fairways and Play production: Katnook, Ladbrook Grove and Haselgrove (Morton & Sansome, 1995). In the study area, three Types wells intersect the Pretty Hill Formation: Stoneyford-1, Tirrengowa-1 and Warracbarunah-2; all three of which are located in VIC/O-01(1). No porosity- Seven play fairways are thought to have hydrocarbon permeability data is available for the Pretty Hill potential in VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3): Formation in Stoneyford-1 and Tirrengowa-1, but in fractured basement, Pretty Hill Formation, Heathfield Warracbarunah-2 it has an average porosity of 13.3% Sandstone, Barwon River Member, Pebble Point (range 6.4 to 19.0%) and permeability of 23.1 mD Formation, Moomowroong Sand - Wiridjil Gravel, and (range 0.1 to 174.0 mD). These values are not as high Eastern View Formation. Some are proven play as those encountered in Katnook and Ladbrook Grove fairways elsewhere in the Otway Basin, while others fields, but are similar to values obtained from are untested. The following is an outline of each play Garvoc-1, Hawkesdale-1, Pretty Hill-1 and fairway summarising its reservoir quality, distribution Mocamboro-11 to the west of the study area (Messent and potential play types. et al., 1999). The Pretty Hill Formation play fairway is probably limited in its extent to the southeastern half of 10.1 Fractured Basement VIC/O-01(1) and the northern half VIC/O-01(2) (see Fig. 18). Its hydrocarbon potential in VIC/O-01(1) is considered very good as the thickness of the Late Oil and gas has been encountered in fractured Cretaceous – Tertiary section in the southeastern half basement in three Otway Basin wells to date: of the block (600 – 700 m), and the age of the top of the Kalangadoo-1, Sawpit-1 and Gordon-1. Kalangadoo-1 Eumeralla Formation (C. paradoxa - P. pannosus flowed gas from basement (DST 7) at a rate of Zone), is very similar to the Penola Trough. The only 1.5 MMCFD (81% CO2) while Sawpit-1 yielded major difference is seal: in the Penola Trough, the 1.5 BBL of 32 to 35° API oil from fractured Pretty Hill Formation is sealed by Laira Formation metasedimentary phyllitic basement (Moriarty et al., which is absent in VIC/O-01(1). Potential plays in 1995). Gordon-1 yielded 6 BBL of 38° API oil-cut rat- VIC/O-01(1) would most likely be located on the flank hole mud and 1 BBL of oil-cut water. of the Gellibrand Trough in order for them to receive In the onshore Eastern Otway Basin, the fractured charge from source rocks in the deeper portions of the basement play fairway is probably limited in its extent Gellibrand Trough. The main play type in this area to the southeastern half of VIC/O-01(1) and the would most likely be tilted fault blocks with the northern half VIC/O-01(2) (see Fig. 18). The overlying Eumeralla Formation providing vertical- and hydrocarbon potential of this play fairway in cross-fault sealing. The Pretty Hill Formation in the VIC/O 01(1) is considered relatively good. Aburas & Ombersely Trough is unlikely contain hydrocarbons as Boult (2000) identified more than ten prospects with it shielded from source rocks beneath the Barwon fault-dependent closures at the top-basement level on Downs Graben by the Armytage High, and is not the northwestern flank of the Gellibrand Trough and overlain by a thick enough Tertiary section to offset on the Armytage High. These structures would the 1 to 1.5 km of Eumeralla Formation removed by require hydrocarbons to migrate laterally up-dip from the Mid-Cretaceous uplift event. source rocks below the Barwon Downs Graben during The hydrocarbon potential of the Pretty Hill the Early Cretaceous. Formation in VIC/O-01(2), in contrast, is considered In VIC/O-01(2), fractured basement is considered to very low due to the tectonic history of the area. If any have very little hydrocarbon potential due to the suitable traps are present, they would have been tectonic history of the area. If any suitable traps are charged in the Early Cretaceous and would have had present, they would have most likely had been charged to survive in excess of 3500 m of uplift associated with in the Early Cretaceous, and would have had to the Mid-Cretaceous and Late Miocene – Pliocene uplift survive the uplift and erosion associated with the Mid- events. Again, leakage would be a major risk in this Cretaceous and Late Miocene – Pliocene events. area, and reservoir quality is also likely to be a Leakage would be a major risk. The hydrocarbon problem as burial history modelling and drilling potential of fractured basement in VIC/O-01(3) is suggests the Eumeralla Formation in the Otway difficult to assess as the seismic coverage in the block Ranges was possibly in excess of 6 km thick prior to is very poor and it is not known if there are any the Mid-Cretaceous uplift event. suitable structures at this level. The hydrocarbon potential of the Pretty Hill Formation in VIC/O-01(3) is difficult to assess as it has not been intersected in any wells in the block and is 10.2 Pretty Hill Formation difficult to pick on the limited seismic coverage. If present, potential traps would again most likely be tilted blocks plays similar to those in VIC/O-01(1). The Pretty Hill Formation is the major play fairway in the Penola Trough in the South Australian part of the Otway Basin where three gas fields are currently in 42 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

38° S 38° 30' S 39° S

OETA KITCHEN POTENTIAL ORNOGRABEN SORRENTO

Y FAIRWAYS

HILL FM PLA

KITCHEN

OF FRACTURED

ACEOUS UPLIFT

Y SUB-BASIN

144° 30

& PRETTY

144° 30

POTENTIAL

TORQUA

AREA OF MID-CRET

PROBABLE EXTENT SEISMIC COVERAGE BASEMENT

144° E

144° E MONOCLINE

XSO ANKTHNDRN AL CRETACEOUS EARLY DURING KITCHEN MAIN OF AXIS COLAC

143° 30

way map. Prospective areas highlighted in yellow.

ANTICLINE

FAULT

PURRUMBETE SIMPSON

143° E

5 Fractured basement and Pretty Hill Formation play fair

0 18

39° S Figure Figure

38° 30' S PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 43

10.3 Intra-Eumeralla Formation Potential play types in VIC/O-01(3) include stratigraphic pinchouts against basement along the northern margin of the block and anticlines on the Heathfield Sandstone upthrown side of Late Miocene – Pliocene inversion features such as the Barrabool Hills and Bellarine The term ‘Heathfield Sandstone’ was first used by High. These structures would be in an ideal position Wopfner et al. (1971) to describe a 9 m thick porous to receive charge from the coal seams in the Eumeralla quartz sandstone of C. striatus Zone age (Morgan, and Pretty Hill formations if present. 1997) in Heathfield-1. Since then, this name has been used by other workers such as Kopsen & Scholefield The main risk associated with the Heathfield (1990) to describe similar ‘porous’ sandstones of Sandstone play fairway is reservoir quality. In C. striatus Zone or lower C. paradoxa Zone age in Windermere-1, the Heathfield Sandstone has good other wells; one of which (Windermere-1) yielded 31.9 porosity (average 22.9%, range 21.9 to 24.2%) but low BBL of 40.9° API oil and 20.3 BBL of gas-cut water permeability (average 1.4 mD, range 1.2 to 1.6 mD), during a 13 hour test. whereas in Windermere-2 it has a moderate porosity (average 14.0%, range 3.2 to 17.5%) but low It is uncertain if the Heathfield Sandstone is present permeability (average 0.47 mD, range: 0.004 to in the study area because most of the wells that 4.3 mD). This risk is offset to some degree by the close intersect Eumeralla Formation either proximity of VIC/O-01(1) and VIC/O-01(3) to the (a) pass straight into the P. notensis Zone part of the northern margin of the basin. unit without intersecting the stratigraphically The Heathfield Sandstone is not considered a major higher C. striatus, C. paradoxa or P. pannosus play fairway in VIC/O-01(2) as most of the Eumeralla zones first (i.e. Olangolah-1, Stoneyford-1, Formation cropping out in the Otway Ranges is Tirrengowa-1 Warracbarunah-2), or C. striatus Zone in age or older and is mid-mature for (b) only penetrate a short distance into it oil. If it is present, this play fairway is considered to (eg. Ingleby-1). The only wells that penetrate any have very little potential due to the tectonic history of significant thickness of C. striatus or C. paradoxa the area. If suitable traps are present, they would Zone age section in the study area are have most likely had been charged in the Early Anglesea-1A and Hindhaugh Creek-1 (see Encls 2 Cretaceous, and would have had to survive in excess of and 3). However, both wells are located in the 3500 m of uplift associated with the Mid-Cretaceous Anglesea area, so the apparent absence of the and Late Miocene – Pliocene uplift events. Leakage Heathfield Sandstone in these two wells does not would be a serious risk. mean it is absent elsewhere in the report area. This interpretation is supported by the presence of a 2 m thick, medium- to coarse-grained quartz Barwon River Member sandstone bed at Point Lewis approximately 15 km SW of Apollo Bay (see Fig. 1 for location). The Barwon River Member is a potential play fairway The sandstone occurs within a thick sequence of along the northern margin of VIC/O-01(3) (see Fig. 19). Outcrop observations indicate the Barwon River Eumeralla Formation volcaniclastic sandstone and is C. striatus Zone in age; the same age as the Member is a proximal basin-margin fanglomerate with Heathfield Sandstone in Heathfield-1. The bed clasts derived from basement outcropping/subcropping can be traced along strike for a distance of over a few kilometres to the north. At present, the unit is 30 m and is lensoidal in cross-section. only known from its type locality on the northern side of the Barrabool Hills where it is exposed in the core of Petrographic observations indicate the sandstone an anticline, but it is possible that it may also subcrop is very similar in composition to the rest of the volcaniclastic sandstones in the Eumeralla to the east and west along the northern margin of the Formation, but contains an unusually high basin where it would be a potential target in areas of amount of granite-derived quartz. little or no Late Miocene – Pliocene inversion such as between the Barrabool Hills and Bellarine High. At If the Heathfield Sandstone is present in the Eastern present, nothing is known about the Barwon River Otway Basin, its potential as a play fairway is most Member in terms of its permeability or porosity as it likely limited to the southeastern half of VIC/O-01(1) has not yet been petrographically examined in any and the northern half VIC/O-01(2) (see Fig. 19). detail, nor have any plugs been acquired or tested. Potential play types in VIC/O-01(1) could include The coarseness of some horizons, in particular Units A anticlines on the up-thrown side of Late Miocene – (basal breccia-conglomerate) and C (clast-supported Pliocene inversion features such as the Barongarook pebble-conglomerate), suggest it could have excellent High (see lines OGF92A-413 SP1030, OGF92A-415 reservoir potential. The most likely play types SP900, OGF92A-429 SP700), and up-dip pinchouts on associated with this play fairway would be anticlines the flank of the Gellibrand Trough. These structures on the upthrown side of Late Miocene – Pliocene would be in an ideal position to trap oil or gas inversion structures and stratigraphic pinchouts generated from the lower half of the Eumeralla against basement. Formation in the Gellibrand Trough. 44 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

38° S 38° 30' S 39° S

WON RIVER

THFIELD SST

OF HEA OF BAR

ACEOUS UPLIFT

Y FAIRWAY

144° 30

AREA OF MID-CRET

PROBABLE EXTENT PROBABLE EXTENT MEMBER PLA PLAY FAIRWAY

AGE

ONE

ZONE IN

Y ABSENT

TUS

EUMERALLA

PROBABL

HEATHFIELD SANDST

C.STRIA

144° E

ONE

AGE

HIGH

AGE

Y ABSENT

ARMYT

TUS P.NOTENSIS

ZONE IN

EUMERALLA

PROBABL

HEATHFIELD SANDST

C.STRIA MONOCLINE

ONE

AGE

Y ABSENT

TUS P.NOTENSIS COLAC

ZONE IN

143° 30

EUMERALLA

PROBABL

143° 30

HEATHFIELD SANDST

C.STRIA

ANTICLINE

FAULT PURRUMBETE

FM SIMPSON

AY RANGES

P.PANNOSUS

AGE IN THIS

EUMERALLA

ZONE IN

PART OF OTW

C.PARADOXA

143° E

5 Intra-Eumeralla Formation play fairway map. Prospective areas highlighted in yellow.

0 19

39° S Figure Figure

38° 30 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 45

10.4 Base Tertiary Eastern View Formation The Eastern View Formation would be the main The extent of the base Tertiary play fairways in Tertiary play fairway in VIC/O-01(1) and VIC/O-01(3). VIC/O-01(1), VIC/O-01(2) and VIC/O-01(3) Is Although no significant hydrocarbon accumulations illustrated in Figure 20. These play fairways are have been encountered in the Eastern View Formation limited to regions where the underlying Eumeralla in the Otway Basin to date, it is widely considered to Formation is capable of generating hydrocarbons in have excellent reservoir potential with a net to gross of the Tertiary such as the Gellibrand Trough and 25 to 30% and log-derived porosity of up to 30% (Trupp Anglesea Embayment – Bellarine Peninsula. In these et al., 1994; Messent et al., 1999). Potential seals areas, the top of the Eumeralla Formation is include shales within the Eastern View Formation and C. paradoxa to P. pannosus Zone in age and the overlying Demons Bluff Formation. In VIC/O-01(1), overlying upper Late Cretaceous – Tertiary section the primary play type would be Late Miocene – may be thick enough to generate hydrocarbons again Pliocene anticlines similar to those targeted in from the Eumeralla Formation. However, the seismic Ingleby-1, Irrewarra-1 and Nalangil-1. In coverage in these areas is either non-existent or very VIC/O-01(3), the primary play type would be Late poor, and there are very few deep bore-holes. Miocene – Pliocene anticlines similar to the ones present in the southern part of the block near Anglesea. This play type would be a very attractive Pebble Point Formation target to the northeast of Anglesea where the Tertiary section is thickest, but additional seismic data is The Pebble Point Formation is a potential play fairway required to determine if they have closure. in southwest corner of VIC/O-01(1) where a thin wedge extends northeastwards into the Colac Trough from the Port Campbell Embayment. During the 1980s and early 1990s, the Pebble Point Formation was a popular exploration target onshore with numerous shows reported including a 3 m oil (28.8° API) column in Lindon-1 (Tabassi & Davey, 1986), strong oil shows in Curdies-1, Lindon-2 and Wilson-1, and a weak gas show in Fahley-1. Unfortunately, little data is available on the porosity and permeability of the Pebble Point Formation. In Lindon-1, it has an average porosity of 20.8% (range 5.5 to 28.2%) and permeability of 45.3 mD (range 0.02 to 1135 mD). No other data is available. The most likely play type would be Late Miocene – Pliocene anticlines sealed by Pember Mudstone.

Moomowroong Sand - Wiridjil Gravel The Moomowroong Sand and Wiridjil Gravel are potential play fairways in the southwestern corner of VIC/O-01(1). Little is known about either of these units other than they are the same age as the Pebble Point Formation which they grade laterally into. Neither formation has ever been tested, but the presence of hydrocarbons in Pebble Point Formation to the west, and their proximity to potential Early Cretaceous source rocks in the underlying Gellibrand Trough, suggests both units could also be potential reservoirs. The most likely play types would be up-dip pinchouts onto the northwestern flank of the Otway Ranges and Late Miocene – Pliocene anticlines with four-way dip closures in southern half of the Colac Trough. The seal in both areas would be Pember Mudstone. 46 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

38° S 38° 30' S 39° S

OETA KITCHEN POTENTIAL ORNOGRABEN SORRENTO

OF TERTIARY

KITCHEN

Y SUB-BASIN

144° 30

POTENTIAL

TORQUA

AREA OF LATE MIOCENE - PLIOCENE UPLIFT

SEISMIC COVERAGE PROBABLE EXTENT PLAY FAIRWAYS

144° E

GRAVEL

144° E

ZERO EDGES

EASTERN VIEW GRP WIRIDJIL MOOMOWROONG SAND PEBBLE POINT MONOCLINE

'E COLAC

143° 30

ANTICLINE

FAULT

PURRUMBETE SIMPSON

143° E

5 Base Tertiary play fairway map. Prospective areas highlighted in yellow.

0 20

39° S Figure Figure

38° 30' S PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 47

11 SUMMARY uplift and erosion was less extreme and the maturity of the Eumeralla Formation is still relatively low. Potential traps in this area could include Pretty Hill Formation tilted fault blocks and/or intra-Eumeralla 11.1 VIC/O-01(1) Formation faulted stratigraphic plays and anticlines. The main risk associated with these plays would be leakage. If the traps were charged in the Early VIC/O-01(1) is thought to have significant hydrocarbon Cretaceous, the Mid-Cretaceous uplift and erosion potential despite the lack of success to date. In the event may have adversely affected their integrity. past, previous operators of the block have focussed Alternatively, the intra-Eumeralla Formation traps solely on two plays in the northwestern half of the would also be in an ideal position to receive charge block: Pretty Hill Formation tilted fault blocks during the Tertiary via lateral/up-dip migration from (eg. Stoneyford-1, Tirrengowa-1, Warracbarunah-2) Eumeralla Formation source rocks to the west in the and base Tertiary anticlines (eg. Nalangil-1, Ingleby-1, Colac Trough and to the south offshore. Irrewarra-1). Stoneyford-1, Tirrengowa-1 and Warracbarunah-2 are thought to have failed because they are located in a part of the basin that experienced 11.3 VIC/O-01(3) significant uplift and erosion at the end of the Early Cretaceous, which may have breached the traps causing them to leak. Nalangil-1, Ingleby-1 and The hydrocarbon potential of VIC/O-01(3) is difficult to Irrewarra-1, on the other hand, probably failed due to assess as very little is known about its geology and a lack of charge, possibly because the Tertiary section structure. In the past, previous operators have in the vicinity of the wells was not thick enough to focussed on the Eastern View Group in the southwest generate hydrocarbons from the underlying Otway corner of the block in the Anglesea – Torquay area. Group. However, none of the wells sunk in this area were located on structures so they are therefore not valid Seismic observations and maturation models suggest tests. Moreover, most of the wells are very shallow the best area to explore for hydrocarbons in (< 600 m BGL) and bottom in Eastern View Formation VIC/O-01(1) is the Gellibrand Trough in southwestern or Eumeralla Formation. Only two wells penetrate the half of block where the Otway Group is much thicker Eumeralla Formation to any significant depth: and less section is missing. Here, the risk of leakage is Anglesea-1A and Hindhaugh Creek-1. Neither well, less, and the thickness of overlying upper Late though, intersected the Pretty Hill Formation, nor Cretaceous – Tertiary section may be enough to were they located on seismically defined structures. generate hydrocarbons from those parts of the Otway Group that did not enter the oil window back in the The main problem with VIC/O-01(3) is the very poor Early Cretaceous. Potential plays in this part of the seismic coverage, as only 173.4 kms of seismic basin include: (15 lines) has been acquired to date, all of it in the western half of the block. No seismic has been 1) fractured basement highs on the flank of the acquired yet over the Moolap Gravity Low or Bellarine Gellibrand Trough; Peninsula. The presence of weak gas shows in the 2) Pretty Hill Formation tilted fault blocks; Eumeralla Formation in Anglesea-1A (Messent et al., 1999) and Geelong Oil Flow-1, and oil film and scum in 3) intra-Eumeralla Formation up-dip pinchouts and the Eastern View Group in Torquay-6 and –7, is anticlines; and encouraging. The gas is almost certainly derived from 4) Late Miocene – Pliocene anticlines with the Eumeralla Formation, which in Anglesea-1A Palaeocene (Pebble Point Formation, ranges from mid-mature for oil at the top of the unit Moomowroong Sand, Wiridjil Gravel) or Eocene (Rvmax% = 0.76%) to overmature for gas at the base (Eastern View Group) objectives. These play types (Rvmax% = 3.38%). The Eumeralla Formation could are all considered to have significant hydrocarbon also be the source of the oil in Torquay-6 and –7. If so, potential, but have never been tested in this part it is unlikely to have been generated during the of the basin. Tertiary because the Tertiary section in that part of the Anglesea Embayment is probably not thick enough to compensate for the missing Eumeralla Formation. Instead, the oil could have been generated during the 11.2 VIC/O-01(2) Early Cretaceous and leaked out of traps within the Pretty Hill Formation or Eumeralla Formation. It is The Otway Ranges block is considered a high-risk area highly unlikely the oil came from Tertiary source rocks due to the amount of section removed in the Mid- onshore or offshore because these are not mature Cretaceous (up to 3500 m) and Late Miocene – enough to generate oil at the present (Trupp et al., Pliocene (up to 1500 m). Consequently, it is highly 1994). unlikely an active petroleum system is present in this The hydrocarbon potential of VIC/O-01(3), then, is area. If any hydrocarbons are present, they would considered relatively good as the northern and eastern most likely be located in traps beneath the parts of the block do not appear to have been affected southwestern corner of the Otway Ranges where the by the Mid-Cretaceous uplift and erosion event to the 48 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

same degree as VIC/O-01(2). In these areas, the Tertiary section may be thick enough to generate hydrocarbons from the underlying Eumeralla Formation, especially in the Sorrento Graben where the Tertiary is > 1000 m thick in Nepean-37. Moreover, it is also possible hydrocarbons may be present at depth in traps within the Pretty Hill and Eumeralla Formations. However, it is not possible to determine what effect the Late Miocene – Pliocene inversion event would have had on these traps, as well as those in the overlying Tertiary. PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 49

12 Natural/Cultural stream reserves, forests and roads. In addition, for roads, the road manager should be consulted. That Environments and will be either VicRoads or the local Shire, dependent Regulation upon the road. Prior to a permit being awarded a relevant procedure under the Native Title Act 1993 must be undertaken. This may be an agreement under the right to negotiate 12.1 Primary Petroleum Legislation provisions of the Act or entering into an Indigenous Land Use Agreement.

Petroleum exploration of the onshore Eastern Otway Registered aboriginal heritage sites or declared Basin is covered by the Victorian Petroleum Act 1998. archaeological areas are protected under the The Act is largely the same in effect as the Petroleum Commonwealth Aboriginal and Torres Strait Islander Act 1958; however, there are a few key changes Heritage Protection Act 1984 or the Archaeological and relating to bidding on acreage and on the term of an Aboriginal Relics Preservation Act 1972. These sites authority. The gazettal notice will have information are generally small and avoidable. An archaeologist on this. Copies of Act and Regulations are available should be contracted prior to operations to investigate through Anstat Customer Services, PO Box 447, South the area. There are no declared archaeological areas Melbourne, Victoria, 3205, Australia; phone in the offered areas, but there are likely to be (61 3) 9644 2820; fax (61 3) 9645 1926 or free on the registered sites, particularly along the coast. web at http://www.dms.dpc.vic.gov.au. There is a range of subsidiary legislation relating to safety, environment and heritage matters that must also be complied with.

12.2 Access to land

Enclosure 18 shows the land categories in the areas on offer. Access can be obtained to all land except for references area under the Reference Areas Act 1978 and wilderness zones under the National Parks Act 1975. There are four areas of this type in VIC/O-01(1) and four in VIC/O-01(2) (shown in dark green, labelled restricted areas). Access to private land requires the consent of the owner or, if consent cannot be obtained, compensation to be determined by the Victorian Civil and Administration Tribunal. Private land comprises the majority of land in VIC/O-01(1) and VIC/O-01(3), and approximately one-third of land in VIC/O-01(2). Access to a National or State Park or a Coastal Reserve or a Flora and Fauna Reserve requires the consent of the responsible Minister. Access is described in section 40(2) to (6) of the National Parks Act 1975. The first point of contact will be the Chief Ranger for the region. Access to land that is owned by the Victorian Plantations Corporation requires the consent of the Corporation if the operations involve the taking of forest produce. Land that is subject to a licence granted under Part 3A of the Victorian Plantations Corporation Act 1993 is treated as if it were private land and the owner of the land were the licensee. Access to Crown Land that is not in the above categories requires the consent of the Minister for Agriculture and Resources and consultation with the Minister responsible for the land. In general, this means consultation with the Flora, Fauna, Fisheries officer of the regional NRE office. This land includes 50 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

Open-File Reports available from MPV 6. Central Area regional seismic cross-sections 7. Western Area regional seismic sections Permit Reports 8. Surface structural elements map 1:100 000 9. Log correlation cross-section PEP 100 Permit Assessment incorporating interpretation of the PEP 100 (Eastern Sheet 2) Sheet 4. Time Structure Barwon Seismic Survey Map Top Basement 1:50 000 by Hartogen Energy Limited (October 1986) Section 2 Volumetric Analysis by G.J. Blackburn (November 1992) for Gas and Fuel Exploration NL, PEP 100 Eastern Sheet 2 Top Eumeralla Fm. Time includes: Structure Map 1:50 000 by D.J. Morton Hartogen Energy Limited (October1986) 1. Leads and Prospects Map 1:100 000 (Pomborne, Murree Creek, Bungador, Kawarren, Mingawal, PEP 100 Otway Basin Basement Time Structure Map Mountside, Windgeel, Moolerie, Wormbete) 1:50000 Proposed 1991 Lake Murdeduke Seismic Survey by J.Kemmis, Plan No. 16. 2. Base Eumeralla Unconformity (time structure map) 1:25 000 Geophysical Report by S. Sarma (July 1981) for Gas and Fuel Exploration NL, includes: 3. Pretty Hill Sandstone (time structure map) 1:25 000 1. Seismic reflection time at the base of the Otway Group 1:100 000 [PE800868] 4. Pretty Hill Sandstone (time structure map) 1:25 000 2. Bouguer gravity anomaly map 1:100 000 Permit Assessment incorporating interpretation of the 3. Isogam contour map 1:100 000 Barwon Seismic Survey 4. Map of structural leads from gravity, magnetic Section 3 Barwon Seismic Survey- Acquisition by G.J. and seismic survey 1:100000 Blackburn (November 1992) for Gas and Fuel Geological Appraisal of PEP 100 by R.K. Ingram Exploration NL, includes: (August 1983) for Gas and Fuel Exploration NL. No 1. Field Operations Report on the Barwon Seismic enclosures available. Survey by Walcott & Associates Pty Ltd (March Technical Evaluation of Permit P.E.P 100, Victoria, 1992) Technical Report No. 22 by S.M.Yu (June 1987), 2. Field Operation Report 1992 Barwon Seismic includes: Survey by Western Geophysical Australia (March 1. Otway/Torquay Basin Stratigraphy 1992) 2. Top Basement Structure Map TWT Structure Permit Assessment incorporating interpretation of the Map 1:50000 by L.K. Davey (April 1987) for Gas Barwon Seismic Survey & Fuel Exploration NL (Encl. 2) Prospect: South Section 4 Barwon Seismic Survey- Processing Data Stoneyford, Leads: Salt Lake, Mt. Gellibrand, Mt Processing Report by Western Geophysical (not Pleasant, Armitage, Wombete, Winchelsea available) 3. Base of Tertiary Structure Map TWT Structure AVO and Acoustic Impedance Study PEP 100 by Map 1:50000 by L.K. Davey (April 1987) for Gas Simon Petroleum Technology Australia Pty Ltd, Perth & Fuel Exploration (Encl. 3 ) Prospects: Coradjil, (August 1995) for GFE Resources Ltd, includes: Corangamite High, Atkin 1. Seismic section for line G94-11. Permit Assessment incorporating interpretation of the Barwon Seismic Survey Section 1 Geological/Geophysical Summary by G.J. PEP 133 Blackburn (November 1992) for Gas and Fuel Technical Review by J.Paran (March 1999), Boral Exploration NL, includes: Energy Resources Limited, includes: 1. Base Tertiary Unconformity (time structure map) 1. Stoneyford-1 - Tirrengowa-1 Well Correlation 1:100 000 2. Nalangil-1 - Irrewara-1 Well Correlation 2. Base Eumeralla Unconformity (time structure map) 1:100 000 3. Olangolah-1 – Anglesea-1 – Hindhaugh Creek-1 Well Correlation 3. Pretty Hill Sandstone (time structure map) 1:100 000 Regional Interpretation & Structural Mapping Report PEP133 Otway Basin, Victoria by A. N. Aburas, 4. Basement (time structure map) 1:100 000 P.J.Boult, Origin Energy Resources Ltd (May 2000), 5. Eastern Area regional seismic cross-sections includes: PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 51

1. Top Eumeralla Fm Time Structure Map, 6. Geochemistry and well data (added by DNRE 1:100 000 26/07/00) 2. Near Base Eumeralla Fm Time Structure Map, Includes enclosures: 1:100 000 Composite Well Logs (3 parts) 3. Top Pretty Hill SST Time Structure Map, 1:100 000 Attachment to Well Completion Report, includes: 4. Basement Time Structure Map 1:100 000 1. Hindhaugh Creek-1 Formation Testing Service 5. Seismic Dip Line BA92-411 Report by Halliburton Company Thermal, structural and hydrocarbon generation 2. Report Well Velocity Survey Hindhaugh Creek-1 histories based on AFTA and vitrinite reflectance by United Geophysical Corporation results by I.R.Duddy (Geotrack International Pty Ltd Report No. 761, February 2000) for Boral Energy Four-Arm High Resolution Continuous Dipmeter by Schlumberger (September 1969) Dipmeter Computer Processed Results by Petroleum Exploration Wells Schlumberger (December 1969) Anglesea-1A Log Analysis of Sandstones within the Otway Group, Anglesea-1 Well Completion Report includes Hindhaugh Creek-1 by J.W.J. Hardly (March 1971) appendices:

1. Petrological Report by P.W. Bollen, J.Cundill and Olangolah-1 N.A. Meyers Olangolah-1 Well Completion Report includes 2. Preliminary Palynological Examination Oil appendices: Development NL Anglesea-1 Bore by J. Douglas (1963) 1. Report on Electric Logs from Olangolah-1 3. Plant remains Oil Development NL Anglesea-1 2. Sidewalll Core sample Descriptions Well by J. Douglas (1963) 3. Cuttings Descriptions 4. Micropalaeontological Report on Anglesea-1 Well 4. Summary of Drilling Operation by D.J.Taylor (1962) 5. Geochemical evaluation of Olangolah-1 cuttings 5. Examination of core and cuttings from Oil by G.W. Woodhouse (Petroleum Geochemistry Development NL Anglesea-1 Group, W.A.I.T.) Selected data of Rock-Eval Pyrolysis and Vitrinite 6. Palynological report on Olangolah-1 Sidewall Reflectance by Analabs and Keiraville Konsultants cores by M.E. Dettmann (1989) 7. Well velocity analysis Geochemical Source Rock Study Anglesea-1 by Analabs (1987) 8. Organic petrology of a suite of samples from Olangolah-1 by A. C. Cook (Keiraville GC-MS Results for 3 Anglesea-1 Samples by Analabs Konsultants Pty Ltd) (March 1987) High Resolution Dipmeter- Cluster Listing from Geochemistry Report Anglesea-1. Results of the whole Olangolah-1 by Perth Log Interpretation Centre extract GC performed on the additional Anglesea-1 Schlumberger sample, 497ft, core.

Stoneyford-1 Hindhaugh Creek-1 Stoneyford-1 Well Completion Report, includes Hindhaugh Creek-1 Well Completion Report, includes appendices: appendices: 1. Cuttings descriptions by Davey and B.L.Rayner 1. Water Analyses 2. Geochemical Evaluation of Stoneyford-1 cuttings 2. Detailed lithological descriptions of drill cutting by Analabs (March 1984) samples 3. Well Velocity Analysis (W.S.T. Calibration 3. Core descriptions and Analysis Report) 4. List and Interpretation of Logs by K. Millheim Geochemical Evaluation of SWC Samples from (formerly Pursuit Oil NL) Warracbarunah-2, Stoneyford-1 and Tirrengowa-1, 5. Appendix Details of Drill Stem Testing Otway Basin, Victoria (Amdel Report LQ2471) by 52 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

Brian Watson(September 1993) for Gas and Fuel Irrewarra-1 Exploration NL Irrewarra-1 Well Completion Report, Volume 2 (drilling). Tirrengowa-1 Tirrengowa-1 Well Completion Report, includes Warracbarunah-2 appendices: Warracbarunah-2 Well Completion Report (Volume 1), 1. Sidewall core descriptions includes appendices: 2. Sample description 1. Velocity Survey Report Warracbarunah-2 PEP 100 Victoria by Velocity Data Pty Ltd and 3. Palynology Report by R. Morgan VELSEIS Integrated Seismic Technologies (May 4. Source Rock Evaluation, Tirrengowa-1 PEP 100, 1991) Otway Basin by Amdel (June 1987) 2. Petrological Report by Amdel (August 1991) 5. Sonic Calibration Report Tirrengowa-1 by 3. Geochemistry Report by Amdel (August 1991) Schlumberger (March 1987) 4. Palynological and Geochronological Reports by R. Synthetic Seismogram Tirrengowa-1 Morgan (October 1991) Geochemical Evaluation of SWC Samples from 5. Core Analysis Report by Amdel (May 1991) Warracbarunah-2, Stoneyford-1 and Tirrengowa-1, Otway Basin, Victoria (Amdel Report LQ2471) by 6. Water Analysis Report Brian Watson (September 1993) for Gas and Fuel Warracbarunah-2 Well Completion Report (Volume 2) Exploration NL includes enclosures: Wireline Log Evaluation Tirrengowa-1 by Bowler Log 1. Composite Well Log Consulting Services Pty Ltd (November 1987) 2. Mud Log

Nalangil-1 Nalangil-1 Well Completion Report, includes appendices: 1. Sample description 2. Sidewall core descriptions 3. Velocity Survey 4. Synthetic seismograms Ingleby-1 PEP 100 Victoria by VELSEIS Integrated Seismic Technologies Pty Ltd (February 1991) 5. Vitrinite Reflectance by Keiraville Konsultants

Ingleby-1 Ingleby-1 Well Completion Report, includes appendices: 1. Sample descriptions 2. Sidewall core descriptions 3. Velocity Survey Ingleby-1 PEP 100 Victoria by VELSEIS Integrated Seismic Technologies Pty Ltd (January 1991) 4. Synthetic seismograms Ingleby-1 PEP 100 Victoria by VELSEIS Integrated Seismic Technologies Pty Ltd (January 1991) 5. Vitrinite Reflectance by Keiraville Konsultants (hard copy is missing) PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 53

CD-ROM Packages Available from MPV

A variety of data packages relevant to are available from MPV. These include: Victorian Petroleum GIS CD-ROM $30 Victorian Biostratigraphy Reports CD-ROM Package $100 Offshore Otway Scanned Well Completion Report CD-ROM Package $100 The GIS CD-ROM contains seismic navigation data for the whole of Victoria, as well as cultural data (roads, pipelines, rivers, coastline, islands, permit boundaries), seismic survey information spreadsheets and exploration well information spreadsheets. The Biostratigraphy Reports CD-ROM is a two CD set containing scanned copies of biostrata reports (palynology, foraminfera, dinoflagellate, nannoplankton) for the Otway and Gippsland basins. The Otway Basin CD-ROM contains over 240 reports, along with all their tables and enclosures. The reports and enclsoures have all been scanned and converted to PDF. The reports span 19 offshore wells, 74 onshore wells and 122 onshore water bores. The Offshore Otway Scanned Well Completion Report CD-ROM Package is a two CD set containing scanned copies of all offshore well completion reports for the Otway Basin in PDF format. For copies of these data packages, and SEGY, please contact Bob Harms (Manager Information Services) at: [email protected] Ph 03 9412 5015 54 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

References Lower Cretaceous non-marine Strzelecki Group, Gippsland Basin, southeastern Australia. PhD. ABELE, C., 1968. Explanatory notes on the Anglesea Thesis, Monash University, Melbourne (Unpubl.). 1:63 360 geological map. Geological Survey of COOPER, G.T., 1995a. Structural geology, Victoria Unpublished Report 1968/1. thermochronology and tectonic evolution of the Torquay Embayment-Eastern Otway Basin. Ph.D. ABELE, C., 1977. Explanatory notes on the Queenscliff thesis, Monash University (Unpubl.). 1:250 000 geological map. Geological Survey of Victoria Unpublished Report 1977/5. COOPER, G. T., 1995b. Seismic structure and extensional development of the Eastern Otway ABELE, C., 1979. Geology of the Anglesea area, central Basin – Torquay Embayment. Australian coastal Victoria. Geological Survey of Victoria Petroleum Exploration Association Journal, 35(1), Memoir 31 (Unpubl.). pp. 436-450.

ABELE, C., 1984. Geology of the Anglesea area, COOPER, G. T. & HILL, K. C., 1997. Cross-section Victoria: an excursion guide. Geological Survey of Balancing and Thermochronological Analysis of the Victoria Report 1984/51 (Unpubl.). Mesozoic Development of the Eastern Otway Basin. Australian Petroleum Exploration Association ABELE, C., KENLEY, P.R., HOLDGATE, G. & RIPPER, D., Journal. 37(1), pp. 390-414. 1988. Tertiary (Chapter 8). In J.G. Douglas & J.A. Ferguson (eds). Geology of Victoria. Geological COOPER, G. T., HILL, K. C. & WLASENKO, M., 1993. Society of Australia Special Publication 5, Thermal modelling in the eastern Otway Basin. pp. 198-229. Australian Petroleum Exploration Association Journal. 33(1), pp. 205-13. ABURAS, A.N., & BOULT, P.J., 2000. PEP 133 Onshore Otway Basin Regional Interpretation and COULSON, A., 1960. Some structural features of the Structural Mapping Report. Unpublished Origin Barrabool Hills. Proceedings of the Royal Society of Energy Report. Victoria 72, pp.45-52.

ARDITTO, P., & HALL, M., 1994. Field Guide, NGMA DAINTREE, R., 1861. Report on the geology of Bellarine Symposium, April 1994. Geological Survey of and Paywit, with special reference to the probable Victoria Unpublished Report 1994/6. existence of workable coal seams in those parishes. Victoria Parliamentary Papers 1861-62 Vol. 1, BARRETT, A., 1996. PEP 133 Gellibrand Seismic pp.16-23. Survey Interpretation Report. Cultus Petroleum NL internal report. DETTMANN, M.E., 1963. Upper Mesozoic microfloras from south-eastern Australia. Proceedings of the BLAKE, W.J.R., 1980. Geology and hydrology of the Royal Society of Victoria 77, pp.1-148. early Tertiary sediments of the Otway Basin. M.Sc. thesis, La Trobe University, Melbourne DOUGLAS, J.G., ABELE, C., BENEDEK, S., DETTMANN, (Unpubl.). M.E., KENLEY, P.R. & LAWRENCE, C.R., 1988. Mesozoic (Chapter 7). In J.G. Douglas & J.A. BOUTAKOFF, N., 1949. Report on the rocks and Ferguson (eds), Geology of Victoria. Geological inflammable gas collected from the Geelong Flow Society of Australia Special Publication 5, Oil Company’s well near Torquay. Geological pp. 143-144. Survey of Victoria Unpublished Report 1949/25. DOUGLAS, J.G. & LAING, A.C.M., 1976. Explanatory BOWLER, J. M., 1963. Tertiary stratigraphy and notes on the Colac 1:250,000 geological map. sedimentation in the Geelong-Maude area Victoria. Geological Survey of Victoria Report 1976/4. Proceedings of the Royal Society of Victoria 76, pp. 69-137. DUDDY, I. R., 1983. The geology, petrology and geochemistry of the Otway Formation sediments. CANDE, S. C. & MUTTER, J. C., 1982. A revised Ph.D. thesis, Department of Earth Sciences, identification of the oldest sea-floor spreading University of Melbourne (Unpubl.). anomalies between Australia and Antarctica. Earth and Planetary Science Letters 58, pp. 151-60. DUDDY, I. R., 1994. The Otway Basin: thermal, structural, tectonic and hydrocarbon generation CARTER, A.N., 1958. Tertiary Foraminifera from the histories. In D.A.I. Finlayson (ed.), NGMA/PESA Aire district, Victoria. Geological Survey of Victoria Otway Basin Symposium Abstracts, Australian Bulletin 55. Geological Survey Organisation Record 1994/14, pp. 35-42. CONSTANTINE, A., 2001. Sedimentology, stratigraphy and palaeo-environment of the Upper Jurassic- DUDDY, I.R., 2000. PEP 133 Onshore Otway Basin: Thermal, structural and hydrocarbon generation PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 55

histories based on AFTA and vitrinite reflectance GEOLOGICAL SURVEY OF VICTORIA, 1963. Anglesea results. Geotrack Report No. 761 prepared for 1:63 360 geological map. Geological Survey of Boral Energy (Unpubl.). Victoria.

EDWARDS, A. B., 1962. Notes on the geology of the GEOLOGICAL SURVEY OF VICTORIA, 1963. Geelong Lorne District. Proceedings of the Royal Society of 1:63 360 geological map. Geological Survey of Victoria 75, pp. 101-119. Victoria.

EDWARDS, D.S., STRUCKMEYER, H.I.M., BRADSHAW, GEOLOGICAL SURVEY OF VICTORIA, 1967. Sorrento M.T. & SKINNER, J.E., 1999. Geochemical 1:63 360 geological map. Geological Survey of characteristics of Australia’s southern margin Victoria. petroleum systems. Australian Petroleum Exploration Association Journal. 39(1), GEOLOGICAL SURVEY OF VICTORIA, 1971. Queenscliff pp. 297-321. 1:250 000 geological map (First Edition). Department of Mines, Victoria. EDWARDS, J., & TICKELL, S., 1994. Port Campbell Embayment 1:100 000 geological map. Geological GEOLOGICAL SURVEY OF VICTORIA, 1973. Colac Survey of Victoria. 1:250 000 scale geological map (First Edition). Department of Mines, Victoria. EDWARDS, J., PETTIFER, G.R., McDonald, P.A. & Leonard, J.G., 1996. Colac 1:250 000 map geological GEOLOGICAL SURVEY OF VICTORIA, 1977. Portarlington report. Geological Survey of Victoria Report 98. 1:63 360 geological map. Geological Survey of Victoria. ESPLAN, W.A., 1962a. Underground water - Swan Island, Parish of Paywit. Victorian Department of GEOLOGICAL SURVEY OF VICTORIA, 1995. The Mines Report (Unpubl.). stratigraphy, structure, geophysics and hydrocarbon potential of the Eastern Otway Basin, ESPLAN, W.A., 1962b. Underground water resources Victoria. Geological Survey of Victoria Report 103. survey: Bellarine Peninsula. Victorian Department of Mines Report (Unpubl.). GUNN, P. J., MACKEY, T., MITCHELL, J. & CATHRO, D., 1995. Evolution and structuring of the offshore FELTON, E.A., 1992. Sedimentary History of the early Otway Basin, Victoria as delineated by Cretaceous Otway Group, Otway Basin, Australia. aeromagnetic data. Exploration Geophysics Ph.D. thesis, University of Wollongong, Australia 26(2/3), pp. 262-68. (Unpubl.). HILL, A.J., 1995. Source rock distribution and FELTON, E.A., 1997a. A non-marine Lower Cretaceous maturity modelling. In J.G.G. Morton, & J.F. rift-related epiclastic volcanic unit in southern Drexel (eds), 1995 Petroleum Geology of South Australia: the Eumeralla Formation in the Otway Australia. Volume 1: Otway Basin. Mines and Basin. Part I: Lithostratigraphy and depositional Energy, South Australia Report 95/12, pp. 103-126. environments. Australian Geological Survey Organisation Journal of Australian Geology and HILL, K. A., COOPER, G. T., RICHARSON, M. J. & LAVIN, Geophysics 16(5), pp. 717-730. C. J., 1994. Structural Framework of the Eastern Otway Basin: Inversion and interaction between FELTON, E.A., 1997b. A non-marine Lower Cretaceous two major structural provinces. Exploration rift-related epiclastic volcanic unit in southern Geophysics, 25, pp. 79-87. Australia: the Eumeralla Formation in the Otway Basin. Part II: Fluvial systems. Australian HOLDGATE, G.R., SMITH, T.A.G., GALLAGHER, S.J. & Geological Survey Organisation Journal of WALLACE, M.W., 2001. Geology of coal-bearing Australian Geology and Geophysics 16(5), Palaeogene sediments, onshore Torquay Basin, pp. 731-757. Victoria. Australian Journal of Earth Sciences 48, pp.657-679. FOSTER, J. D. & HODGSON, A. J., 1995. Port Campbell reviewed: methane and champagne. Australian HUNT, P.J., 1986. 1986 Experimental Seismic Survey Petroleum Exploration Association Journal 35(1), Final Report, PEP 100 (VIC). Hartogen Energy pp. 418-435. Limited Report (Unpubl.).

GEARY, G.C. & REID, I.S.A., 1998. Geology and KEMMIS, J.L., 1991. Lake Mureduke Seismic Survey, prospectivity of the Offshore Eastern Otway Basin, PEP 100, Otway Basin, Victoria, Volume 1. Gas Victoria - for the 1998 Acreage Release. Victorian and Fuel Exploration NL Report (Unpubl.). Initiative for Minerals and Petroleum Report 55. Department of Natural Resources and KENLEY, P.R., 1974. Comments on the evidence for, Environment. and position of, the Bellarine Fault. Victorian 56 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

Department of Minerals & Energy Report South Australia. Victorian Initiative for Minerals (Unpubl.). and Petroleum Report 43. Department of Natural Resources and Environment. KOPSEN, E. & SCHOLEFIELD, T., 1990. Prospectivity of the Otway Supergroup in the central and western MEHIN, K. & CONSTANTINE, A., 1999. Hydrocarbon Otway Basin. Australian Petroleum Exploration potential of the western onshore Otway Basin in Association Journal 30(1), pp. 263-279. Victoria: 1999 Acreage Release. Victorian Initiative LAVIN, C. J., 1997. A review of the prospectivity of the for Minerals and Petroleum Report 62. Department Crayfish Subgroup in the Victorian Otway Basin. of Natural Resources and Environment. Australian Petroleum Exploration Association Journal 37, pp. 232-244. MESSENT, B.E., COLLINS, G.I.C. & WEST, B.G., 1999. Hydrocarbon prospectivity of the offshore Torquay LAVIN, C.J. & MUSCATELLO, T., 1997. The petroleum Sub-basin; Victoria: Gazettal AreaV99-1. Victorian prospectivity of the Casterton Petroleum System in Initiative for Minerals and Petroleum Report 60. the Victorian Onshore Otway Basin. Victorian Department of Natural Resources and Initiative for Minerals and Petroleum Report 41, Environment. Department of Natural Resources and Environment. MONTAGNAT, D., 1983. The Colac Seismic (1) Survey Final report, PEP 100, Victoria. Gas & Fuel LOVIBOND R., SUTILL, R.J., SKINNER, J.E. & Aburas, Exploration NL Internal Report. A.N., 1995. The hydrocarbon potential of the Penola Trough, Otway Basin. Australian MORGAN, R., 1997. Early Cretaceous/Latest Jurassic Petroleum Exploration Association Journal 35, pp. Palynology Review of the Victorian Otway Basin. 358-371. Unpublished Petroleum Development Report 1997/14. LUXTON, C.W., HORAN, S.T., PICKAVANCE, D.L. & DURHAM, M.S., 1995. The La Bella and Minerva MORIARTY, N. J., TAYLOR, R. J. & DANEEL, G. J., 1995. gas discoveries, offshore Otway Basin. Australian The Sawpit structure-evaluation of a fractured Petroleum Exploration Association Journal 35(1), basement reservoir play in the Otway Basin. pp. 405-417. Australian Petroleum and Exploration Association Journal, 35 (1), pp. 558-78. MACPHAIL, M.K., 1991. Palynological analysis of samples from Ingleby-1. Ingleby-1 WCR. MORTON, J.G.G. & SANSOME, A., 1995. Reservoirs and Seals. In J.G.G. Morton, & J.F. Drexel (eds), MADSEN, A.O., 2000. Tectonic Evolution of the Petroleum Geology of South Australia. Volume 1: Cretaceous – Cenozoic Torquay Embayment, Otway Basin. Mines and Energy, South Australia. Eastern Otway Basin, Victoria, Australia. M.Sc. Report 95/12, pp. 127-139. thesis, Monash University (Unpubl.). PADLEY, D., MCKIRDY, D. M., SKINNER, J. E., SUMMOS, MCKENZIE, D. A., NOTT, R.J., & BOLGER, P.F., 1984: R. E. & MORGAN, R. P., 1995. Crayfish Group Radiometric age determinations. Geological Survey hydrocarbons - Implications for palaeo-environment of Victoria Report 74, pp. 1-65. of Early Cretaceous rift fill in the western Otway Basin. Australian Petroleum Exploration MCKIRDY, D.M., SUMMONS, R.E., PADLEY, D., SERAFINI, Association Journal 35 (1), pp. 517-537. K.M., BOREHAM, C.J. & STRUCKMEYER, H.I.M., 1994. Molecular fossils in coastal bitumens from PARKER, G.J., 1995. Early Cretaceous stratigraphy southern Australia: signatures of precursor biota along the northern margin of the Otway Basin. and source rock environments. Organic Victorian Initiative for Minerals and Petroleum Geochemistry 21(314), pp. 265-286. Report 23. Department of Agriculture, Energy and Minerals. MEDWELL, G. J., 1971. Structures of the Otway Ranges. In H. Wopfner & J.G. Douglas (eds), The PERINCEK, D. & COCKSHELL, C. D., 1995. The Otway Otway Basin of Southeastern Australia, Special Basin: Early Cretaceous rifting to Neogene Bulletin, Geological Surveys of South Australia and inversion. Australian Petroleum Exploration Victoria, pp. 339-358. Association Journal 35, pp.45l-466.

MEHIN, K. & LINK, A. G., 1996. Early Cretaceous REECKMANN, S.A., 1994. Geology of the onshore source rock evaluation for oil and gas exploration, Torquay Sub-basin: a sequence stratigraphic Victorian Otway Basin. Victorian Initiative for approach. In D.A.I. Finlayson (ed.), NGMA/PESA Minerals and Petroleum Report 31. Department of Otway Basin Symposium Abstracts, Australian Natural Resources and Environment. Geological Survey Organisation Record 1994/14, pp. 3-6. MEHIN, K. & LINK, A. G., 1997. Late Cretaceous source rocks offshore Otway Basin, Victoria and PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 57

RICHARDSON, M. J., 1993. Tectono-stratigraphy of the the Otway Basin, Australia. Australian Journal of Colac Trough (Otway Basin), southwestern Earth Sciences 37(3), pp. 351-364. Victoria. M.Sc. preliminary thesis, Monash University (Unpubl.). TABASSI, A. & DAVEY, L.K., 1986. Recovery of oil from the basal Tertiary Pebble Point Formation at PRESTON, J., 1992a. Geochemical evaluation of Lindon-1 - Summary, results and implications. In cuttings samples from Fergusons Hill-1, Otway R.C. Glenie, (ed.), Second South-Eastern Australia Basin, Victoria, Southern Australia. BHP Oil Exploration Symposium, Petroleum Exploration Petroleum Report, June 1992 (Unpubl.). Society of Australia 1985. pp. 241-253.

PRESTON, J., 1992b. Geochemical evaluation of TABASSI, A. & MENHENNITT, C.E., 1991. Well cuttings samples from Ross Creek-1, Otway Basin, Completion Report, Warracbarunah No. 2, Otway Victoria, Southern Australia. BHP Petroleum Basin, Victoria. Geological Survey of Victoria Report, July 1992 (Unpubl.). Unpublished Report 1991/66.

PRESTON, J., 1992c. Geochemical evaluation of an oil THOMPSON, B.R. & LINK, A.G., 1987. Torquay sample from Flaxmans-1, Otway Basin, Victoria. Embayment Workshop 1986: Excursion Notes. BHP Petroleum Report, September 1992 (Unpubl.). Geological Survey of Victoria Unpublished Report 1987/29. PRESTON, J., 1992d. Geochemical evaluation of an oil sample from Port Campbell-1, Otway Basin, TICKELL, S.J., 1991a. Colac and part of Beech Forest Victoria. BHP Petroleum Report, September 1992 1:50 000 geological map. Geological Survey of (Unpubl.). Victoria.

PRESTON, J., 1992e. Geochemical evaluation of TICKELL, S.J., 1991b. Palynology of the Colac 1:250000 cuttings samples from Windermere-2, Otway Basin, Map Sheet. Geological Survey of Victoria Victoria, Southern Australia. BHP Petroleum Unpublished Report 1991/63. Report, September 1992 (Unpubl.). TICKELL, S. J., CUMMINGS, S., LEONARD, J. G. & PRESTON, J., 1992f. Geochemical evaluation of WITHERS, J. A., 1991. Colac 1:50 000 Map Whelk-1, Otway Basin. BHP Petroleum Report, Geological Report. Geological Survey of Victoria October 1992 (Unpubl.). Report 89.

RYAN, S.M., KNIGHT, L.A. & PARKER, G.J., 1995. The TICKELL, S.J., EDWARDS, J. & ABELE, C., 1992. Port stratigraphy and structure of the Tyrendarra Campbell Embayment 1:100 000 map geological Embayment, Otway Basin, Victoria. Victorian report. Geological Survey of Victoria Report 95. Initiative for Minerals and Petroleum Report 15. Department of Agriculture, Energy and Minerals. TRUPP, M. A., SPENCE, K. W. & GIDDING, M. J., 1994. Hydrocarbon Prospectivity of the Torquay Sub- SHAFIK, S., 1983. Calcareous nannofossil biostrati- basin, offshore Victoria. Australian Petroleum graphy: an assessment of foraminiferal and Exploration Association Journal, 34(1), pp. 479-94. sedimentation events in the Eocene of the Otway Basin, southeastern Austral. Bureau of Mineral TUPPER, N. P., PADLEY, D., LOVIBOND, R., DUCKETT, A. Resources Journal of Australian Geology and K. & MCKIRDY, D. M., 1993. A key test of Otway Geophysics 8, pp. 1-17. Basin potential: the Eumeralla-sourced play on the Chama Terrace. Australian Petroleum Exploration SIMON PETROLEUM TECHNOLOGY AUSTRALIA PTY LTD, Association Journal 33(1), pp. 77-93. 1995. AVO and Acoustic Impedence study, PEP 100. WAGHORN, D. B., 1989. Middle Tertiary Calcareous Nannofossils from Aire District, Victoria; a SINGLETON, O.P., 1967. Otway Ranges Region. In J. Comparison with Equivalent Assemblages in South McAndrew & M.A.H. Marsden (eds), 39th ANZAAS Australia and New Zealand. Marine Congress. Excursions Handbook. Australian & Micropaleontology 14, pp. 237-255. New Zealand Association for the Advancement of Science. WOPFNER, H., KENLEY, P.R. & THORNTON, R.C.N., 1971. Hydrocarbon occurrences and potential of SPENCER-JONES, D., 1970. Explanatory notes on the the Otway Basin. In J.G. Douglas & J.A. Ferguson Geelong 1:63,360 geological map. Geological (eds), The Otway Basin of Southern Australia. Survey of Victoria Unpublished Report 1970/1. Geological Survey of South Australia and Victoria Special Bulletin, pp. 385-435. STRUCKMEYER, H. I. M. & FELTON, E. A., 1990. The use of organic facies for refining palaeo- environmental interpretations: A case study from 58 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

MPV Contacts

Open-File Permit Reports, Well Completion Reports and Seismic data

Ms Dee Ninis Petroleum Client Services Petroleum Development Group 7th Floor 240 Victoria Parade East Melbourne VIC 3002 Ph. 9412-5169 Fax: 9412-5156 Email: [email protected]

Geological Maps and Published Geological Survey of Victoria Reports

Mr Kim Ricketts Minerals Business Centre 8th Floor 240 Victoria Parade East Melbourne VIC 3002 Ph. 9412-5103 Fax: 9412-5157 Email: [email protected]

Unpublished Geological Survey of Victoria Reports

Minerals and Petroleum Reference Centre 8th Floor 240 Victoria Parade East Melbourne VIC 3002 Ph. 9412-5145

Gravity and Magnetic Data

Mr David Bibby Technical Officer – Geophysics Geological Survey of Victoria 7th Floor 240 Victoria Parade East Melbourne VIC 3002 Ph. 9412-5017 Fax: 9412-5155 Email: [email protected] PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN 59

18 LAVIN, C.J. & NAIM, H.M., 1995. The structure, Victorian Initiative for Minerals stratigraphy and petroleum potential of the Portland and Petroleum (VIMP) report Trough, Otway Basin, Victoria. series 19 SIMPSON, C.J., SIMS, J.P. & ORANSKAIA, A., 1995. The geology and prospectivity of the Mt Elizabeth area, Eastern Highlands VIMP area. Petroleum Reports in bold typeface 20 ORANSKAIA, A., 1995. A geological interpretation of 1 BUCKLEY, R.W., BUSH, M.D., O'SHEA, P.J., geophysical data over the Mallacoota 1:250 000 sheet, WHITEHEAD, M. & VANDENBERG, A.H.M., 1994. Eastern Highlands VIMP area. NOT RELEASED The geology and prospectivity of the Orbost Survey area. 21 SARMA, S., 1995. Seismic interpreta-tion of the 2 VANDENBERG, A.H.M., WILLMAN, C., offshore Otway Basin, Victoria. HENDRICKX, M., BUSH, M.D. & SANDSTONES, B.C., 22 MEHIN, K. & LINK, A.G., 1995. Early Cretaceous 1995. The geology and prospectivity of the 1993 Mount source rocks of the Victorian onshore Otway Basin. Wellington Airborne survey area. 23 PARKER, G.J., 1995. Early Cretaceous stratigraphy 3 HOLDGATE, G., 1995. The exploration potential of along the northern margin of the Otway Basin, the Permian Numurkah Trough and Ovens Graben, Victoria. Victoria. 24 MOORE, D.H., 1996. A geological interpretation 4 BUSH, M.D., CAYLEY, R.A., ROONEY, R., SLATER, K. & WHITEHEAD M.L., 1995. The geology and of the geophysical data of the Horsham 1:250 000 prospectivity of the southern margin of the Murray Basin. map sheet area. 5 ROONEY, R., 1995. Mineral exploration history of the 25 VANDENBERG, A.H.M., HENDRICKX, M.A., North West VIMP area. WILLMAN, C.E., MAGART, A.P.M., ORANSKAIA, A.N., ROONEY, S. & WHITE, A.J.R., 1996. The geology 6 WILLOCKS, A.J., 1995. An appraisal of the new airborne and prospectivity of the Orbost 1:100 000 map area, surveys over the North West VIMP area. eastern Victoria. 7 WHITEHEAD, M.L., 1995. Geological interpretation of 26 HENDRICKX, M.A., WILLMAN, C.E., MAGART, geophysical data over the Dunolly 1:100 000 sheet. A.P.M., ROONEY, S., VANDENBERG, A.H.M., ORANSKAIA, A. and WHITE, A.J.R. The geology and 8 VANDENBERG, A.H.M., CALUZZI, J., WILLOCKS, prospectivity of the Murrungowar 1:100 000 map area, A.J. & O'SHEA, P.J., 1995. The geology and eastern Victoria. prospectivity of the Mallacoota 1:250 000 sheet, Eastern Highlands VIMP area. 27 BOYLE, R.J., 1996. Mineral exploration history of the Omeo 1:100 000 map area. 9 SANDS, B.C., 1995. A geological interpretation of the geophysical data from the Orbost 1994 airborne survey. 28 HAYDON, S.J., 1996. An appraisal of airborne geophysical data from the 1995 Omeo survey, Victoria. 10 OPPY, I.D., CAYLEY, R.A. & CALUZZI, J., 1995. The geology and prospectivity of the Tallangatta 1:250 000 29 MAHER, S., 1996. Mineral resources of the Dunolly sheet. 1:100 000 map area. 11 CALUZZI, J., 1995. Mineral exploration history of the 30 CHIUPKA, J.W., 1996. Hydrocarbon Play Fairways of Tallangatta 1:250 000 sheet. the Onshore Gippsland Basin, Victoria. 12 SIMONS, B.A., 1995. An appraisal of new 31 MEHIN, K. & LINK, A.G., 1996. Early Cretaceous airborne geophysical data over the Tallangatta source rock evaluation for oil and gas exploration, 1:250 000 map area, Victoria. Victorian Otway Basin. 13 BUSH, M.D., CAYLEY, R.A. & ROONEY, S., 1995. 32 SLATER, K.R., 1996. An appraisal of new airborne The geology and prospectivity of the Glenelg region, geophysical data over the Dargo region, Victoria. North West VIMP area. 33 McDONALD, P.A., 1996. An appraisal of new airborne 14 SLATER, K.R., 1995. An appraisal of new airborne geophysical data over the Corryong region, northeastern geophysical data over the Glenelg region, North West Victoria. VIMP area, Victoria. 34 TWYFORD, R., 1996. An appraisal of airborne 15 RYAN, S.M., KNIGHT, L.A. & PARKER, G.J., 1995. geophysical data from the Murrindal survey, Victoria. The stratigraphy and structure of the Tyrendarra 35 HUTCHINSON, D.F., 1996. Mineral exploration history Embayment, Otway Basin, Victoria. of the Dunolly 1:100 000 map area. 16 KNIGHT, L.A., McDONALD, P.A., FRANKEL, E. & 36 BROOKES, D.J. & BOYLE, R.J., 1996. Mineral MOORE, D.H., 1995. A preliminary appraisal of the exploration history of the Bairnsdale 1:250 000 map area. pre-Tertiary infrabasins beneath the Murray Basin, Northwestern Victoria. 37 MAHER, S., HENDRICKX, M.A., BOYLE, R.J. & BROOKES, D.J., 1996. Geology and prospectivity of the 17 PERINCEK, D., SIMONS, B.A., PETTIFER, G.R. & Bairnsdale 1:250 000 map sheet area. GUNATILLAKE, K., 1995. Seismic interpretation of the onshore Western Otway Basin, Victoria. 60 PROSPECTIVITY OF EASTERN ONSHORE OTWAY BASIN

38 McDONALD, P.A. & WHITEHEAD M.L., 1996. 57 LAVIN, C., 1998. Geology and prospectivity of the Geological interpretation of geophysical data over the western Victorian Voluta Trough - Otway Basin, for Ararat 1:100 000 map sheet. the 1998 Acreage Release. 39 MOORE D.H., 1996. A geological interpretation of the 58 EDWARDS, J., SLATER, K.R. & PARENZAN, M.A., geophysical data of the Ouyen 1:250 000 map sheet area. 1998. Bendigo and part of Mitiamo 1:100 000 map area geological report. 40 BROOKES, D.J., 1996. Mineral exploration history, Ararat and Grampians 1:100 000 map areas. 59 RADOJKOVIC, A., 1998. Mineral exploration history of the Ballarat and Creswick 1:100 000 map areas. 41 LAVIN, C.J., & MUSCATELLO, T., 1997. The petroleum prospectivity of the Casterton Petroleum 60 MESSENT, B.E., COLLINS, G.I.C. & WEST, B.G., System in the Victorian Onshore Otway Basin. 1999. Hydrocarbon prospectivity of the offshore Torquay Subbasin; Victoria: Gazettal AreaV99-1. 42 CHIUPKA, J.W., MEGALLAA, M., JONASSON, K.E. & FRANKEL E., 1997. Hydrocarbon plays and play 61 SMITH, M.A., 1999. Petroleum systems, play fairways fairways of four vacant offshore Gippsland Basin and prospectivity of the Gazettal area V99-2, offshore areas, 1997 acreage release. southern Gippsland Basin, Victoria. 43 MEHIN, K. & LINK, A.G., 1997. Late Cretaceous 62 MEHIN, K., & CONSTANTINE, A.E., 1999. source rocks offshore Otway Basin, Victoria and South Hydrocarbon potential of the western onshore Otway Australia. Basin in Victoria, 1999 acreage release. 44 WILLOCKS, A.J., 1997. An appraisal of airborne 63 HUTCHINSON, D.F., 1999. Mineral exploration history geophysical data from the Castlemaine-Woodend survey, of the Castlemaine, Woodend, Yea and part of Bacchus Victoria. Marsh 1:100 000 map areas. 45 HUTCHINSON, D.F., 1997. Mineral exploration history 64 BATSON, R.A., 1999. Mineral exploration history of the of the Heathcote and Nagambie 1:100 000 map areas. Warburton 1:250 000 map area. 46 MAHER, S., VANDENBERG, A.H.M., McDONALD, 65 SMITH, M.A., BERNECKER, T., LIBERMAN, N., P.A. & SAPURMAS, P., 1997. The Geology and MOORE, D.H. & WONG, D., 2000. Petroleum prospectivity of the Wangaratta 1:250 000 map sheet area. prospectivity of the deep-water gazettal areas V00-3 47 ORANSKAIA, A.N., 1997. Geological interpretation of and V00-4, southeastern Gippsland Basin, Victoria, geophysical features Bendoc 1:100 000 sheet. Australia. 48 ORANSKAIA, A.N., 1997. Geological interpretation of 66 CONSTANTINE, A.E., 2000. Petroleum systems, play geophysical features Cann, Mallacoota and Victorian part fairways and prospectivity of the Gazettal areas V00-1 of Eden 1:100 000 sheets. and V00-2, offshore Otway Basin, Victoria. 49 WILKIE, J.R. & BROOKES, D.J., 1997. Mineral 67 WONG, D. & BERNECKER, T., 2001. Prospectivity exploration history of the Wangaratta 1:250 000 map area. and Hydrocarbon Potential of Area V01-4, Central Deep, Gippsland Basin, Victoria, Australia. 2001 50 McDONALD, P.A., 1997. An appraisal of airborne Acreage Release. geophysical data from the Yea survey, Victoria. 68 CONSTANTINE, A.E., GEARY, G.C. & REID, I.S.A., 51 EDWARDS, J.E., WILLMAN, C.E., McHAFFIE, I.W., 2001. Hydrocarbon Prospectivity of Areas V01-1 to OLSHINA, A. & WILLOCKS, A.J., 1997. The geology V01-3, Offshore Western Otway Basin, Victoria, and prospectivity of the Castlemaine, Woodend, Yea and Australia, 2001 Acreage Release. part of Bacchus Marsh 1:100 000 map sheets. 69 MOORE, D.H. & WONG, D., 2001. Eastern and 52 MAHER, S., MOORE, D.H., CRAWFORD, A.J., Central Gippsland Basin, Southeastern Australia, TWYFORD, R. & FANNING, F.M., 1997. Test drilling Basement Interpretation and Basin Links. on the southern margin of the Murray Basin. 70 CONSTANTINE, A.E. & LIBERMAN, N., 2001. 53 LAVIN, C.J. & MUSCATELLO, T. 1998. The Hydrocarbon Prospectivity Package, Eastern Onshore Casterton Group - Otway Basin Victoria. NOT Otway Basin VIC/O-01(1), VIC/O-01(2) and RELEASED. VIC/O-01(3), 2001 Acreage Release. 54 MEHIN, K. & BOCK, M.P., 1998. Cretaceous source rocks of the onshore Gippsland Basin, Victoria. 55 GEARY, G. & REID, I., 1998. Geology and prospectivity of the offshore eastern Otway Basin, Victoria, for the 1998 Acreage Release. 56 MEGALLAA, M., BERNECKER, T. & FRANKEL, E., 1998. Hydrocarbon prospectivity of the Northern Terrace, offshore Gippsland basin, for the 1998 Acreage Release. . MPVINERALS AND ETROLEUM ICTORIA P.O.BOX 500 EMAST ELBOURNE VIC. 3002 250 VVPICTORIA P ARADE EMAST ELBOURNE VIC. 3002 P03PHONE: 03 9412 5084 F03FAX: 03 9412 5156 WAEB DDRESS: www.nre.vic.gov.au/minpet/