VITRINITE REFLECTANCE SUPPRESSION IN COAL DUE TO A MARINE TRANSGRESSION: CASE STUDY OF THE ORGANIC GEOCHEMISTRY OF THE GRETA SEAM, SYDNEY BASIN

1994 ◽  
Vol 34 (1) ◽  
pp. 241 ◽  
Author(s):  
S. C. George ◽  
J. W. Smith ◽  
D. R. Jardine
Keyword(s):  
Organic Geochemistry ◽  
Vitrinite Reflectance ◽  
Bimodal Distribution ◽  
Atomic Ratio ◽  
Petroleum Exploration ◽  
North West ◽  
The North ◽  
Geochemical Parameters ◽  
Marine Influence ◽  
Geochemical Investigation

Vitrinite reflectance suppression in marine sequences is a major problem facing some petroleum exploration companies. It leads to considerable difficulties in determining thermal maturity in exploration provinces like the North West Shelf of Australia. The Permian Greta seam, northern Sydney Basin, is a classical example of a marine-influenced coal which displays a vitrinite reflectance suppression of 0.25 per cent R0. It is an ideal candidate for detailed organic geochemical investigation of this problem. The amount and composition of extractable hydrocarbons in the coal appear to be only partially related to vitrinite reflectance, so it is unlikely that suppression is directly caused by the adsorption of hydrocarbons into the vitrinite matrix. Vitrinite reflectance is inversely proportional to the H/C atomic ratio, suggesting that the observed suppression is caused by the more perhydrous nature of vitrinite in marine-influenced coals. At the molecular level the marine influence can clearly be distinguished in the top metre of the seam by depleted amounts of n-alkanes with a lower carbon preference index and a slightly bimodal distribution, a lower pristane/phytane ratio and considerably more hopanes and diasteranes. In addition to the peat-derived humic compounds prevalent throughout the seam, these geochemical parameters indicate bacterial re-working of the newly deposited peat and a direct contribution of marinederived lipids at the top of the seam. Fluctuations in n-alkane and isoprenoid distributions and abundances elsewhere in the seam indicate that the depositional environment changed periodically.

THE SUPPRESSION OF VITRINITE REFLECTANCE IN SOME NORTH WEST SHELF WELLS: BARROW-1, JUPITER-1 AND FLAMINGO-1

1992 ◽  
Vol 32 (1) ◽  
pp. 300 ◽  
Author(s):  
R.W.T. Wilkins ◽  
J.R. Wilmshurst ◽  
G. Hladky ◽  
M.V. Ellacott ◽  
C.P. Buckingham
Keyword(s):  
Organic Matter ◽  
Vitrinite Reflectance ◽  
Accurate Determination ◽  
Petroleum Exploration ◽  
Thermal Maturity ◽  
North West ◽  
The North ◽  
The Individual ◽  
Reflectance Data

The sediments of the North West Shelf pose several problems for the accurate determination of thermal maturity by vitrinite reflectance. There are some serious discrepancies between the results of different workers; in some wells there is a surprisingly small increase of reflectance with depth, and it is sometimes difficult to honour these data in thermal maturity modelling. There appear to be two major sources of error in the reflectance data. These are firstly, the effect known as 'suppression' of vitrinite reflectance, and secondly, the difficulty of identifying the vitrinite population in dispersed organic matter.These problems may be addressed by the fluorescence alteration technique which is closely related to vitrinite reflectance but has two special advantages. Firstly, it depends on an analysis of the fluorescence alteration response of a small representative population of organic matter in which the individual macerals need not be identified. Secondly, anomalous vitrinites with suppressed vitrinite reflectance are readily characterized, and the corrected equivalent reflectances determined.The technique has been tested on three North West Shelf petroleum exploration wells, Barrow-1, Jupiter-1 and Flamingo-1. Major discrepancies between measured and equivalent vitrinite reflectance appear to originate in part from the difficulty of identifying the vitrinite population in dispersed organic matter from marine sediments. There is also evidence of suppression of vitrinite reflectance in most samples from Barrow-1, in the Flamingo Group and Plover Formation of Flamingo-1, and in the upper part of the Mungaroo Formation of Jupiter-1.A model is proposed to facilitate the assessment of measured vitrinite reflectance data from Carnarvon or Bonaparte Basin wells. Suppression effects are likely to have influenced measured vitrinite reflectance results from wells for which the strongest data are obtained from the Lower Cretaceous fluvio-deltaic Barrow Group sediments or their equivalents.

THE ROLE OF AMPLITUDE VERSUS OFFSET TECHNOLOGY IN PROMOTING OFFSHORE PETROLEUM EXPLORATION IN AUSTRALIA

2007 ◽  
Vol 47 (1) ◽  
pp. 163 ◽  
Author(s):  
P. E. Williamson ◽  
F. Kroh
Keyword(s):  
Petroleum Exploration ◽  
Gas Field ◽  
North West ◽  
Preliminary Results ◽  
Exmouth Plateau ◽  
The North ◽  
Amplitude Versus Offset ◽  
Cable Lines ◽  
The Cost ◽  
Amplitude Versus

Amplitude versus offset (AVO) technology has proved itself useful in petroleum exploration in various parts of the world, particularly for gas exploration. To determine if modern AVO compliant processing could identify potential anomalies for exploration of open acreage offshore Australia, Geoscience Australia reprocessed parts of four publicly available long cable lines. These lines cover two 2006 acreage release areas on the Exmouth Plateau and in the Browse Basin on the North West Shelf. An earlier study has also been done on two publicly available long cable lines from Geoscience Australia’s Bremer Basin study and cover areas from the 2005 frontier acreage release on the southern margin. The preliminary results from these three reprocessing efforts produced AVO anomalies and were made publicly available to assist companies interested in assessing the acreage. The results of the studies and associated data are available from Geoscience Australia at the cost of transfer.The AVO data from the Exmouth Plateau show AVO anomalies including one that appears to be at the Jurassic level of the reservoir in the Jansz/Io supergiant gas field in adjacent acreage to the north. The AVO data from the Caswell Sub-basin of the Browse Basin show an AVO anomaly at or near the stratigraphic zone of the Brecknock South–1 gas discovery to the north. The geological settings of strata possibly relating to two AVO anomalies in the undrilled Bremer Basin are in the Early Cretaceous section, where lacustrine sandstones are known to occur. The AVO anomalies from the three studies are kilometres in length along the seismic lines.These preliminary results from Geoscience Australiaand other AVO work that has been carried out by industry show promise that AVO compliant processing has value—particularly for gas exploration offshore Australia—and that publicly available long-cable data can be suitable for AVO analysis.

Review of the 2009 offshore petroleum exploration release areas

2009 ◽  
Vol 49 (1) ◽  
pp. 465
Author(s):  
Thomas Bernecker
Keyword(s):  
Deep Water ◽  
South Australia ◽  
Northern Territory ◽  
Data Availability ◽  
Petroleum Exploration ◽  
Release Date ◽  
North West ◽  
The North ◽  
Release Area ◽  
Block Sizes

The Australian Government formally releases new offshore exploration areas at the annual APPEA conference. This year, 31 areas plus two special areas in five offshore basins are being released for work program bidding. Closing dates for bid submissions are either six or twelve months after the release date (i.e. 3 December 2009 and 29 April 2010), depending on the exploration status in these areas is and on data availability. The 2009 release areas are located in Commonwealth waters offshore Northern Territory, Western Australia, South Australia and Victoria, comprising intensively explored areas close to existing production as well as new frontiers. As usual, the North West Shelf features very prominently and is complimented by new areas along the southern margin, including frontier exploration areas in the Ceduna Sub-basin (Bight Basin) and the Otway Basin. The Bonaparte Basin is represented by one release area in the Malita Graben, while five areas are available in the Southern Browse Basin in an under-explored area of the basin. A total of 14 areas are being released in the Carnarvon Basin, with eight areas located in the Dampier Sub-basin, three small blocks in the Rankin Platform and three large blocks on the Northern Exmouth Plateau (these are considered a deep water frontier). In the south, six large areas are on offer in the Ceduna Sub-basin and five areas of varying sizes are being released in the Otway Basin, including a deep water frontier offshore Victoria. The special release areas are located in the Petrel Sub-basin, Bonaparte Basin offshore Northern Territory, and encompass the Turtle/Barnett oil discoveries. The 2009 offshore acreage release offers a wide variety of block sizes in shallow as well as deep water environments. Area selection has been undertaken in consultation with industry, the states and Territory. This year’s acreage release caters for the whole gamut of exploration companies given that many areas are close to existing infrastructure while others are located in frontier offshore regions. As part of Geoscience Australia’s Offshore Energy Security Program, new data has been acquired in offshore frontier regions and have yielded encouraging insights into the hydrocarbon prospectivity of the Ceduna-Sub-basin.

PETROLEUM EXPLORATION PREVIEW FOR 1967

1967 ◽  
Vol 7 (1) ◽  
pp. 16
Author(s):  
M. A. Condon
Keyword(s):  
Financial Incentives ◽  
Petroleum Exploration ◽  
North West ◽  
The North ◽  
Oil Markets ◽  
Before And After ◽  
Timor Sea ◽  
The Government ◽  
Average Size ◽  
The Cost

Exploration for petroleum in Australia paused in 1966 and this pause is likely to continue in 1967.The number of wells drilled and seismic activity will both be slightly less in 1967 than in 1966, but the work will generally be directed to more specific targets. The cost of exploration will be somewhat higher than in 1966.During the year off-shore drilling should increase and it is expected that five mobile rigs will be drilling in the offshore areas by the end of the year. The immediate structural targets available for these rigs are in the Gippsland, Bass and Otway Basins (Victoria-Tasmania), the North-West Shelf and Timor Sea-Bonaparte Gulf, and in the Gulf of Papua.Onshore exploration will be concentrated in the western Australian basins, the Surat Basin, the central Great Artesian Basin, and the Gidgealpa region of the southwestern Great Artesian Basin.The success or otherwise of the off-shore drilling will determine the rate of exploration over the next few years. If important discoveries are made off-shore, these may and probably would result in more intensive exploration of the same stratigraphic intervals onshore.The exploration patterns of Australia and several other countries before and after first commercial discovery are compared. This indicates that Australian discovery came early, as compared with other countries, where production has developed since the war, but that post-discovery effort in Australia has been very much less. The main obvious differences appear to be that in Australia the average size of the exploration concession is very much larger and the number of operators (having regard to the areas concerned) is much smaller, than in the other successful countries.There has been a gradual movement towards reducing the size of operating areas in Australia either by obligatory relinquihment or by farmout, but if discoveries are to be made at a satisfactory rate more operators are needed in every basin.The economic environment of Australia vis-a-vis Middle East oil and oil markets is probably the main basic reason for the peculiar exploratory pattern, which has impelled the Government to provide financial incentives to encourage exploration and development.

A geochemical investigation into the resource potential of the Lawn Hill Platform, northern Australia

2020 ◽  
Vol 60 (2) ◽  
pp. 722
Author(s):  
Amber J. M. Jarrett ◽  
Adam E. H. Bailey ◽  
Christopher J. Boreham ◽  
Tehani Palu ◽  
Lisa Hall ◽  
...  
Keyword(s):  
Organic Geochemistry ◽  
Source Rocks ◽  
Geochemical Data ◽  
Northern Australia ◽  
Hydraulic Stimulation ◽  
Petroleum Potential ◽  
North West ◽  
North Eastern ◽  
Resource Exploration ◽  
Geochemical Investigation

The Lawn Hill Platform (LHP) is a sedimentary province in north-eastern Northern Territory and north-western Queensland that hosts a significant Paleoproterozoic–Mesoproterozoic sequence, often referred to as 'the ‘Isa Superbasin’, and includes the overlying South Nicholson Group. Shale gas resources and base-metals mineralisation are known in north-west Queensland, but the larger basin is underexplored. The Australian Government’s Exploring for the Future (EFTF) 2016−2020 program aims to boost resource exploration in northern Australia. New precompetitive geochemical data obtained in this program includes source rock geochemistry, kerogen kinetics, bitumen reflectance, biomarker and δ13C n-alkanes for understanding the petroleum potential, organic geochemistry of source rocks and fluids, stratigraphic correlations and mineralogy to determine the brittleness of shales. All data and derived reports are accessible on the EFTF portal (www.eftf.ga.gov.au), providing a central location for informed decision making. The results in this study demonstrate fair to excellent source rocks in multiple supersequences that are brittle and favourable to hydraulic stimulation. A comparison to the greater McArthur Basin demonstrates, that although there are many similarities in bulk geochemistry, LHP mudstones are largely heterogeneous, reflecting local variations that may be inherited from variations in contributing biomass, microbial reworking, depositional environment, sediment input and paleoredox conditions.

ECONOMICS OF PETROLEUM EXPLORATION OFFSHORE AUSTRALIA AND SOUTHEAST ASIA

1994 ◽  
Vol 34 (1) ◽  
pp. 887
Author(s):  
Guy Allinson ◽  
Mark Elliston
Keyword(s):  
The Philippines ◽  
The Other ◽  
Petroleum Exploration ◽  
North West ◽  
Field Development ◽  
Country Level ◽  
The North ◽  
Fiscal Regimes ◽  
Low Costs ◽  
Fiscal Regime

The aim of this paper is to assess the economic attractiveness of exploring for crude oil offshore the North West Shelf of Australia by comparison with selected areas offshore Indonesia, Malaysia, Vietnam and the Philippines. In order to do this, the paper examines the technical, quantifiable factors which affect offshore petroleum exploration acreage acquisition decisions at the country level. These factors are historical prospectivity, costs of field development and fiscal regime. Other factors such as political, macro-economic and business risks are not considered.The paper concludes that there are significant differences between the countries as indicated by these measures. Past exploration in the Barrow/Dampier area of the North West Shelf of Australia has shown high levels of success by comparison with the other countries. This relatively high success rate coupled with comparatively low costs of field development and lenient fiscal regimes makes the economics of exploration on the North West Shelf favourable by comparison with those selected areas in the other countries considered.

UPLIFT AND EROSION ON THE ASHMORE PLATFORM, NORTH WEST SHELF: CONFLICTING EVIDENCE FROM MATURATION INDICATORS.

1995 ◽  
Vol 35 (1) ◽  
pp. 333
Author(s):  
G.R. Beardsmore ◽  
P.B. O'Sullivan
Keyword(s):  
Vitrinite Reflectance ◽  
Temperature Drop ◽  
Late Triassic ◽  
Maximum Temperature ◽  
North West ◽  
The North ◽  
Conflicting Evidence ◽  
Uplift And Erosion ◽  
Two Populations ◽  
Track Analysis

The Ashmore Platform is situated to the north of the Browse Basin, on the North West Shelf, off the coast of Western Australia. Apatite fission track analysis (AFTA™), vitrinite reflectance and fluo­rescence alteration of multiple macerals (FAMM) measurements were undertaken on drill cuttings material recovered from the Late Triassic sequence of the oil exploration well, Ashmore Reef-1.Vitrinite reflectance measurements indicate that the Late Triassic sequence is currently experienc­ing maximum temperature. However, reflectance methods were suspected of being unreliable due to suppression of the reflectance, a common problem when dealing with marine influenced sediments. The FAMM technique was used to provide an alter­native maturity estimate using the same speci­mens. The FAMM results suggested that vitrinite reflectance is suppressed and that the true matu­rity is higher than conventional reflectance mea­surements predict.The results also suggest that some of the cuttings material from the sampled level is contaminated by material from higher in the Late Triassic sequence. Both the AFTA™ and FAMM data show bi-modal populations from some depths. It was possible to distinguish between the two populations and esti­mate the maturity of the caved material. FAMM and AFTA™ results together imply that maximum palaeotemperature was reached in the Mid-Creta­ceous, corresponding to a major unconformity in the well.The FAMM results do not agree with published maturity estimates based on conodont alteration indices (CAI), which suggest that temperatures have only recently and rapidly reached current levels. The AFTA™ results can also be interpreted to support this model. Furthermore, sonic velocity data in Miocene limestone suggests post-Miocene erosion, which would be expected to be associated with a temperature drop.

TRENDS AND OUTLOOK FOR EXPLORATION IN WESTERN AUSTRALIA

2001 ◽  
Vol 41 (1) ◽  
pp. 497
Author(s):  
W.L. Tinapple
Keyword(s):  
Western Australia ◽  
Petroleum Industry ◽  
Petroleum Exploration ◽  
North West ◽  
The North ◽  
The Government ◽  
Water Gas ◽  
Increased Activity ◽  
Western Australian ◽  
Positive Results

Petroleum exploration activity in Western Australia over the past decade has been on the increase, boosted by the positive results of many new discoveries, mainly on the North West Shelf but also in frontier areas. Significant discoveries in 1999–2000 resulted from new exploration concepts including deep plays in the Barrow/Dampier Sub-basins, heavy oil plays in the Carnarvon Basin, a deep-water gas play west of Gorgon, large gas/condensate plays in the Browse Basin, and a new gas play in the southern Bonaparte Basin. Discovery itself is a great incentive to the industry to further exploration; however, concerns over oil price, the Australian dollar, markets, policies and perceived prospectivity impact on exploration spending. The short-term outlook for WA is good as a result of existing work commitments including an average of 50 exploration wells to be drilled each year for the next three years. Onshore, where exploration has been subdued, there are signs of increased activity. The Western Australian government is playing a key role in promoting the State through gazettals, promotional activities— conferences and publications, acquiring precompetitive data and making petroleum data more accessible. The government funded Petroleum Exploration Initiatives program is continuing and efforts are being made to facilitate exploration. Sustained high oil prices, improvements in technology and efforts to expedite access to land are just some of the factors which will assist companies in their endeavours. In the longer term, continued growth in Western Australia’s petroleum industry is projected.

Review of the 2008 offshore petroleum exploration release areas

2008 ◽  
Vol 48 (1) ◽  
pp. 359
Author(s):  
Marita Bradshaw
Keyword(s):  
Shallow Water ◽  
Sedimentary Basins ◽  
Water Area ◽  
Petroleum Exploration ◽  
Adjacent Area ◽  
Petroleum Potential ◽  
North West ◽  
The North ◽  
Wide Range ◽  
Offshore Petroleum

Each year the Australian Government releases new offshore opportunities for petroleum exploration. Thirty-five new exploration areas located across five of Australia’s offshore sedimentary basins are offered in the 2008 Release. All the areas are available through a work program bidding system with closing dates for bids at six and 12 months from the date of release. Acreage in the first round closes on 9 October 2008 and includes the more explored areas. The second closing round on 9 April 2009 comprises acreage located in less well explored and frontier regions. The 2008 exploration areas are in Commonwealth waters offshore of Western Australia and the Northern Territory, and in the Territory of the Ashmore and Cartier Islands adjacent area. The 2008 Release focusses on the North West Shelf, as well as offering two new exploration areas in the Vlaming Sub-basin in the offshore Perth Basin. Seven of the new release areas are located in Australia’s major hydrocarbon producing province, the Carnarvon Basin. They include a shallow water area in the western Barrow Sub-basin and another on the Rankin Platform, three areas in deeper water in the Exmouth Sub-basin and two on the deepwater Exmouth Plateau. Six areas are available for bidding in the Browse Basin and another five in the Bedout Sub-basin of the Roebuck Basin. In the Bonaparte Basin, the 15 Release areas are located in shallow water and represent a range of geological settings, including the Vulcan and Petrel sub-basins, Ashmore Platform and Londonderry High. The 2008 Offshore Petroleum Exploration Release of 35 areas in five basins covers a wide range in size, water depth and exploration maturity to provide investment opportunities suited to both small and large explorers. The Release areas are selected from nominations from industry, the States and Territory, and Geoscience Australia. The focus of the 2008 Release is on the North West Shelf where there is strong industry interest in the producing Carnarvon and Bonaparte basins and in the Browse Basin, the home of super-giant gas fields under active consideration for development. Also included in the 2008 Release is the Bedout Sub-basin, in the Roebuck Basin, located on the central North West Shelf, between the hotly contested Carnarvon and Browse basins. In addition, the Release show-cases the southern Vlaming Sub-basin, Perth Basin, where recent studies by Geoscience Australia provide a new understanding of petroleum potential (Nicholson et al, this volume).

CARNARVON BASIN ARCHITECTURE AND STRUCTURE DEFINED BY THE INTEGRATION OF MINERAL AND PETROLEUM EXPLORATION TOOLS AND TECHNIQUES

2002 ◽  
Vol 42 (1) ◽  
pp. 287 ◽  
Author(s):  
L.L. Pryer ◽  
K.K. Romine ◽  
T.S. Loutit ◽  
R.G. Barnes
Keyword(s):  
Seismic Data ◽  
Structural Model ◽  
Mineral Exploration ◽  
Petroleum Exploration ◽  
Block Rotation ◽  
North West ◽  
The North ◽  
Northern Carnarvon Basin ◽  
Migration Pathways ◽  
Carnarvon Basin

The Barrow and Dampier Sub-basins of the Northern Carnarvon Basin developed by repeated reactivation of long-lived basement structures during Palaeozoic and Mesozoic tectonism. Inherited basement fabric specific to the terranes and mobile belts in the region comprise northwest, northeast, and north–south-trending Archaean and Proterozoic structures. Reactivation of these structures controlled the shape of the sub-basin depocentres and basement topography, and determined the orientation and style of structures in the sediments.The Lewis Trough is localised over a reactivated NEtrending former strike-slip zone, the North West Shelf (NWS) Megashear. The inboard Dampier Sub-basin reflects the influence of the fabric of the underlying Pilbara Craton. Proterozoic mobile belts underlie the Barrow Sub-basin where basement fabric is dominated by two structural trends, NE-trending Megashear structures offset sinistrally by NS-trending Pinjarra structures.The present-day geometry and basement topography of the basins is the result of accumulated deformation produced by three main tectonic phases. Regional NESW extension in the Devonian produced sinistral strikeslip on NE-trending Megashear structures. Large Devonian-Carboniferous pull-apart basins were introduced in the Barrow Sub-basin where Megashear structures stepped to the left and are responsible for the major structural differences between the Barrow and Dampier Sub-basins. Northwest extension in the Late Carboniferous to Early Permian marks the main extensional phase with extreme crustal attenuation. The majority of the Northern Carnarvon basin sediments were deposited during this extensional basin phase and the subsequent Triassic sag phase. Jurassic extension reactivated Permian faults during renewed NW extension. A change in extension direction occurred prior to Cretaceous sea floor spreading, manifest in basement block rotation concentrated in the Tithonian. This event changed the shape and size of basin compartments and altered fluid migration pathways.The currently mapped structural trends, compartment size and shape of the Barrow and Dampier Sub-basins of the Northern Carnarvon Basin reflect the “character” of the basement beneath and surrounding each of the subbasins.Basement character is defined by the composition, lithology, structure, grain, fabric, rheology and regolith of each basement terrane beneath or surrounding the target basins. Basement character can be discriminated and mapped with mineral exploration methods that use non-seismic data such as gravity, magnetics and bathymetry, and then calibrated with available seismic and well datasets. A range of remote sensing and geophysical datasets were systematically calibrated, integrated and interpreted starting at a scale of about 1:1.5 million (covering much of Western Australia) and progressing to scales of about 1:250,000 in the sub-basins. The interpretation produced a new view of the basement geology of the region and its influence on basin architecture and fill history. The bottom-up or basement-first interpretation process complements the more traditional top-down seismic and well-driven exploration methods, providing a consistent map-based regional structural model that constrains structural interpretation of seismic data.The combination of non-seismic and seismic data provides a powerful tool for mapping basement architecture (SEEBASE™: Structurally Enhanced view of Economic Basement); basement-involved faults (trap type and size); intra-sedimentary geology (igneous bodies, basement-detached faults, basin floor fans); primary fluid focussing and migration pathways and paleo-river drainage patterns, sediment composition and lithology.

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