TECTONIC CONTROL OF WORLD OIL RESERVES: AUSTRALIA'S POSITION

1992 ◽  
Vol 32 (1) ◽  
pp. 183
Author(s):  
John K. Davidson

Although simple extensional clay models may be representative of grabens tens of kilometres in length, rotational divergence of continents on a sphere produces very different structures. Repeated periods of compression during separation result in wrench faults and compressional anticlines developing along major crustal fractures as a consequence of changes in momentum between a continent and adjacent smaller continental blocks along its rifted margin.The global distribution of rotationally divergent continental margins can be accounted for by asymmetric expansion of the earth. The southern bulge caused by expansion has emphasised non-marine deposition on southern continents with marine deposition more common in the northern hemisphere.Phanerozoic source rocks of the northern hemisphere account for 97 per cent of the world's produced and current reserves of oil. Australia's share of this extreme distribution asymmetry is less than one half of one per cent, yet the country covers five per cent of the Earth's continental crust.The proportion of undiscovered oil reserves outside OPEC and the former USSR is approximately 30 per cent, or some 12 per cent of the world's estimated ultimately recoverable reserve of 2 trillion (Tera) barrels. The majority of Australia's undiscovered reserves lie on the North West Shelf where about 12 per cent of the country's estimated ultimately recoverable reserve could be found.Although Australia is politically stable, lower petroleum taxes would attract exploration for smaller, structurally complex oil fields. While such taxes may be considered politically difficult at present, a by-product of concerted oil exploration would be an enormous increase in Australia's gas reserves to feed the national pipeline grid for the 21st century. Industry can assist increased success rates by greater attention to current technical deficiencies, such as the structural interpretation of seismic lines.

1992 ◽  
Vol 32 (1) ◽  
pp. 289 ◽  
Author(s):  
John Scott

The main potential source rock intervals are generally well defined on the North West Shelf by screening analysis such as Rock-Eval. The type of product from the source rocks is not well defined, owing to inadequacies in current screening analysis techniques. The implications of poor definition of source type in acreage assessment are obvious. The type of product is dependent on the level of organic maturity of the source rock, the ability of products to migrate out of the source rock and on the type of organic material present. The type of kerogen present is frequently determined by Rock-Eval pyrolysis. However, Rock-Eval has severe limitations in defining product type when there is a significant input of terrestrial organic material. This problem has been recognised in Australian terrestrial/continental sequences but also occurs where marine source rock facies contain terrestrially-derived higher plant material. Pyrolysis-gas chromatography as applied to source rock analysis provides, by molecular typing, a better method of estimating the type of products of the kerogen breakdown than bulk chemical analysis such as Rock-Eval pyrolysis.


2016 ◽  
Vol 56 (1) ◽  
pp. 173 ◽  
Author(s):  
Stephen Molyneux ◽  
Jeff Goodall ◽  
Roisin McGee ◽  
George Mills ◽  
Birgitta Hartung-Kagi

Why are the only commercial hydrocarbon discoveries in Lower Triassic and Permian sediments of the western margin of Australia restricted to the Perth Basin and the Petrel Sub-basin? Recent regional analysis by Carnarvon Petroleum has sought to address some key questions about the Lower Triassic Locker Shale and Upper Permian Chinty and Kennedy formations petroleum systems along the shallow water margin of the Carnarvon and offshore Canning (Roebuck/Bedout) basins. This paper aims to address the following questions:Source: Is there evidence in the wells drilled to date of a working petroleum system tied to the Locker Shale or other pre-Jurassic source rocks? Reservoir: What is the palaeogeography and sedimentology of the stratigraphic units and what are the implications for the petroleum systems?The authors believed that a fresh look at the Lower Triassic to Upper Permian petroleum prospectivity of the North West Shelf would be beneficial, and key observations arising from the regional study undertaken are highlighted:Few wells along a 2,000 km area have drilled into Lower Triassic Locker Shale or older stratigraphy. Several of these wells have been geochemically and isotopically typed to potentially non Jurassic source rocks. The basal Triassic Hovea Member of the Kockatea Shale in the Perth Basin is a proven commercial oil source rock and a Hovea Member Equivalent has been identified through palynology and a distinctive sapropelic/algal kerogen facies in nearly 16 wells that penetrate the full Lower Triassic interval on the North West Shelf. Samples from the Upper Permian, the Hovea Member Equivalent and the Locker Shale have been analysed isotopically indicating –28, –34 and –30 delta C13 averages, respectively. Lower Triassic and Upper Permian reservoirs are often high net to gross sands with up to 1,000 mD permeability and around 20% porosity. Depositional processes are varied, from Locker Shale submarine canyon systems to a mixed carbonate clastic marine coastline/shelf of the Upper Permian Chinty and Kennedy formations.


2018 ◽  
Vol 58 (2) ◽  
pp. 871 ◽  
Author(s):  
Melissa Thompson ◽  
Fred Wehr ◽  
Jack Woodward ◽  
Jon Minken ◽  
Gino D'Orazio ◽  
...  

Commencing in 2014, Quadrant Energy and partners have undertaken an active exploration program in the Bedout Sub-basin with a 100% success rate, discovering four hydrocarbon accumulations with four wells. The primary exploration target in the basin, the Middle Triassic Lower Keraudren Formation, encompasses the reservoirs, source rocks and seals that have trapped hydrocarbons in a self-contained petroleum system. This petroleum system is older than the traditional plays on the North-West Shelf and before recent activity was very poorly understood and easily overlooked. Key reservoirs occur at burial depths of 3500–5500 m, deeper than many of the traditional plays on the North-West Shelf and exhibit variable reservoir quality. Oil and gas-condensate discovered in the first two wells, Phoenix South-1 and Roc-1, raised key questions on the preservation of effective porosity and productivity sufficient to support a commercial development. With the acquisition and detailed interpretation of 119 m of core over the Caley Member reservoir in Roc-2 and a successful drill stem test that was surface equipment constrained to 55 MMscf/d, the productive potential of this reservoir interval has been confirmed. The results of the exploration program to date, combined with acquisition of new 3D/2D seismic data, have enabled a deeper understanding of the potential of the Bedout Sub-basin. A detailed basin model has been developed and a large suite of prospects and leads are recognised across a family of hydrocarbon plays. Two key wells currently scheduled for 2018 (Phoenix South-3 and Dorado-1) will provide critical information about the scale of this opportunity.


1994 ◽  
Vol 34 (1) ◽  
pp. 297
Author(s):  
E.L. Horstman

The oil potential of rocks containing inertinite is systematically underestimated by chemical or programmed pyrolysis techniques. Inertinite is measured as organic carbon, but does not contribute to the hydrocarbons produced during pyrolysis. When maceral data is available the measured amount of organic carbon can be recalculated to establish an Hydrogen Index based only on the kerogen which might contribute to oil and gas generation. Inertiniterich rocks that were previously discounted as being only gas prone should be reviewed.Recalculated HI:OI plots prepared from samples from the North West Shelf of Australia indicate the presence of significant amounts of oil-prone kerogen in source rocks previously evaluated as being predominantly gas-prone, upgrading the oil potential of the area.


2007 ◽  
Vol 13 ◽  
pp. 13-16 ◽  
Author(s):  
Henrik I. Petersen ◽  
Hans P. Nytoft

The Central Graben in the North Sea is a mature petroleum province with Upper Jurassic – lowermost Cretaceous marine shale of the Kimmeridge Clay Formation and equivalents as the principal source rock, and Upper Cretaceous chalk as the main reservoirs. However, increasing oil prices and developments in drilling technologies have made deeper plays depending on older source rocks increasingly attractive. In recent years exploration activities have therefore also been directed towards deeper clastic plays where Palaeozoic deposits may act as petroleum source rocks. Carboniferous coaly sections are the most obvious source rock candidates. The gas fields of the major gas province in the southern North Sea and North-West Europe are sourced from the thick Upper Carboniferous Coal Measures, which contain hundreds of coal seams (Drozdzewski 1993; Lokhorst 1998; Gautier 2003). North of the gas province Upper Carboni-ferous coal-bearing strata occur onshore in northern England and in Scotland, but offshore in the North Sea area they have been removed by erosion. However, Lower Carboniferous strata are present offshore and have been drilled in the Witch Ground Graben and in the north-eastern part of the Forth Approaches Basin (Fig. 1A), where most of the Lower Carbon iferous sediments are assigned to the sandstone/shale-dominated Tayport For mation and to the coal-bearing Firth Coal Formation (Bruce & Stemmerik 2003). Highly oil-prone Lower Carboniferous lacustrine oil shales occur onshore in the Midland Valley, Scotland, but they have only been drilled by a single well off shore and seem not to be regionally distributed (Parnell 1988). In the southern part of the Norwegian and UK Central Graben and in the Danish Central Graben a total of only nine wells have encountered Lower Carboniferous strata, and while they may have a widespread occurrence (Fig. 1B; Bruce & Stemmerik 2003) their distribution is poorly constrained in this area. The nearly 6000 m deep Svane-1/1A well (Fig. 1B) in the Tail End Graben encountered gas and condensate at depths of 5400–5900 m, which based on carbon isotope values may have a Carboniferous source (Ohm et al. 2006). In the light of this the source rock potential of the Lower Carboniferous coals in the Gert-2 well (Fig. 1C) has recently been assessed (Petersen & Nytoft 2007).


Author(s):  
Г.П. Яроцкий ◽  
Х.О. Чотчаев

Актуальность рассматриваемой темы в том, что орогенные пояса материковой части Камчатского края насыщены полезными ископаемыми, приуроченных к поясам, образованным последовательным приростом окраин континента от древних с северо-запада к юго-востоку. Такими поясами с месторождениями Ag, Au, Sn, Hg, S являются Северо-Западно-Корякский олигоценовый и Южно-Корякский миоценовый, образованные на северной и южной границе Центрально-Корякской окраины позднемелового континента. Они сформированы в олигоцене и миоцене изолированными вулканогенами локальных андезитовых полей, прорванных гранитоидами тектонической активизации. С ними связаны рудные площади, локализация которых позволит обеспечить прирост запасов разрабатываемых россыпей платиноидов. Цель работы заключается в установлении тектонических закономерностей образования вулканогенов, связанных с ними рудных районов и получения новых данных по их прогнозу. В Северо-Западном поясе оформилась металлогеническая зона с Уннэйваямским, Гайчаваямским и Пальматкинским районами, сопряжёнными с одноименными вулканогенами, в Южно-Камчатском с Ветроваямским вулканогеном. Методология и методы исследования. Методология заключена в глыбово-клавишной структуре литосферы и её земной коры на активных окраинах континента. Методика основана на установлении системной связи структурных элементов геолого-геофизической системы тектоника-вулканогены . Результаты работ и их анализ. Предложена схема закономерностей размещения известных и прогнозируемых рудных районов, узлов юго-запада Корякского нагорья. Они обусловлены глыбово-клавишной тектоникой и локализованы в звеньях серии продольных субпараллельных разновозрастных региональных структур СВ простирания, последовательно наращивающих континент к юго-востоку. Звенья являются дискретными и определяют размеры рудных районов. Рассмотрены выделяемые звенья Северо-Западно-Корякского олигоценового и Южно-Корякского миоценового поясов. В первом СЗ поперечными межглыбовыми разломами литосферы образованы вулканогены гнездового типа. Они возникли на пересечении фундамента позднего мела и южной окраины сопредельной Пенжинской СФЗ поперечными межглыбовыми разломами. В пересечениях образуется литосферный столб вещества гранитоидной активизации верхней мантии и позднемелового осадочного разреза фундамента. Делается вывод, что в Южно-Корякском поясе вулканоген является линейным, образованным заключением линейного СВ Ветроваямского выступа фундамента и чехла между двумя поперечными межглыбовыми разломами. В нём рудоносными вторичными кварцитами создан Ильпинский рудный район с крупными месторождениями самородной серы с Ag, Au, Hg, S. Орогенный вулканизм на активных окраинах континентов сопряжён с основными элементами тектоники и магматизма, создавшими условия образования минерагенических таксонов. На примерах орогенных поясов олигоцена и миоцена очевидна роль геотектонических и металлогенических аспектов авторской методологии глыбово-клавишной структуры литосферы активных окраин. Она эффективна в прогнозе рудных площадей и их оценке последующими геологоразведочными работами. The relevance of the work is that the orogenic belts of the mainland of the Kamchatka Territory are saturated with minerals confined to the belts formed by the successive growth of the continental margins from the ancient ones from the north-west to the south-east. Such belts with deposits of Ag, Au, Sn, Hg, S are the Northwest Koryak Oligocene and South Koryak Miocene, formed on the northern and southern borders of the Central Koryak margin of the Late Cretaceous continent. They are formed in the Oligocene and Miocene by isolated volcanogens of local andesitic fields, broken by granitoids of tectonic activation. Ore areas are associated with them, the localization of which will ensure an increase in the reserves of developed placer deposits. The purpose of the work is to establish tectonic patterns of formation of volcanogens, associated ore regions and obtain new data on their forecast. In the North-Western zone, a metallogenic zone took shape with the Unneivayamsky, Gaichavayamsky and Palmatkinsky regions, associated with the same named volcanogenes, in the South Kamchatka - with the Vetrovayamsky volcanogen. Methodology and research methods. The methodology lies in the block-key structure of the lithosphere and its earths crust on the active margins of the continent. The methodology is based on establishing a systemic connection between the structural elements of the geological and geophysical system tectonics-volcanogens. The results of the work and their analysis. A scheme of patterns of distribution of known and predicted ore regions, nodes of the south-west of the Koryak upland is proposed. They are caused by block-key tectonics and are localized in the links of a series of longitudinal subparallel regionally different age structures of NE strike, successively expanding the continent to the southeast. The links are discrete and determine the size of the ore regions. The distinguished links of the Northwest Koryak Oligocene and South Koryak Miocene belts are considered. In the first northwestern region, nesting volcanogens are formed by transverse interblock faults of the lithosphere. They arose at the intersection of the Late Cretaceous foundation and the southern edge of the adjacent Penzhinsk structural-facial zone with transverse interblock faults. At the intersections, a lithospheric column of granitoid activation matter of the upper mantle and the Late Cretaceous sedimentary section of the basement is formed. It is concluded that the volcanogen in the South Koryak belt, has a linear nature, formed by the conclusion of a linear NE of Vetrovayamsk ledge of the basement and cover between two transverse interblock faults. There ore-bearing secondary quartzites created the Ilpinsk ore region with large deposits of native sulfur with Ag, Au, Hg, S. The orogenic volcanism on the active margins of the continents is associated with the basic elements of tectonics and magmatism, which created the conditions for the formation of minerogenic taxons. The role of geotectonic and metallogenic aspects of the authors methodology of the block-key structure of the active lithosphere margins is evident on the examples of the orogenic Oligocene and Miocene belts. It is effective in forecasting ore areas and evaluating them with subsequent exploration works


2001 ◽  
Vol 41 (1) ◽  
pp. 549
Author(s):  
B.G.K. van Aarssen ◽  
R. Alexander ◽  
R.I. Kagi

The ratio of two trimethylnaphthalenes in sediment extracts can be used to indicate the establishment of a liquid reaction environment in the source rock. The abundance of 1,3,6-TMN relative to 1,3,7-TMN (denoted here as 136/137) is near constant in crude oils. In sediments however, there is a much larger variation. This difference is attributed to the presence of two different reaction environments in the source rock: a liquid organic phase which is the direct precursor of crude oils, and the kerogen / rock matrix onto which compounds are adsorbed. In the liquid reaction environment, methylated naphthalenes undergo many reactions, leading to a near constant value for 136/137. On the other hand, when they are adsorbed onto kerogen or minerals, different reactions prevail and an excess of 1,3,6-TMN is formed. When measured in sediment extracts, the closer 136/137 is to the value typical for oils, the better the liquid reaction environments established in the source rock. This concept was used to study the behaviour of 136/ 137 with depth in 10 sedimentary sequences from the North West Shelf. The results showed that sediments from several wells were capable of establishing a liquid reaction environment, a necessary step in the formation of oil. Results from other wells indicated that little or no liquid reaction environment could be established, suggesting that these sediments were unlikely to be capable of oil formation. The 136/137 parameter is a convenient indicator for determining the extent to which the liquid reaction environment has been established in the source rock and may be useful in determining oil generation potential.


2017 ◽  
Vol 57 (2) ◽  
pp. 744
Author(s):  
Jarrad Grahame ◽  
Emma Cairns ◽  
Stephanie Roy

CGG Multi-Client & New Ventures, in collaboration with CGG Robertson, has undertaken a new comprehensive study of the Triassic paleogeography and petroleum systems of the North West Shelf (NWS) including the Northern Carnarvon, Roebuck, Browse and Bonaparte basins. The key objectives of the study were to enhance the understanding of the prospectivity of NWS Triassic petroleum systems, develop new paleogeography maps, establish evidence for Triassic marine-derived source rocks and investigate the prospectivity of Late Triassic carbonate reef complexes. The study comprises new biostratigraphic analyses, quantitative evaluation by scanning electron microscopy (QEMSCAN®) analyses, core logging, 1D and 2D modelling of key wells and seismic sections, plate reconstructed paleogeography and play mapping. Of key relevance to this study is the paleo-depositional framework and subsequent structuring of Triassic successions throughout the NWS basins in the context of petroleum system development.


1995 ◽  
Vol 12 (2) ◽  
pp. 177-194 ◽  
Author(s):  
J.P. Herbin ◽  
J.L. Fernandez-Martinez ◽  
J.R. Geyssant ◽  
A.El. Albani ◽  
J.F. Deconinck ◽  
...  

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