HYDROCARBON GASES IN SEAFLOOR SEDIMENTS, OTWAY AND GIPPSLAND BASINS: IMPLICATIONS FOR PETROLEUM EXPLORATION

1989 ◽  
Vol 29 (1) ◽  
pp. 96 ◽  
Author(s):  
G.W. O'Brien ◽  
D.T. Heggie
Keyword(s):  
Liquid Hydrocarbon ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Gas Content ◽  
Hydrocarbon Gases ◽  
Near Surface ◽  
Wet Gas ◽  
Well Data ◽  
Seafloor Sediments ◽  
Gippsland Basin

During April- May 1988, the BMR research vessel Rig Seismic carried out a 21- day geochemical and sedimento- logical research program in the Otway (17 days) and Gippsland (4 days) Basins. The concentrations and molecular compositions of light hydrocarbon gases (C1- C4) were measured in sediments at 203 locations on the continental shelf and upper continental slope: the presence of thermogenic hydrocarbons was inferred from the molecular compositions of the gas mixtures. Thermogenic hydrocarbons were identified in near- surface sediments at 32 locations in the Otway Basin; 6 of these locations were on the Crayfish Platform, 7 were on the Mussel Platform and 17 were in the Voluta Trough. Thermogenic hydrocarbons were identified at 10 locations in the Gippsland Basin. Data from the Otway Basin indicated that total C1- C4 gas concentrations were higher in the Voluta Trough than on the basin margins, probably because intense faulting in the trough facilitates gas migration from deeply buried source rocks and/or reservoirs to the seafloor. However, anomalies were detected where the Tertiary sequence was thick and relatively unfaulted. The wet gas contents of the anomalies were highest on the basin margins, lower in the Voluta Trough and co- varied with the depth of burial of the basal Early Cretaceous sedimentary sequence. These data, when integrated with geohistory, thermal maturation modelling and well data, suggest that the areas with the best potential for liquid hydrocarbon entrapment and preservation are the Crayfish Platform and the inshore part of the Mussel Platform. In contrast, the Late Cretaceous Sherbrook Group and much of the Voluta Trough appear to be gas prone.Thermogenic anomalies in the Gippsland Basin were concentrated within and along the margins of the Central Deep where mature Latrobe Group source rocks are present. The wet gas content of these anomalies was variable, which is consistent with the spatial heterogeneity of hydrocarbon accumulations in the Gippsland Basin.

A QUEST FOR A NEW PARAMETER IN PETROLEUM EXPLORATION GEOCHEMISTRY

1987 ◽  
Vol 27 (1) ◽  
pp. 98 ◽  
Author(s):  
J.W. Smith ◽  
T.D. Gilbert
Keyword(s):  
Critical Factor ◽  
Liquid Hydrocarbon ◽  
General Concept ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Hydrocarbon Gases ◽  
Petrographic Composition ◽  
Exploration Geochemistry ◽  
Hydrous Pyrolysis ◽  
Rock Parameters

Primary Australian terrestrially-derived crudes are characterised by high wax and n-alkane contents. These characteristics, as determined by hydrogenation and hydrous pyrolysis, appear to be unrelated to either the chemical or petrographic compositions of Victorian brown coal lithotypes. Furthermore, since relationships between chemical and petrographic composition are obscure, a re-examination of current concepts which relate these established source rock parameters to liquid hydrocarbon generating potentials is warranted.The content of thermally stable, longer-chain, n-alkyl components in source rocks is introduced as the critical factor in determining whether these rocks have the potential to generate typical Australian waxy crudes or hydrocarbon gases. Modifications to this general concept are required by the thermal stability of directly substituted longer-chain n-alkyl aromatics and hydroaromatics. These appear to be sources of light hydrocarbons and gases, rather than oils.Inherent weaknesses in the experimental techniques of hydrogenation and hydrous pyrolysis have hindered the collection of data, but the concept that n-alkane potential is a critical factor in determining the petroleum-generating potential of immature source rocks is being pursued using techniques modified for the determination of their total heteroatom-bonded n-alkyl contents.

scholarly journals Oil generation from coal source rocks: the influence of depositional conditions and stratigraphic age

2005 ◽  
Vol 7 ◽  
pp. 9-12 ◽  
Author(s):  
Henrik I. Petersen
Keyword(s):  
North Sea ◽  
Liquid Hydrocarbon ◽  
Source Rocks ◽  
Hydrocarbon Generation ◽  
Oil Generation ◽  
Generation Capacity ◽  
The Subject ◽  
Coal Composition ◽  
Gippsland Basin ◽  
Australasian Region

Although it was for many years believed that coals could not act as source rocks for commercial oil accumulations, it is today generally accepted that coals can indeed generate and expel commercial quantities of oil. While hydrocarbon generation from coals is less well understood than for marine and lacustrine source rocks, liquid hydrocarbon generation from coals and coaly source rocks is now known from many parts of the world, especially in the Australasian region (MacGregor 1994; Todd et al. 1997). Most of the known large oil accumulations derived from coaly source rocks have been generated from Cenozoic coals, such as in the Gippsland Basin (Australia), the Taranaki Basin (New Zealand), and the Kutei Basin (Indonesia). Permian and Jurassic coal-sourced oils are known from, respectively, the Cooper Basin (Australia) and the Danish North Sea, but in general only minor quantities of oil appear to be related to coals of Permian and Jurassic age. In contrast, Carboniferous coals are only associated with gas, as demonstrated for example by the large gas deposits in the southern North Sea and The Netherlands. Overall, the oil generation capacity of coals seems to increase from the Carboniferous to the Cenozoic. This suggests a relationship to the evolution of more complex higher land plants through time, such that the highly diversified Cenozoic plant communities in particular have the potential to produce oil-prone coals. In addition to this overall vegetational factor, the depositional conditions of the precursor mires influenced the generation potential. The various aspects of oil generation from coals have been the focus of research at the Geological Survey of Denmark and Greenland (GEUS) for several years, and recently a worldwide database consisting of more than 500 coals has been the subject of a detailed study that aims to describe the oil window and the generation potential of coals as a function of coal composition and age.

scholarly journals Inversion tectonics: a brief petroleum industry perspective

2020 ◽  
Author(s):  
Gábor Tari ◽  
Didier Arbouille ◽  
Zsolt Schléder ◽  
Tamás Tóth
Keyword(s):  
Petroleum Industry ◽  
Structural Complexity ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Data Sets ◽  
Hydrocarbon Generation ◽  
Seismic Reflection Data ◽  
Reflection Seismic ◽  
Reflection Data ◽  
Well Data

Abstract. The concept of structural inversion was introduced in the early 1980s. By definition, an inversion structure forms when a pre-existing extensional (or transtensional) fault controlling a hangingwall basin containing a syn-rift or passive fill sequence subsequently undergoes compression (or transpression) producing partial (or total) extrusion of the basin fill. Inverted structures provide traps for petroleum exploration, typically four-way structural closures. As to the degree of inversion, based on large number of worldwide examples seen in various basins, the most preferred petroleum exploration targets are mild to moderate inversional structures, defined by the location of the null-points. In these instances, the closures have a relatively small vertical amplitude, but simple in a map-view sense and well imaged on seismic reflection data. Also, the closures typically cluster above the extensional depocentres which tend to contain source rocks providing petroleum charge during and after the inversion. Cases for strong or total inversion are generally not that common and typically are not considered as ideal exploration prospects, mostly due to breaching and seismic imaging challenges associated with the trap(s) formed early on in the process of inversion. Also, migration may become tortuous due to the structural complexity or the source rock units may be uplifted above the hydrocarbon generation window effectively terminating the charge once the inversion occurred. For any particular structure the evidence for inversion is typically provided by subsurface data sets such as reflection seismic and well data. However, in many cases the deeper segments of the structure are either poorly imaged by the seismic data and/or have not been penetrated by exploration wells. In these cases the interpretation of any given structure in terms of inversion has to rely on the regional understanding of the basin evolution with evidence for an early phase of substantial crustal extension by normal faulting.

scholarly journals Tectonosedimentary framework of Upper Cretaceous –Neogene series in the Gulf of Tunis inferred from subsurface data: implications for petroleum exploration

2017 ◽  
Vol 68 (2) ◽  
pp. 97-108 ◽  
Author(s):  
Wissem Dhraief ◽  
Ferid Dhahri ◽  
Imen Chalwati ◽  
Noureddine Boukadi
Keyword(s):  
Seismic Data ◽  
Upper Cretaceous ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Tectonic Activity ◽  
Petroleum Systems ◽  
Subsurface Structures ◽  
Gulf Of Tunis ◽  
Northeastern Tunisia ◽  
Well Data

Abstract The objective and the main contribution of this issue are dedicated to using subsurface data to delineate a basin beneath the Gulf of Tunis and its neighbouring areas, and to investigate the potential of this area in terms of hydrocarbon resources. Available well data provided information about the subsurface geology beneath the Gulf of Tunis. 2D seismic data allowed delineation of the basin shape, strata geometries, and some potential promising subsurface structures in terms of hydrocarbon accumulation. Together with lithostratigraphic data obtained from drilled wells, seismic data permitted the construction of isochron and isobath maps of Upper Cretaceous-Neogene strata. Structural and lithostratigraphic interpretations indicate that the area is tectonically complex, and they highlight the tectonic control of strata deposition during the Cretaceous and Neogene. Tectonic activity related to the geodynamic evolution of the northern African margin appears to have been responsible for several thickness and facies variations, and to have played a significant role in the establishment and evolution of petroleum systems in northeastern Tunisia. As for petroleum systems in the basin, the Cretaceous series of the Bahloul, Mouelha and Fahdene formations are acknowledged to be the main source rocks. In addition, potential reservoirs (Fractured Abiod and Bou Dabbous carbonated formations) sealed by shaly and marly formations (Haria and Souar formations respectively) show favourable geometries of trap structures (anticlines, tilted blocks, unconformities, etc.) which make this area adequate for hydrocarbon accumulations.

UNDERSTANDING SOURCE, DISTRIBUTION AND PRESERVATION OF AUSTRALIAN NATURAL GAS: A GEOCHEMICAL PERSPECTIVE

2001 ◽  
Vol 41 (1) ◽  
pp. 523 ◽  
Author(s):  
C.J. Boreham ◽  
J.M. Hope ◽  
B. Hartung-Kagi
Keyword(s):  
Organic Matter ◽  
Natural Gas ◽  
Isotopic Composition ◽  
Carbon Isotopic Composition ◽  
Source Rocks ◽  
Source Distribution ◽  
Hydrocarbon Gases ◽  
Carbon Isotopic ◽  
Wet Gas ◽  
Gaseous Hydrocarbons

Natural gases from all of Australia’s major gas provinces in the Adavale, Amadeus, Bass, Bonaparte, Bowen/ Surat, Browse, Canning, Carnarvon, Cooper/Eromanga, Duntroon, Gippsland, Otway and Perth basins have been examined using molecular and carbon isotopic compositions in order to define their source, maturity and secondary alteration processes.The molecular compositions of the gaseous hydrocarbons range from highly wet to extremely dry. On average, reservoired gases predominantly derived from land plants are slightly wetter than those derived from marine sources. The non-hydrocarbon gases CO2 and N2 were sourced from both inorganic and organic materials. A mantle and/or igneous origin is likely in the majority of gases with CO2 contents >5%. For gases with lower CO2 contents, an additional organic input, associated with hydrocarbon generation, is recognised where δ13C CO2 is A strong inter-dependency between source and maturity has been recognised from the carbon isotopic composition of individual gaseous hydrocarbons. This relationship has highlighted some shortcomings of common graphical tools for interpretation of carbon isotopic data. The combination of the carbon isotopic composition of gaseous hydrocarbons and the low molecular weight nalkanes in the accompanying oil allows our knowledge of oil-source correlations and oil families to be used to correlate gases with their sources. This approach has identified source rocks for gas ranging in age from the Ordovician in the Amadeus Basin to Late Cretaceous- Early Tertiary sources in the Bass and Gippsland basins. The carbon isotopic composition of organic matter, approximated using the δ13C of iso-butane, shows a progressive enrichment in 13C with decreasing source age, together with marine source rocks for gas being isotopically lighter than those from land plant sources. The Permian was a time when organic matter was enriched in 13C and isotopically uniform on a regional scale.Secondary, in-reservoir alteration has played a major role in the modification of Australian gas accumulations. Thus, biodegradation, prominent in the Bowen/Surat, Browse, Carnarvon and Gippsland basins, is found in both hydrocarbon and non-hydrocarbon gases. This is recognised by an increase in gas dryness, elevated isoalkane to n-alkane ratio, differential increase in δ13C of the individual wet gas components, a decrease in δ13C of methane and a reduction in CO2 content concomitant with enrichment in 13C. Evidence of water-washing has been identified in accumulations in the Bonaparte and Cooper/Eromanga basins, resulting in an increase in the wet gas content. Seal integrity is also a major risk for the preservation of natural gas accumulations, although its effect on gas composition is only evident in extreme cases, such as the Amadeus Basin, where preferential leakage of methane in the Palm Valley field has resulted in the residual methane becoming enriched in 13C.The greater mobility of gas within subsurface rocks can have a detrimental effect on oil composition whereby gas-stripping of light hydrocarbons is common amongst Australian oil accumulations. Alternatively, the availability of gas, derived from a source rock common to or different from oil, was likely to have been a prime factor controlling the regional distribution of oil, whereby mixing of both results in increased oil mobility and can lead to a greater access to the number and types of traps in the subsurface.

THE GEOLOGY AND HYDROCARBON POTENTIAL OF THE NORTH-WESTERN OFFICER BASIN

1985 ◽  
Vol 25 (1) ◽  
pp. 52
Author(s):  
Bruce J. Phillips ◽  
Alan W. James ◽  
Graeme M. Philip
Keyword(s):  
Seismic Data ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Hydrocarbon Potential ◽  
Aeromagnetic Data ◽  
The North ◽  
Carbonate Sequence ◽  
Well Data ◽  
Regional Gravity ◽  
North Western

Recent petroleum exploration in EP 186 and EP 187 in the north-western Officer Basin has greatly increased knowledge of the regional stratigraphy, structure and petroleum prospectivity of the region. This exploration programme has involved the drilling of two deep stratigraphic wells (Dragoon 1 and Hussar 1) and the acquisition of 1438 km of seismic data. Integration of regional gravity and aeromagnetic data with regional seismic and well data reveals that the Gibson Sub-basin primarily contains a Proterozoic evaporitic sequence. In contrast, the Herbert Sub-basin contains a Late Proterozoic to Cambrian clastic and carbonate sequence above the evaporites. This sequence, which was intersected in Hussar 1, is identified as the primary exploration target in the Western Officer Basin. The sequence contains excellent reservoir and seal rocks in association with mature source rocks. Major structuring of the basin has also been caused by compressive movements associated with the Alice Springs Orogeny. The northwestern Officer Basin thus has all of the ingredients for the discovery of commercial hydrocarbons.

Investigation of geochemical characteristics of hydrocarbon gas and its implications for Late Miocene transpressional strength — A study in the Fangzheng Basin, Northeast China

2018 ◽  
Vol 6 (1) ◽  
pp. T83-T96 ◽  
Author(s):  
Bo Liu ◽  
Dongqi Yan ◽  
Xiaofei Fu ◽  
Yanfang Lü ◽  
Lei Gong ◽  
...  
Keyword(s):  
Late Miocene ◽  
Stable Carbon Isotopes ◽  
Active Faults ◽  
Source Rocks ◽  
Type Ii ◽  
Gas Generation ◽  
Hydrocarbon Gases ◽  
Type Iii ◽  
Wet Gas ◽  
Hydrocarbon Gas

We have assessed the genetic types of hydrocarbon gas in the Fangzheng Basin by analyzing the effects of geologic settings on gas generation, kerogen types in source rocks, gas compositions, stable carbon isotopes of individual alkanes, and biomarkers in gas-associated oil. The primary compounds of source rocks in the Eocene Xinancun Formation and Paleocene Wuyun Formation are found as type II and III kerogens, respectively. The hydrocarbon gas in the Fangzheng Basin can be classified into three families. Family I is affected by biodegradation, and it is dry gas generated from low-maturity lacustrine mudstones (i.e., oil-prone source rocks) of the Xinancun Formation. Family II is coal-derived wet gas accompanied by oil, and it is typically generated by type III kerogen of mudstones in coal measures of the Wuyun Formation. Family III is mixed-type wet gas whose primary compound is oil-associated gas, and it is mainly generated by type II kerogen in the Xinancun Formation and partly from type III kerogen in the Wuyun Formation in the Daluomi (DLM) Uplift. The family I and II hydrocarbon gases are located in the Zhuozhugang (ZSG) Sag. Family III hydrocarbon gas was formed in the mixing process of different genesis gas through the active faults because the late Miocene transpressional strength of uplift in the DLM Uplift was more intense than that in the ZSG Sag after the development of increased accommodation space coeval with intrabasinal rifting before Oligocene.

Non-hydrocarbons of significance in petroleum exploration: volatile fatty acids and non-hydrocarbon gases

1987 ◽  
Vol 51 (362) ◽  
pp. 483-493 ◽  
Author(s):  
G. P. Cooles ◽  
A. S. Mackenzie ◽  
R. J. Parkes
Keyword(s):  
Volatile Fatty Acids ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Gas Generation ◽  
Hydrocarbon Gases ◽  
Natural Systems ◽  
Gaseous Products ◽  
Hydrous Pyrolysis ◽  
Hydrocarbon Gas ◽  
Thermodynamic Effects

AbstractNon-hydrocarbon gas species (CO2, N2, H2) are locally important in exploration for gas, and there is a growing body of evidence that acid water originating in shales materially affects the diagenesis of nearby sandstones. These gases have been studied by analysing the products of closed-vessel hydrous pyrolysis of known petroleum source rocks, and comparing the results with field observations. Alteration of petroleum source rocks at temperatures >250°C yields a significant amount of non-hydrocarbon components. Ethanoate and higher acid anions are liberated in substantial quantities; the yield appears to be related to the oxygen content of the sedimentary organic matter present.The non-hydrocarbon gases CO2, H2and N2are frequently the dominant gaseous products from hydrous pyrolysis: in the natural environment the same rock sequences at a higher maturity preferentially generate hydrocarbon gases—mainly methane. This discrepancy may be attributed to reaction and phase thermodynamic effects between laboratory and natural systems, behaviour that has important implications in the prediction of gas generation and composition in nature by source rock pyrolysis in the laboratory.

Petroleum geology of the 2018 offshore acreage release areas

2018 ◽  
Vol 58 (2) ◽  
pp. 437
Author(s):  
Thomas Bernecker ◽  
George Bernardel ◽  
Claire Orlov ◽  
Nadège Rollet
Keyword(s):  
Information Management System ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Data Repository ◽  
North West ◽  
Work Program ◽  
Petroleum Systems ◽  
The North ◽  
Well Data ◽  
Offshore Petroleum

A total of 21 areas were released in 2018 for offshore petroleum exploration. They are located in the Bonaparte, Browse, Northern Carnarvon, Bight, Otway and Gippsland basins. All release areas were supported by industry nominations, indicating that interest in exploring Australia’s offshore basins remains strong, despite the significant decrease in the number of exploration wells drilled in recent years. Sixteen areas are being released under the work program bidding system with two rounds, one closing on 18 October 2018 and the other on 21 March 2019. Five areas are being released for cash bidding and include the producible La Bella gas accumulation in the Otway Basin. Prequalification for participation in the cash-bid auction closes on 4 October 2018 with the auction scheduled for 7 February 2019. Geoscience Australia continues to support industry activities by acquiring, interpreting and integrating pre-competitive datasets that are made freely available as part of the agency’s regional petroleum geological studies. The regional evaluation of the petroleum systems in the Browse Basin has been completed and work continues on assessing the distribution of Early Triassic source rocks and related petroleum occurrences across the North West Shelf. A wealth of seismic and well data, submitted under the Offshore Petroleum and Greenhouse Gas Storage Act 2006, are made available through the National Offshore Petroleum Information Management System. Additional datasets are accessible through Geoscience Australia’s data repository.

Burial History Reconstruction of the Appalachian Basin in Kentucky, West Virginia, Pennsylvania, and New York, Using 1D Petroleum System Models

2019 ◽  
Vol 56 (4) ◽  
pp. 365-396
Author(s):  
Debra Higley ◽  
Catherine Enomoto
Keyword(s):  
New York ◽  
Vitrinite Reflectance ◽  
Structural Complexity ◽  
Appalachian Basin ◽  
Source Rocks ◽  
Burial History ◽  
Gas Generation ◽  
Deep Basin ◽  
Utica Shale ◽  
Wet Gas

Nine 1D burial history models were built across the Appalachian basin to reconstruct the burial, erosional, and thermal maturation histories of contained petroleum source rocks. Models were calibrated to measured downhole temperatures, and to vitrinite reflectance (% Ro) data for Devonian through Pennsylvanian source rocks. The highest levels of thermal maturity in petroleum source rocks are within and proximal to the Rome trough in the deep basin, which are also within the confluence of increased structural complexity and associated faulting, overpressured Devonian shales, and thick intervals of salt in the underlying Silurian Salina Group. Models incorporate minor erosion from 260 to 140 million years ago (Ma) that allows for extended burial and heating of underlying strata. Two modeled times of increased erosion, from 140 to 90 Ma and 23 to 5.3 Ma, are followed by lesser erosion from 5.3 Ma to Present. Absent strata are mainly Permian shales and sandstone; thickness of these removed layers increased from about 6200 ft (1890 m) west of the Rome trough to as much as 9650 ft (2940 m) within the trough. The onset of oil generation based on 0.6% Ro ranges from 387 to 306 Ma for the Utica Shale, and 359 to 282 Ma for Middle Devonian to basal Mississippian shales. The ~1.2% Ro onset of wet gas generation ranges from 360 to 281 Ma in the Utica Shale, and 298 to 150 Ma for Devonian to lowermost Mississippian shales.

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