BASEMENT CONTROL ON THE DEVELOPMENT OF EXTENSIONAL SYSTEMS IN AUSTRALIA'S TIMOR SEA: AN EXAMPLE OF HYBRID HARD LINKED/SOFT LINKED FAULTING?

1996 ◽  
Vol 36 (1) ◽  
pp. 161 ◽  
Author(s):  
G.W. O'Brien ◽  
R. Higgins ◽  
P. Symonds ◽  
P. Quaife ◽  
J. Colwell ◽  
...  
Keyword(s):  
Seismic Data ◽  
Source Rocks ◽  
Aeromagnetic Data ◽  
Predictive Tool ◽  
Fault Type ◽  
Fracture Systems ◽  
Transport Direction ◽  
First Pass ◽  
Timor Sea ◽  
Migration Pathways

A series of rift models has been developed for basin systems in Australia's Timor Sea, via the interpretation of newly acquired deep crustal seismic and high resolution aeromagnetic data. These models, which incorporate observations on rift architecture, fault geometries, fault orientation, basement grain and composition, extensional transport direction and reactivation history, have then been iteratively tested by sophisticated analogue modelling experiments. This work has led to the development of a hybrid hard linked/soft linked (basement-involved/basement-detached) fault model. In this model, basement grain is the principal control on the rift architecture that develops, with pre-existing fracture systems acting to establish discrete offsets (hard linkages) between adjacent extensional faults. It is these basement features that produce the recti-linear features which are so common in aeromagnetic data around the Australian margin. With progressively greater extension, the basement-involved, hard linked system exerts no through-going (transfer fault-type) influence over the faulting within the overlying syn-rift phase, with the linkages between the syn-rift faults being 'soft' (via relay ramps, etc). However, as the hard links do act to relay the extensional faults or to flip their polarity (thereby typically producing cross-basinal highs), hard links strongly segment the extensional system into compartments of similar extensional style, and do control the relative positions of source rocks, fluid migration pathways and reservoirs within the rift. During basin reactivation (particularly inversion), the location and geometry of the underpinning, hard linked basement features closely control the locations of the traps that develop in the syn-and post-rift section, and the late-stage fluid flow history. When combined with aeromagnetic data, which define the location of the under-pinning, recti-linear, hard linked basement features, and some regional seismic data, these observations provide a first-pass predictive tool for determining where source depocentres, reservoirs and major structures are likely to be developed in a frontier basin, or where more subtle structural and/or stratigraphic traps might be found in a mature province.

HYDROCARBON-RELATED DIAGENETIC ZONES (HRDZs) IN THE VULCAN SUB-BASIN, TIMOR SEA: RECOGNITION AND EXPLORATION IMPLICATIONS

1995 ◽  
Vol 35 (1) ◽  
pp. 220 ◽  
Author(s):  
G.W. O'Brien ◽  
E.P. Woods
Keyword(s):  
Late Miocene ◽  
Predictive Tool ◽  
Hydrocarbon Migration ◽  
Areal Distribution ◽  
Carbon Isotopic ◽  
Individual Structure ◽  
History Of ◽  
Timor Sea ◽  
Two Stages ◽  
Migration Pathways

Within very localised areas of the Vulcan Subbasin, the Eocene Grebe Formation sandstones are strongly cemented with carbonate. These cemented sands are recognisable on seismic data as zones of anomalously high velocity, and result in both time 'pull-up' and deterioration of the stack response in the underlying section.To determine the nature and origin of these cemented zones, their isotopic, mineralogical and petrologic compositions have been characterised, their seismic response and areal distribution established, and these observations integrated with ~2,730 km of AGSO water column geochemical ('sniffer-type') data.The carbon isotopic compositions of the carbonate within the cemented Grebe sands are diagnostic of carbonates formed principally via the oxidation of migrating, thermogenic hydrocarbons. Oxidation of the hydrocarbons took place in two stages: an earlier phase led to calcite precipitation, whereas a later phase produced (generally subsidiary) ferroan dolomite/ankerite cementation.Areas of known, present-day hydrocarbon seepage from the seafloor, such as over major faults on the Skua Horst and along the Vulcan Sub-basin/ Londonderry High boundary zone, are invariably associated with zones of highly cemented Eocene sands. Similarly, areas of known Tertiary hydrocarbon seepage, such as those associated with the residual oil columns on the Eider Horst, also contain strongly cemented Eocene sandstones.These observations have established a causal relationship between the presence of these Hydrocarbon-Related Diagenetic Zones (or HRDZs) in the Eocene sandstones and Tertiary-Quaternary hydrocarbon seepage. It is likely that most of the cementation occurred during the Late Miocene/Early Pliocene, when the Grebe Formation sands were at a shallow depth of burial(Recognition of this causal association has allowed several insights to be gained into the exploration potential and reactivation history of structures within the Vulcan Sub-basin. Mapping of the areal distribution of the cemented zones can effectively define hydrocarbon migration pathways. More importantly, however, predictable relationships exist between the seismic expression of the HRDZs, the total amount of hydrocarbons that have leaked from the traps, and the obliquity between the Jurassic and Late Miocene fault trends over the respective structures. A continuum exists between highintegrity accumulations, in which the fault trends are parallel and the HRDZs are small or absent, and breached accumulations, in which a significant obliquity exists between the respective fault trends and the HRDZs are large and seismically-intense.These observations provide a potential predictive tool for evaluating undrilled structures. It may be possible to determine, from the integration of seismic structural mapping and the characterisation of the seismic expression of the HRDZs, not only whether an individual structure is ever likely to have had a hydrocarbon column, but whether that column is likely to be preserved.

PETROLEUM PLAY ELEMENT PREDICTION FOR THE CRETACEOUS-TERTIARY BASIN PHASE, NORTHERN CARNARVON BASIN

1997 ◽  
Vol 37 (1) ◽  
pp. 315 ◽  
Author(s):  
K. K. Romine ◽  
J. M. Durrant ◽  
D. L. Cathro ◽  
G. Bernardel
Keyword(s):  
Focal Point ◽  
Source Rocks ◽  
Predictive Tool ◽  
Petroleum Systems ◽  
The North ◽  
Northern Carnarvon Basin ◽  
And Migration ◽  
Play Elements ◽  
Migration Pathways ◽  
Carnarvon Basin

A regional tectono-stratigraphic framework has been developed for the Cretaceous and Tertiary section in the Northern Carnarvon Basin. This framework places traditional observations in a new context and provides a predictive tool for determining the temporal occurrence and spatial distribution of the lithofacies play elements, that iss reservoir, source and seal.Two new, potential petroleum systems have been identified within the Barremian Muderong Shale and Albian Gearle Siltstone. These potential source rocks could be mature or maturing along a trend that parallels the Alpha Arch and Rankin Platform, and within the Exinouth Sub-basin.A favourable combination of reservoir and seal can be predicted for the early regressive part of the Creta- ceous-Tertiary basin phase (Campanian-Palaeocene). Lowstand and transgressive (within incised valleys) reservoirs are more likely to be isolated and encased in sealing shales, similar to lowstand reservoir facies deposited during the transgressive part of the basin phase, for example, the M. australis sand play.The basin analysis revealed the important role played by pre-existing Proterozoic-Palaeozoic lineaments during extension, and the subsequent impact on play elements, in particular, the distribution of reservoir, fluid migration, and trap development. During extension, the north-trending lineaments influenced the compart mentalisation of the Northern Carnarvon Basin into discrete depocentres. Relay ramp-style accommodation zones developed, linking the sub-basins, and acting as pathways for sediment input into the depocentres and, later in the basin's history, as probable hydrocarbon migration pathways. The relay accommodation zones are a dynamic part of the basin architecture, acting as a focal point for response to intraplate stresses and the creation, modification and destruction of traps and migration pathways.

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.

A possible new hydrocarbon play, offshore central West Greenland

1998 ◽  
pp. 28-30
Author(s):  
Nina Skaarup ◽  
James A. Chalmers
Keyword(s):  
Seismic Data ◽  
Mineral Resources ◽  
Source Rocks ◽  
Bright Spot ◽  
Offshore Area ◽  
West Greenland ◽  
The Government ◽  
Structural Closure ◽  
Multichannel Seismic Data ◽  
Seismic Lines

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Skaarup, N., & Chalmers, J. A. (1998). A possible new hydrocarbon play, offshore central West Greenland. Geology of Greenland Survey Bulletin, 180, 28-30. https://doi.org/10.34194/ggub.v180.5082 _______________ The discovery of extensive seeps of crude oil onshore central West Greenland (Christiansen et al. 1992, 1994, 1995, 1996, 1997, 1998, this volume; Christiansen 1993) means that the central West Greenland area is now prospective for hydrocarbons in its own right. Analysis of the oils (Bojesen-Koefoed et al. in press) shows that their source rocks are probably nearby and, because the oils are found within the Lower Tertiary basalts, the source rocks must be below the basalts. It is therefore possible that in the offshore area oil could have migrated through the basalts and be trapped in overlying sediments. In the offshore area to the west of Disko and Nuussuaq (Fig. 1), Whittaker (1995, 1996) interpreted a few multichannel seismic lines acquired in 1990, together with some seismic data acquired by industry in the 1970s. He described a number of large rotated fault-blocks containing structural closures at top basalt level that could indicate leads capable of trapping hydrocarbons. In order to investigate Whittaker’s (1995, 1996) interpretation, in 1995 the Geological Survey of Greenland acquired 1960 km new multichannel seismic data (Fig. 1) using funds provided by the Government of Greenland, Minerals Office (now Bureau of Minerals and Petroleum) and the Danish State through the Mineral Resources Administration for Greenland. The data were acquired using the Danish Naval vessel Thetis which had been adapted to accommodate seismic equipment. The data acquired in 1995 have been integrated with the older data and an interpretation has been carried out of the structure of the top basalt reflection. This work shows a fault pattern in general agreement with that of Whittaker (1995, 1996), although there are differences in detail. In particular the largest structural closure reported by Whittaker (1995) has not been confirmed. Furthermore, one of Whittaker’s (1995) smaller leads seems to be larger than he had interpreted and may be associated with a DHI (direct hydrocarbon indicator) in the form of a ‘bright spot’.

scholarly journals Can hydrocarbon source rocks be identified on seismic data?

Geology ◽  
2011 ◽  
Vol 39 (12) ◽  
pp. 1167-1170 ◽  
Author(s):  
Helge Løseth ◽  
Lars Wensaas ◽  
Marita Gading ◽  
Kenneth Duffaut ◽  
Michael Springer
Keyword(s):  
Seismic Data ◽  
Source Rocks ◽  
Hydrocarbon Source Rocks

TECTONOSTRATIGRAPHY AND POTENTIAL SOURCE ROCKS OF THE BASS BASIN

2005 ◽  
Vol 45 (1) ◽  
pp. 601 ◽  
Author(s):  
J.E. Blevin ◽  
K.R. Trigg ◽  
A.D. Partridge ◽  
C.J. Boreham ◽  
S.C. Lang
Keyword(s):  
Seismic Data ◽  
Middle Eocene ◽  
Liquid Hydrocarbon ◽  
Source Rocks ◽  
Rift System ◽  
Complex Nature ◽  
Hydrocarbon Generation ◽  
Crustal Extension ◽  
Principal Source ◽  
Seismic Sequence Stratigraphy

A study of the Bass Basin using a basin-wide integration of seismic data, well logs, biostratigraphy and seismic/sequence stratigraphy has resulted in the identification of six basin phases and related megasequences/ supersequences. These sequences correlate to three periods of extension and three subsidence phases. The complex nature of facies relationships across the basin is attributed to the mostly terrestrial setting of the basin until the Middle Eocene, multiple phases of extension, strong compartmentalisation of the basin due to underlying basement fabric, and differential subsidence during extension and early subsidence phases. The Bass Basin formed through upper crustal extension associated with three main regional events:rifting in the Southern Margin Rift System;rifting associated with the formation of the Tasman Basin; and,prolonged separation, fragmentation and clearance between the Australian and Antarctic plates along the western margin of Tasmania.The final stage of extension was the result of far-field stresses that were likely to be oblique in orientation. The late Early Eocene to Middle Eocene was a time of rifttransition and early subsidence as the effects of intra-plate stresses progressively waned from east to west. Most of the coaly source rocks now typed to liquid hydrocarbon generation were deposited during this rift-transition phase. Biostratigraphic studies have identified three major lacustrine episodes during the Late Cretaceous to Middle Eocene. The lacustrine shales are likely to be more important as seal facies, while coals deposited fringing the lakes are the principal source rocks in the basin.

NEW PETROLEUM MODELS IN THE PEDIRKA BASIN, NORTHERN TERRITORY, AUSTRALIA

2002 ◽  
Vol 42 (1) ◽  
pp. 259 ◽  
Author(s):  
G.J. Ambrose ◽  
K. Liu ◽  
I. Deighton ◽  
P.J. Eadington ◽  
C.J. Boreham
Keyword(s):  
Oil And Gas ◽  
South Australia ◽  
Sedimentary Basins ◽  
Poor Quality ◽  
Northern Territory ◽  
Early Jurassic ◽  
Source Rocks ◽  
Late Triassic ◽  
Hydrocarbon Expulsion ◽  
Migration Pathways

The northern Pedirka Basin in the Northern Territory is sparsely explored compared with its southern counterpart in South Australia. Only seven wells and 2,500 km of seismic data occur over a prospective area of 73,000 km2 which comprises three stacked sedimentary basins of Palaeozoic to Mesozoic age. In this area three petroleum systems have potential related to important source intervals in the Early Jurassic Eromanga Basin (Poolowanna Formation), the Triassic Simpson Basin (Peera Peera Formation) and Early Permian Pedirka Basin (Purni Formation). They are variably developed in three prospective depocentres, the Eringa Trough, the Madigan Trough and the northern Poolowanna Trough. Basin modelling using modern techniques indicate oil and gas expulsion responded to increasing early Late Cretaceous temperatures in part due to sediment loading (Winton Formation). Using a composite kinetic model, oil and gas expulsion from coal rich source rocks were largely coincident at this time, when source rocks entered the wet gas maturation window.The Purni Formation coals provide the richest source rocks and equate to the lower Patchawarra Formation in the Cooper Basin. Widespread well intersections indicate that glacial outwash sandstones at the base of the Purni Formation, herein referred to as the Tirrawarra Sandstone equivalent, have regional extent and are an important exploration target as well as providing a direct correlation with the prolific Patchawarra/Tirrawarra petroleum system found in the Cooper Basin.An integrated investigation into the hydrocarbon charge and migration history of Colson–1 was carried out using CSIRO Petroleum’s OMI (Oil Migration Intervals), QGF (Quantitative Grain Fluorescence) and GOI (Grains with Oil Inclusions) technologies. In the Early Jurassic Poolowanna Formation between 1984 and 2054 mRT, elevated QGF intensities, evidence of oil inclusions and abundant fluorescing material trapped in quartz grains and low displacement pressure measurements collectively indicate the presence of palaeo-oil and gas accumulation over this 70 m interval. This is consistent with the current oil show indications such as staining, cut fluorescence, mud gas and surface solvent extraction within this reservoir interval. Multiple hydrocarbon migration pathways are also indicated in sandstones of the lower Algebuckina Sandstone, basal Poolowanna Formation and Tirrawarra Sandstone equivalent. This is a significant upgrade in hydrocarbon prospectivity, given previous perceptions of relatively poor quality and largely immature source rocks in the Basin.Conventional structural targets are numerous, but the timing of hydrocarbon expulsion dictates that those with an older drape and compaction component will be more prospective than those dominated by Tertiary reactivation which may have resulted in remigration or leakage. Preference should also apply to those structures adjacent to generative source kitchens on relatively short migration pathways. Early formed stratigraphic traps at the level of the Tirrawarra Sandstone equivalent and Poolowanna Formation are also attractive targets. Cyclic sedimentation in the Poolowanna Formation results in two upward fining cycles which compartmentalise the sequence into two reservoir–seal configurations. Basal fluvial sandstone reservoirs grade upwards into topset shale/coal lithologies which form effective semi-regional seals. Onlap of the basal cycle onto the Late Triassic unconformity offers opportunities for stratigraphic entrapment.

THE EVOLUTION OF THE BERNIER RIDGE, SOUTHERN CARNARVON BASIN, WESTERN AUSTRALIA:IMPLICATIONS FOR PETROLEUM PROSPECTIVITY

2004 ◽  
Vol 44 (1) ◽  
pp. 241 ◽  
Author(s):  
A.M. Lockwood ◽  
C. D’Ercole
Keyword(s):  
Seismic Data ◽  
Large Scale ◽  
Sedimentary Basins ◽  
Early Carboniferous ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Large Igneous Province ◽  
Satellite Gravity ◽  
Tectonic Events ◽  
Carnarvon Basin

The basement topography of the Gascoyne Platform and adjoining areas in the Southern Carnarvon Basin was investigated using satellite gravity and seismic data, assisted by a depth to crystalline basement map derived from modelling the isostatic residual gravity anomaly. The resulting enhanced view of the basement topography reveals that the Gascoyne Platform extends further westward than previously indicated, and is bounded by a northerly trending ridge of shallow basement, named the Bernier Ridge.The Bernier Ridge is a product of rift-flank uplift prior to the Valanginian breakup of Gondwana, and lies east of a series of small Mesozoic syn-rift sedimentary basins. Extensive magmatic underplating of the continental margin associated with this event, and a large igneous province is inferred west of the ridge from potential field and seismic data. Significant tectonic events that contributed to the present form of the Bernier Ridge include the creation of the basement material during the Proterozoic assembly of Rodinia, large-scale faulting during the ?Cambrian, uplift and associated glaciation during the early Carboniferous, and rifting of Gondwana during the Late Jurassic. The depositional history and maturity of the Gascoyne Platform and Bernier Ridge show that these terrains have been structurally elevated since the mid-Carboniferous.No wells have been drilled on the Bernier Ridge. The main source rocks within the sedimentary basins west of the Bernier Ridge are probably Jurassic, similar to those in the better-known Abrolhos–Houtman and Exmouth Sub-basins, where they are mostly early mature to mature and within the oil window respectively. Within the Bernier Ridge area, prospective plays for petroleum exploration in the Jurassic succession include truncation at the breakup unconformity sealed by post-breakup shale, and tilted fault blocks sealed by intraformational shale. Plays in the post-breakup succession include stratigraphic traps and minor rollover structures.

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