A re-evaluation of the Lower to Middle Triassic on the Candace Terrace, Northern Carnarvon Basin

2017 ◽  
Vol 57 (1) ◽  
pp. 263 ◽  
Author(s):  
Roisin McGee ◽  
Jeff Goodall ◽  
Stephen Molyneux

The Lower to Middle Triassic mixed carbonate–clastic system in the Northern Carnarvon Basin is poorly understood relative to the stratigraphically younger Jurassic play systems. Few well penetrations and a lack of quality seismic data have deterred exploration of this interval for many years. In recent times, the Lower to Middle Triassic source potential has been comprehensively de-risked within the Roebuck Basin, with subsequent implications across the entire North West Shelf of Australia, opening up the possibility of an entirely new regional play fairway. This paper focuses on the Candace Terrace, on the southern flank of the Carnarvon Basin, where seismic observations and interpretations of Lower to Middle Triassic submarine canyon systems have been made. The stratigraphic elements of this play interval can now be more clearly observed with the aid of 3D seismic data. Amplitude extractions show the internal geometries of these highly erosive systems are sinuous, compensating flows. The aims of this paper are to postulate the stratigraphy of the Lower to Middle Triassic on the Candace Terrace, highlight the tectonic cause of the canyon systems and discuss the prospectivity of the observed turbidite features.

2002 ◽  
Vol 42 (1) ◽  
pp. 287 ◽  
Author(s):  
L.L. Pryer ◽  
K.K. Romine ◽  
T.S. Loutit ◽  
R.G. Barnes

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.


2019 ◽  
Vol 59 (2) ◽  
pp. 851
Author(s):  
Roman Beloborodov ◽  
Marina Pervukhina ◽  
Valeriya Shulakova ◽  
Dimitri Chagalov ◽  
Matthew Josh ◽  
...  

Predicting the mineralogical composition of shales is crucial for drilling operations related to hydrocarbon exploration/production as well as for the assessment of their sealing capacity as hydrocarbon or CO2 barriers. For example, hydrocarbon exploration in the Northern Carnarvon Basin, North-West Shelf, Australia is hindered by the presence of a thick (up to 1 km) smectite-rich shale seal that spreads regionally. Complex structures of the channelised oil and gas fields in the area make it necessary to drill deviated wells through that seal. The maximum deviation angle at which successful drilling is possible depends strongly on the clay mineralogy and, in particular, on the smectite content in the shale. Here, we introduce a novel workflow combining seismic data, well logs and laboratory measurements to infer shale composition at the reservoir scale. It is applied to the Duyfken 3D seismic survey in the central part of the Northern Carnarvon Basin. Interpretation results are verified against the laboratory X-ray diffraction measurements from the test well that was not used for the interpretation. The results match the test data well within the determined uncertainty bounds.


2021 ◽  
Author(s):  
Chris Elders ◽  
Sara Moron

<p>The North West Shelf of Australia has experienced numerous rift events during its prolonged evolution that most likely started in the Lower Palaeozoic and continued through to the formation of the present day passive margin in the Lower Cretaceous.  Carboniferous and Permian is associated with rifting of the Lhasa terrane, a phase extension in the Lower and Middle Jurassic associated with the separation of the Argo terrane Upper Jurassic to Lower Cretaceous extension culminated in the separation of Greater India and Australia.  Investigations based on interpretation of extensive, public domain seismic data, combined with numerical mechanical modelling, demonstrate that crustal structure, rheology and structural fabrics inherited from older events exert a significant control on the architecture of younger rifts.</p><p>Defining the older, more deeply buried rift episodes is challenging, but with seismic data that now images deeper structures more effectively, it is clear that NE-SW oriented Carboniferous to Permian aged rift structures control the overall geometry of the margin.  Variations in the timing, distribution and intensity of that rift may account for some of the complexity that governs the Triassic – a failed arm of the rift system might account for the accumulation of thick sequences of fluvio-delatic sediments in an apparent post-rift setting, while active deformation and igneous activity continued elsewhere on the margin.</p><p>A renewed phase of extension began in the latest Triassic in the western part of the Northern Carnarvon Basin, but became progressively younger to the NE.  High-resolution mechanical numerical experiments show that the dual mode of extension that characterises the Northern Carnarvon Basin, where both distributed and localised deformation occurs at the same time, is best explained by necking and boudinage of strong lower crust, inherited form the Permian rift event, proximal to the continental margin, and a subdued extensional strain rate across the distal extended margin.  A very clear and consistent pattern of ENE oriented extension, which interacts obliquely with the older NE-SW oriented Permian aged structures, is apparent across the whole of the Northern Carnarvon Basin and extends north east into the Roebuck and Browse Basins.  This is at odds with the NW-SE oriented extension predicted by the separation of the Argo terrane which occurs at this time.  This may be explained by the detached style of deformation that characterises the Mesozoic interval.  Alternatively, the separation of Greater India may have exerted a stronger influence on the evolution of the margin during the Jurassic than hitherto recognised.</p>


2018 ◽  
Vol 58 (2) ◽  
pp. 839 ◽  
Author(s):  
Jon Minken ◽  
Melissa Thompson ◽  
Jack Woodward ◽  
Fred Fernandes ◽  
Rylan Fabrici

Recent drilling activity and new seismic data have contributed to the understanding of the Lower Keraudren Formation in the Bedout Sub-Basin. The Lower Keraudren Formation is a thick (>5 km) succession of strata that was deposited rapidly during the Anisian of the Middle Triassic. Distinctive characteristics related to sediment provenance, sediment supply and accommodation have facilitated subdivision of the Formation into eight informal units: the Milne, Crespin, Baxter, Caley, Hove, Barret, Palma, and Huxley members. Tectonic elements of the East Gondwana Interior Rift and the Bedout High influenced the Sub-basin geometry during deposition of the Lower Keraudren. Extensional tectonics of the East Gondwana Interior Rift generated a series of Palaeozoic tilted fault blocks and grabens, which influenced the stratigraphic architecture, sediment dispersal patterns and distribution of reservoir and source rock facies. The structurally proud Bedout High, a roughly circular (~60 km wide) igneous feature, created a northern boundary to deposition. Seismic stratigraphic interpretation has characterised the interval as a series of north west prograding wedges. Well based data indicates the section is dominated by fluvio-deltaic deposits. Separating the Caley and Hove Members is a significant unconformity that is associated with renewed uplift of the Bedout High and a change in sediment provenance. Chemostratigraphy and petrology indicates the Caley and older strata were derived from a more mature sediment source, whereas the Hove and younger a more immature metamorphic source. Distinct changes in reservoir quality are observed above and below the Caley–Hove unconformity. Below the unconformity, the older, more mature sandstones exhibit superior reservoir quality compared with the younger, more immature sandstones.


2015 ◽  
Vol 55 (2) ◽  
pp. 492
Author(s):  
Howard Ewan ◽  
Frances Cullen

Since peaking at more than 200 MMbbl in 2000, offshore oil production in Australia has declined steadily by falling to below 100 MMbbl in 2011. Various initiatives and policies have been introduced by the Australian Government to encourage exploration of frontier basins to find a new oil province that may stop this production decline. By analysing the exploration and production profiles of established petroleum provinces in offshore Australia, the reasons behind similarities, differences and trends can be understood. This knowledge can be applied to future exploration efforts and provides a variety of possible outcomes should success come in immature and frontier provinces. Analysis of data mainly from the Bonaparte, Browse, Gippsland, North Carnarvon and, to a lesser extent, the Otway and Perth basins, shows that early success typifies these petroleum provinces. The degree of early success is, however, not always a good indication of later exploration results. While the creaming curves of some basins conform to the hypothetical basin creaming curve, characterised by large initial reserves increases and falling discovery size across time, it is evident that this cannot be universally applied. Considerable success much later in the exploration history of a basin is demonstrated, by success driven policy implementation, exploration incentivisation and increases in data acquisition. In this extended abstract, the importance of using advances in technology is demonstrated by reserves additions following the opening up of deepwater areas and the increased use of high-density 2D seismic and 3D seismic data. This information supports the notion that frontier areas may hold the key to alleviating dependence on foreign supply, success in immature basins is still possible and should not be overlooked.


2021 ◽  
Vol 61 (2) ◽  
pp. 600
Author(s):  
Michael Curtis ◽  
Simon Holford ◽  
Mark Bunch ◽  
Nick Schofield

The Northern Carnarvon Basin (NCB) forms part of the North West Australian margin. This ‘volcanic’ rifted margin formed as Greater India rifted from the Australian continent through the Jurassic, culminating in breakup in the Early Cretaceous. Late Jurassic to Early Cretaceous syn-rift intrusive magmatism spans 45000km2 of the western Exmouth Plateau and the Exmouth Sub-basin; however, there is little evidence of associated contemporaneous volcanic activity, with isolated late Jurassic volcanic centres present in the central Exmouth Sub-basin. The scarcity of observed volcanic centres is not typical of the extrusive components expected in such igneous provinces, where intrusive:extrusive ratios are typically 2–3:1. To address this, we have investigated the processes that led to the preservation of a volcanic centre near the Pyrenees field and the Toro Volcanic Centre (TVC). The volcanic centre near the Pyrenees field appears to have been preserved from erosion associated with the basin-wide KV unconformity by fault-related downthrow. However, the TVC, which was also affected by faulting, is located closer to the focus of regional early Cretaceous uplift along the Ningaloo Arch to the south and was partly eroded. With erosion of up to 2.6km estimated across the Ningaloo Arch, which, in places, removed all Jurassic strata, we propose that the ‘Exmouth Volcanic Province’ was originally much larger, extending south from the TVC into the southern Exmouth Sub-basin prior to regional uplift and erosion, accounting for the ‘missing’ volume of extrusive igneous material in the NCB.


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