petroleum
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Chiefly charts and maps, includes explanatory notes
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Legacy product - no abstract available
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The Beagle Sub-basin is a Mesozoic rift basin in the Northern Carnarvon Basin. Oil discovered at Nebo-1 highlights an active petroleum system. 3D seismic interpretation identified pre, syn and post-rift megasequences. Pre-rift fluvio-deltaic and marine sediments were deposited during a thermal sag phase of the Westralian Super Basin. Low rates of extension (Rhaetian to Oxfordian) deposited fluvio-deltaic and marine sediments. During early post-rift thermal subsidence, sediments onlapped and eroded tilted fault blocks formed during the syn-rift phase. Consequently the regional seal (Early Cretaceous Muderong Shale) is absent in the centre. Subsequent successions are dominated by a prograding carbonate wedge showing evidence of erosion from tectonic and eustatic sea level change. 1D burial history modeling of Nebo-1 and Manaslu-1 show that all source rocks are currently at their maximum depths of burial. Sediments to the Late Cretaceous are in the early maturity window for both wells. The Middle Jurassic Legendre Formation reaches mid maturity in Nebo-1. Source, reservoir and seals are present throughout the Triassic to earliest Cretaceous, however, the absence of the regional seal in the central sub-basin reduces exploration targets. The lack of significant inversion increases the likelihood of maintaining trap integrity. Potential plays include compaction folds over tilted horst blocks, roll over and possible inversion anticlines, basin floor fans and intra-formational traps within fluvio-deltaic deposits. Late Cretaceous and younger sediments are unlikely to host significant hydrocarbons due to lack of migration pathways. Source rocks are of adequate maturity and deep faults act as pathways for hydrocarbon migration.
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Petroleum tenement (titles) map, key and list of operating companies in Australia at 30th June, 1965
Legacy product - no abstract available
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Legacy product - no abstract available
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Legacy product - no abstract available
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Legacy product - no abstract available
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Legacy product - no abstract available
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Legacy product - no abstract available
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Cliff Head is the only producing oil field in the offshore Perth Basin. The lack of other exploration success has lead to a perception that the primary source rock onshore (Triassic Kockatea Shale) is absent or has limited generative potential. However, recent offshore well studies show the unit is present and oil prone. Multiple palaeo-oil columns were identified within Permian reservoir below the Kockatea Shale regional seal. This prompted a trap integrity study into fault reactivation as a critical risk for hydrocarbon preservation. Breach of accumulations could be attributed to mid Jurassic extension, Valanginian breakup, margin tilt or Miocene structuring. The study focused on four prospects, covered by 3D seismic data, containing breached and preserved oil columns. 3D geomechanical modelling simulated the response of trap-bounding faults and fluid flow to mid Jurassic-Early Cretaceous NW-SE extension. Calibration of modelling results against fluid inclusion data, as well as current and palaeo-oil columns, demonstrates that along-fault fluid flow correlates with areas of high shear and volumetric strains. Localisation of deformation leads to both an increase in structural permeability promoting fluid flow, and the development of hard-linkages between reactivated Permian reservoir faults and Jurassic faults producing top seal bypass. The main structural factors controlling the distribution of permeable fault segments are: (i) failure for fault strikes 350??110?N; (ii) fault plane intersections generating high shear deformation and dilation; and (iii) preferential reactivation of larger faults shielding neighbouring structures. These results point to a regional predictive approach for assessing trap integrity in the offshore Perth Basin.