Legacy product - no abstract available

Legacy product - no abstract available

B.M.R. Maclean No. 1 was a fully cored stratigraphic hole drilled on the eastern margin of the Clarence-Moreton Basin near Evans Head. It reached a total depth of 664.8 m and intersected 590.05 m of Marburg Formation overlying 74.75 m of Ripley Road Sandstone. The lower 42.60 m of the Marburg Formation correlates with the Calamia Member recognised by Etheridge & others (1985). The sequence is mostly multistorey fluvial channel sandstone with only a small proportion of fine grained facies so that potential hydrocarbon source rocks are rare. Porous sandstone is also rare, though parts of the Calamia Member and the Ripley Road Sandstone may be porous and permeable.

Exploration in the offshore northern Carnarvon Basin during the last two decades has resulted in a number of major oil and gas discoveries. Recent discoveries in the Dampier (di Toro, 1994; Delfos, 1994), Exmouth (Bauer et al., 1994; Lawry & Carter, 1994; Mitchelmore & Smith, 1994) and Barrow (Beacher et al., 1994; Sit et al., 1994) sub-basins ensure that exploration activity is likely to remain high in these areas for the near future. However, some of these discoveries have been small fields or individual wells with residual oil columns, indicating that still greater quantities of hydrocarbons have escaped from the traps. Recent work on oil-filled fluid inclusions (Lisk & Eadington, 1994) indicates that the loss of hydrocarbons from pre-Cretaceous reservoirs and traps occurred during the past 20 million years, beginning in the Miocene. These hydrocarbons may have been lost, but could potentially have been trapped in younger Cretaceous and Tertiary reservoirs. The Carnarvon Cretaceousflertiary Tie study proposes to address this issue by collecting and interpreting a regional high-resolution seismic survey, within the broad structural and tectonic framework provided by the Continental Margins Program Northwest Shelf Project. The main objectives are: 1) construction of a regional, sequence-based chronostratigraphic framework for the Cretaceous and Tertiary within which the occurrence and distribution of potential seal and reservoir facies may be analyzed and predicted; 2) assessment of the post-Valanginian fault reactivation history of the northern Carnarvon Basin and the implications for: (a) the migration of hydrocarbons from pre-Cretaceous traps and (b) the integrity of potential Cretaceous and Tertiary seals; 3) determination of the probability of secondary migration and entrapment of hydrocarbons within Cretaceous and Tertiary strata. Approximately 4240 krn of high-resolution seismic data has been proposed for acquisition by AGSO's RV Rig Seismic. The data set will comprise 23 seismic lines tying 107 wells in the Exrnouth, Barrow, Dampier and Beagle Sub-basins. These data will tie with and complement the deep-seismic grid previously acquired by AGSO in the Carnarvon Basin. The seismic survey will be acquired using the latest high-resolution seismic technology. Data will be recorded using bubble-free GI air guns and with the following parameters: 3000m streamer; 12.5m group interval, 18.75m shot interval, recording frequency bandwidth of 4- 180Hz; 2ms sample interval; 5.5 second record length; and 80-fold CDP multiplicity. The program layout includes 5 strike lines linking the Exrnouth, Barrow, Dampier and Beagle subbasins and 18 dip lines orthogonal to the principal Mesozoic sub-basin fault systems.

natural gases and 130 core samples from potential source rocks enable resolution of the generation and migration history of petroleum in the Bowen and Surat basins. Biomarker analysis confirmed a pre-Jurassic source for the petroleum.Stable carbon-isotope analysis further indicated a Permian-sourced petroleum and was able to differentiate a very minor and localised Triassic source contribution.The dominant source for the petroleum is terrestrial land plants as well as a minor marine source influence. Lower delta plain and alluvial Permian coals show thehigher liquid potential compared with upper delta plain facies. Initial liquid expulsion from the source rock occurred at vitrinite reflectance 0.65-0.7% and continued to Ro of 1.05%. This was followed by the main phase of gas generation between1.05c/o<Ro<1.4%. The gas generation enabled remobilisation of liquid petroleum for further migration. Biodegradation occurred throughout the basins' petroleummigration history, resulting in an initial regional phase of heavy palaeobiodegradation followed by a second phase of more localised and less intense in-reservoir alteration.

Legacy product - no abstract available

Legacy product - no abstract available

Legacy product - no abstract available

Abstract for initial submission; see Geocat 71429 for conference paper version

The paper discusses the results from the GA-302 2D seismic survey and GA-2436 (RV Tangaroa) marine reconnaissance survey over the Capel and Faust basins, northern Tasman Sea. The integration of seismic, potential field and bathymetric data sets in 3D space at an early stage in the project workflow has assisted in the visualisation of the basin architecture, the interpolation of data between the seismic lines, and the iterative refinement of interpretations. The data sets confirm the presence of multiple depocentres, as previously interpreted from satellite gravity data, with a maximum sediment thickness of 5-7 km. Preliminary interpretation of the seismic data has identified two predominantly Cretaceous syn-rift and two Upper Cretaceous to Neogene sag megasequences overlying a heterogeneous pre-rift basement. The comparison of seismic facies and tectonostratigraphic history with offshore New Zealand and eastern Australian basins suggests the presence of possible Jurassic to Upper Cretaceous coaly and lacustrine source rocks in the pre- and syn-rift, and fluvio-deltaic to shallow marine reservoir rocks in the syn-rift to early post-rift successions. Preliminary 1D basin modelling suggests that the deeper depocentres of the Capel and Faust basins are within the oil and gas windows. Large potential stratigraphic and structural traps are also present.