b'AEGC 2021Short abstractsintriguing, complex structural history, and large potentialof the Jurgurra Terrace structural province, with good quality petroleum traps. reservoirs of Devonian age proven in this area.Basin modelling in the centre of the Bamaga Basin where the sedimentary section is deepest shows that the sediments are mature for petroleum generation with the hydrocarbon phase31: Controls on organic matter accumulation in the being either oil or gas, although gas is more likely, especiallyMesoproterozoic: Insights from the stratigraphic below 2000m. modelling of the Velkerri Formation of the Beetaloo Analysis of the available data indicates that in the oil generationBasin (Northern Territory, Australia)zone there are many targets each of which has the potential toDr Vincent Crombez 1, Dr Mohinudeen Faiz2, Dr Claudio Delle hold Prospective Resources of more than 250 MMstb of oil, thePiane1 and Dr Marcus Kunzmann2largest of which could hold 660 MMstb oil. In the gas generation zone, there are also numerous targets, each with the potential1 CSIRO Energy, Deep Earth Imagingto hold Prospective Resources of 1 Tcf or more gas, the largest of2 CSIROwhich could hold as much as 2.5 Tcf gas.Ability to understand and predict the distribution of The water depth (60 m), closeness to shore (150 km) andprimary organic content in a basin is key when exploring reasonable target depths means exploring the Bamaga Basin isfor unconventional hydrocarbons. Many pathways lead operationally and commercially attractive. to the formation of organic-rich rocks through numerous combinations between rate of primary productivity, organic matter preservation, and dilution that occur in sedimentary 29: New age dating of evaporites in Canning Basin,basins. It is likely that: (1) primary productivity will vary WA, Australia. A case study based on samples from thetemporally and spatially, (2) preservation will be affected by the Frome Rocks salt diapir basins physiography (e.g., open vs. restricted) and the burial efficiency, and (3) dilution will be a function of the stratigraphic Miss Fionna McNee, Mr Frank Glass, Mr John Gorter, Mr Markevolution. If the vertical and lateral variations of each of these Devereux, Mr David Long, Mr Sam Oldham and M iss Amyfactors is not understood, it is difficult to quantify the impact of Millar their interaction on organic matter accumulation.The age of evaporitic units in the Kidson Sub-basin of theIn the present work, we focus on the Meso-Proterozoic Canning Basin have been assigned to be of Late OrdovicianVelkerri Formation, an unconventional hydrocarbon self-to Early Silurian age through the dating of the sedimentarysourced shale reservoir currently being the target of sequences within the Mallowa Salt. exploration and appraisal activities in the Beetaloo Sub-basin. The Frome Rocks 1 exploration well was drilled in 1959 on theUsing well data and geochemical analyses, we reconstruct Jurgurra Terrace on the southern margin of the Fitzroy Troughthe stratigraphic architecture of this interval and suggest a and encountered 600 m of salt down to a total depth (TD) of thegeological model for the accumulation of organic matter. well at 1220 mMD (1137 mTVDSS). Based on seismic data, thisThen, using stratigraphic modelling, we simulate the salt sequence is interpreted to be part of a diapiric structure thatevolution of the basin in the Proterozoic and feed the new resulted from the rapid deposition of Carboniferous/Permianresults into the previously established geological model sediments over a thick evaporitic sequence. It is generallyfor organic-matter accumulation. In a last step, we run accepted that the evaporite sequence encountered in themultiple realisations of the model while changing the input Frome Rocks 1 well was deposited contemporaneously with theparameters that influence primary productivity, oxygen Mallowa Salt in the nearby Kidson Sub-basin. renewal in water column, and sediment supply, which allows for the quantification of their effects on organic matter This paper presents an alternative model that suggests thataccumulation. This study emphasizes that while being an evaporitic salt sequence over the Jurgurra Terrace wasdeposited in the Meso-Proterozoic, high primary productivity deposited during the initial opening of the Fitzroy Troughis necessary to establish organic richness of the shale. In during the Middle Devonian and prior to the deposition ofaddition, this study shows that the controls on organic matter the carbonate/claystone sequences of the Gogo and Pillaravaries spatially and temporarily, depending on the location Formations. within the basin and the stratigraphic interval.The presence of several evaporitic deposits within the Mellinjerie Formation of Middle Devonian age encountered32: Petroleum systems model for source- rock-reservoir in wells surrounding the Fitzroy Trough supports this ageevaluation in the Beetaloo Sub-basininterpretation, while global indications for a major sea level drop in the Early to Middle Devonian allow for theDr Moinudeen Faiz 1, Dr Vincent Crombez2, Dr Claudio Delle development and generation of evaporitic conditions in anPiane2, Mr Nicholas Lupton1 and Mr Michael Camilleri1isolated shallow marine basin that predates the opening of the Fitzroy Trough. 1 CSIRO Energy2 CSIRO Energy, Deep Earth ImagingOngoing work includes palynological and radiogenic dating ofThe Beetaloo Sub-basin comprises the oldest known samples of the salt and overlying sediments from several recentpetroleum system in the world with the Mesoproterozoic mineral holes drilled on the Frome Rocks salt diapir. shales being prolific source rocks and proven as productive The confirmation of evaporites of Middle Devonian ageunconventional reservoirs. The main unconventional reservoir would significantly increase the hydrocarbon prospectivitytargets include gas- to liquids mature shales of the Velkerri AUGUST 2021 PREVIEW 66'