Seabed environments and shallow geology of the Leveque Shelf, Browse Basin, Western Australia: seabed sediment laser measured grainsize data

In May 2013, Geoscience Australia, in collaboration with the Australian Institute of Marine Science, undertook a marine survey of the Leveque Shelf (survey number SOL5754/GA0340), a sub-basin of the Browse Basin. This survey provides seabed and shallow geological information to support an assessment of the CO2 storage potential of the Browse sedimentary basin. The basin, located on the Northwest Shelf, Western Australia, was previously identified by the Carbon Storage Taskforce (2009) as potentially suitable for CO2 storage. The survey was undertaken under the Australian Government's National CO2 Infrastructure Plan (NCIP) to help identify sites suitable for the long term storage of CO2 within reasonable distances of major sources of CO2 emissions. The principal aim of the Leveque Shelf marine survey was to look for evidence of any past or current gas or fluid seepage at the seabed, and to determine whether these features are related to structures (e.g. faults) in the Leveque Shelf area that may extend to the seabed. The survey also mapped seabed habitats and biota to provide information on communities and biophysical features that may be associated with seepage. This research, combined with deeper geological studies undertaken concurrently, addresses key questions on the potential for containment of CO2 in the basin's proposed CO2 storage unit, i.e. the basal sedimentary section (Late Jurassic and Early Cretaceous), and the regional integrity of the Heyward Formation (the seal unit overlying the main reservoir). The survey collected one hundred and eleven seabed sediment samples that were analysed for their grain size, textural composition and carbonate content. This dataset includes the results of grain size analysis measured by laser diffractometer.

2013年5月，澳大利亚地球科学局（Geoscience Australia）与澳大利亚海洋科学研究所（Australian Institute of Marine Science）合作，对作为布劳湾盆地（Browse Basin）次级盆地的利夫奎陆架（Leveque Shelf）开展海洋地质勘测，勘测编号为SOL5754/GA0340。本次勘测获取海底与浅层地质资料，为布劳湾沉积盆地的二氧化碳封存潜力评估提供支撑。该盆地位于西澳大利亚州西北陆架，此前已被碳封存特别工作组（Carbon Storage Taskforce，2009）认定为具备二氧化碳封存的潜在适宜性。本次勘测依托澳大利亚政府《国家二氧化碳基础设施计划》（National CO2 Infrastructure Plan, NCIP）实施，旨在识别距离主要碳排放源合理区间内的长期二氧化碳封存适宜点位。利夫奎陆架海洋勘测的核心目标为：搜寻海底既往及当前存在的气体或流体渗漏证据，并研判此类渗漏特征是否与延伸至海底的利夫奎陆架区域构造（如断层）存在关联。本次勘测同步绘制了海底生境与生物群落分布图，以获取与渗漏现象相关的生物群落及生物物理特征资料。本研究结合同期开展的深层地质研究，解答了两大关键科学问题：一是盆地拟建二氧化碳封存单元（即晚侏罗世至早白垩世基底沉积剖面）的二氧化碳封存潜力；二是海沃德组（Heyward Formation，主储层上覆盖层单元）的区域完整性。本次勘测共采集111份海底沉积物样本，对其粒度分析（grain size analysis）、结构组成及碳酸盐含量开展测试分析。本数据集包含通过激光衍射仪（laser diffractometer）测得的粒度分析结果。