GABATLAS - Rolling Downs Aquitard - Thickness and Extent

## **Abstract** \n\nThis dataset and its metadata statement were supplied to the Bioregional Assessment Programme by a third party and are presented here as originally supplied.\n\nThe Rolling Downs Aquitard - Thickness and Extent data sets, are part of a set that represents the hydrostratigraphic units of the Great Artesian Basin, which include five major aquifers, four intervening aquitards, and the Cenozoic cover to the GAB. \n\n\n\nThere are five layers in the Rolling Downs Aquitard map data. \n\nA: Formation Extent \n\nB: Outcrop extent \n\nC: Isopach Raster \n\nD: Isopach Contours \n\nE: Data Point Locations \n\n\n\nThe datasets have been derived from the lithostratigraphic intercepts in drillhole data from petroleum exploration wells, water bores, and stratigraphic wells. Seismic correlation and assessment of hydrogeological character based on electrofacies have not been used. The working datasets for this study has been derived primarily from the following databases: \n\n1. PEPS-SA (Petroleum Exploration and Production System - South Australia) (Department of Primary Industries and Regions SA, 2011) \n\n2. WaterConnect Groundwater database (Govt. of SA, 2011) \n\n3. QPED (Queensland Petroleum exploration database) (Geological Survey of Queensland, 2010). \n\n4. GABLOG (Great Artesian Basin Well Log Dataset) (Habermehl, 2001) \n\n5. Additional supplementary information was derived from published reports listed in the following section. \n\n\n\nThis is a regional interpretation for mapping at approximately 1:1 000 000 to produce a broad scale overview, and examination of small areas by collecting extra data is most likely to produce results that differ from this regional interpretation. \n\n\n\nThis dataset and associated metadata can be obtained from www.ga.gov.au, using catalogue number 81677. \n\n\n\nAssociated report reference: \n\nRansley, T., Radke, B., Feitz, A., Kellett, J., Owens, R., Bell, J. and Stewart, G., 2014. Hydrogeological Atlas the Great Artesian Basin. Geoscience Australia. Canberra. \\[available from www.ga.gov.au using catalogue number 79790\\]\n\n## **Dataset History** \n\nSOURCE DATA:\n\nData was obtained from a variety of sources, as listed below: \n\n1. WaterConnect Groundwater database (Govt. of SA, 2011) \n\n2. Great Artesian Basin Well Log Dataset (GABLOG) (Habermehl, M. A., 2001). \n\n3. Petroleum Exploration and Production System - South Australia (PEPS-SA) (Department of Primary Industries and Regions SA, 2011). \n\n4. Queensland Petroleum Exploration Database (QPED) (Geological Survey of Queensland, 2010). \n\n5. Well completion and drill log reports (see references in abstract) \n\n6. Other reports (see references in abstracts) \n\n7. Seismic surveys and associated reports (see seismic references section in abstract) \n\n\n\nMETHOD: \n\nFormation Extent Extents were based on drillhole data (see References) and from Hydrogeology of the Great Artesian Basin Australia (Habermehl & Lau, 1997) for Eromanga and Surat sub-basins. For the Carpentaria Basin, Mesozoic Geology of the Carpentaria and Laura Basins (Geoscience Australia, 2013) was used. \n\n\n\nExtent lines were adjusted to envelop all borehole intercepts of the Hydrostratigraphic unit. This produced some varied and irregular shapes, some patchy regions, and required some interpretation to establish the most likely extent boundary. \n\n\n\nOutcrop Extent \n\nOutcrop extents came from Hydrogeology of the Great Artesian Basin Australia (Habermehl & Lau, 1997) for the Eromanga and Surat sub-basins. For the Carpentaria Basin, Mesozoic Geology of the Carpentaria and Laura Basins (Ransley TR & Smerdon BD, Eds., 2012) was used. Both of these were used minus the Winton-Mackunda Aquifer and the Cenozoic cover.\n\n\n\nIsopach Raster \n\nSource point thickness values calculated from drillhole intercepts were extrapolated using the ESRI ANUDEM Topo-To-Raster surface modeller. Zero thickness constraints were applied at the known extent of the aquifer/aquitard, except in cases where the formation extends beyond the GAB boundary (for example the Precipice formation on the eastern side of the GAB, where the formation is quite thick and is exposed as a cliff). In these cases, constraints were not applied and the software was allowed to model a thickness right up to the GAB boundary. Resulting grids were modified using the ESRI Grid Calculator to set the minimum thickness to 0, and clipped to the aquifer/aquitard extent. \n\n\n\nIsopach Contours \n\nFor a regional picture of the offshore Carpentaria Basin, the thickness of the Normanton Formation and Rolling Downs Aquitard offshore is based on seismic thickness for the entire Rolling Downs Group (RDG) (see references to seismic surveys). Offshore Carpentaria Rolling Downs Group (RDG) cannot be differentiated using seismic surveys, so we have assumed 75% of RDG total thickness is Rolling Downs aquitard, based on stratigraphy in well completion reports for Duyken 1 (Blake et.al. 1984) and Mornington 1 & 2 (Harrison et al. 1961). \n\n\n\nFor the onshore Carpentaria Basin, well completion reports of individual wells (see References), as well as BMR drill Records (Gibson et al., 1974) have been used as a source of thicknesses. Also within the onshore Carpentaria region, lithostratigraphic revision based on electrofacies (McConachie et al., 1994) has enabled distinction of lithostratigraphic units within the onshore Rolling Downs Group north of the Staaten Sub-basin. \n\n\n\nIsopach contours were calculated from the Rolling Downs Aquitard thickness grid using the ESRI Contour Tool. These were calculated at 50m intervals. In most cases the zero contour lines generated by the tool were replaced by the extent of the aquifer due to the erratic nature of the generated lines. In cases where the aquifer/aquitard is thick at the extent, the zero isoline is outside the extent and is not mapped in that area. Isopachs were clipped to the aquifer/aquitard extent.\n\n\n\nData Point Locations \n\nData Point Locations have been derived from the bore hole data collected for this project. Only the location has been included. \n\n\n\nSOFTWARE: All modifications/edits and geoprocessing were performed using ESRI ArcGIS 10 software. \n\n\n\nQAQC: Data sets were searched for errors such as negative thickness, missing data, incorrectly calculated thickness, aquifers/aquitards with missing formations, and false XY data. The data was given a second Q&A after the thickness grids had been calculated. This involve plotting the points and the thickness grid and looking carefully for bad values. Sometimes a false outlier value would cause a 'bullseye' effect on the grid. To check the veracity, nearby data would be compared, and if necessary the original data would be searched check the value. Some petroleum fields would have wildcat picks at certain bore holes and these were compared with nearby boreholes and adjusted or deleted. Additionally, if whole subregions had suspect values the data was check to ensure the relevant data had all been included. Finally, data sets were also checked to ensure the bore whole data recorded the full thickness of the Aquifer. In many cases water bores only go down until a suitable water source is found and often will not penetrate the whole aquifer. This data was considered on a case by case basis, in areas where plenty of suitable data was available they were removed, and in areas of sparse borehole data they were included to establish the occurrence of the formation albeit as a minimum thickness value. \n\n\n\nData has undergone a QAQC verification process in order to capture and repair attribute and geometric errors.\n\n\n\nSee "Metadata.pdf" for complete metadata\n\n## **Dataset Citation** \n\nGeoscience Australia (2015) GABATLAS - Rolling Downs Aquitard - Thickness and Extent. Bioregional Assessment Source Dataset. Viewed 10 December 2018, http://data.bioregionalassessments.gov.au/dataset/0c4f0e0e-2d1d-4dee-9a57-36ecdd1d9a1f.## **摘要** 本数据集及其元数据声明由第三方提供给生物区域评估计划（Bioregional Assessment Programme），此处按原始提供的形式呈现。 《Rolling Downs隔水层（Rolling Downs Aquitard）厚度与分布数据集》是代表大自流盆地（Great Artesian Basin）水文地层单元（hydrostratigraphic units）的数据集组的一部分，该数据集组包含5个主要含水层、4个相邻隔水层以及覆盖在大自流盆地之上的新生代覆盖层（Cenozoic cover）。 Rolling Downs隔水层地图数据包含5个图层： A: 地层分布范围 B: 露头分布范围 C: 等厚栅格数据 D: 等厚等值线 E: 数据点位置 本数据集源自石油勘探井（petroleum exploration wells）、水井钻孔（water bores）以及地层井（stratigraphic wells）的钻井数据中的岩石地层截获数据（lithostratigraphic intercepts），未使用地震对比以及基于电相（electrofacies）的水文地质特征评估方法。本研究的工作数据集主要来源于以下数据库： 1. 南澳石油勘探与生产系统（Petroleum Exploration and Production System - South Australia）（南澳第一产业与区域部，2011年） 2. WaterConnect地下水数据库（WaterConnect Groundwater database）（南澳政府，2011年） 3. 昆士兰州石油勘探数据库（Queensland Petroleum exploration database, QPED）（昆士兰州地质调查局，2010年） 4. 大自流盆地测井数据集（Great Artesian Basin Well Log Dataset, GABLOG）（Habermehl，2001年） 5. 额外补充信息来源于下文列出的已发表报告。 本研究为约1:100万比例尺制图的区域解译成果，旨在提供大范围概览；若通过收集额外数据对小区域进行细致研究，所得结果大概率与本区域解译成果存在差异。 本数据集及相关元数据可通过目录编号（catalogue number）81677在www.ga.gov.au获取。 相关报告参考文献： Ransley, T., Radke, B., Feitz, A., Kellett, J., Owens, R., Bell, J. 及 Stewart, G., 2014年。《大自流盆地水文地质图集》（Hydrogeological Atlas the Great Artesian Basin）。澳大利亚地质科学局（Geoscience Australia），堪培拉。\[可通过目录编号79790在www.ga.gov.au获取\] ## **数据集历史** ### 源数据： 数据来源于以下多种渠道： 1. WaterConnect地下水数据库（WaterConnect Groundwater database）（南澳政府，2011年） 2. 大自流盆地测井数据集（GABLOG）（Habermehl, M. A., 2001年） 3. 南澳石油勘探与生产系统（PEPS-SA）（南澳第一产业与区域部，2011年） 4. 昆士兰州石油勘探数据库（QPED）（昆士兰州地质调查局，2010年） 5. 钻井完井与测井报告（详见摘要中的参考文献） 6. 其他报告（详见摘要中的参考文献） 7. 地震勘探及相关报告（详见摘要中的地震参考文献部分） ### 制作方法： #### 地层分布范围 地层分布范围基于钻井数据（详见参考文献）以及《澳大利亚大自流盆地水文地质》（Habermehl & Lau, 1997年），适用于埃罗曼加（Eromanga）与瑟拉特（Surat）次盆地。对于卡奔塔利亚（Carpentaria）盆地，则采用《卡奔塔利亚与劳拉盆地中生代地质》（Geoscience Australia, 2013年）。 分布范围线经过调整，以覆盖所有水文地层单元的钻孔截获点，由此产生了形态各异、不规则的区域，部分区域存在斑块状分布，需要通过解译确定最合理的分布边界。 #### 露头分布范围 露头分布范围来源于《澳大利亚大自流盆地水文地质》（Habermehl & Lau, 1997年），适用于埃罗曼加与瑟拉特次盆地。对于卡奔塔利亚盆地，则采用《卡奔塔利亚与劳拉盆地中生代地质》（Ransley TR & Smerdon BD, Eds., 2012年）。上述两份资料均剔除了温顿-马昆达含水层（Winton-Mackunda Aquifer）与新生代覆盖层。 #### 等厚栅格数据 基于钻孔截获点计算的源点厚度值，通过ESRI ANUDEM地形转栅格表面建模工具（ESRI ANUDEM Topo-To-Raster surface modeller）进行外推。在已知含水层/隔水层分布范围内，设置厚度为0的约束条件，但当地层延伸至大自流盆地边界以外时（例如大自流盆地东侧的悬崖地层（Precipice formation），该地层厚度较大且以悬崖形式出露），则不施加该约束，允许软件将厚度模型延伸至大自流盆地边界。最终生成的栅格通过ESRI栅格计算器（ESRI Grid Calculator）进行修正，将最小厚度设置为0，并裁剪至含水层/隔水层的分布范围。 #### 等厚等值线 针对卡奔塔利亚盆地近海区域的概览图，Normanton地层与Rolling Downs隔水层的厚度基于整个Rolling Downs群（Rolling Downs Group, RDG）的地震厚度（详见地震勘探参考文献）。由于地震勘探无法区分卡奔塔利亚近海的Rolling Downs群（RDG），因此基于Duyken 1井（Blake et.al. 1984年）与Mornington 1、2井（Harrison et al. 1961年）的完井报告地层数据，假设Rolling Downs隔水层厚度占Rolling Downs群总厚度的75%。 对于卡奔塔利亚盆地陆上区域，厚度数据来源于单井完井报告（详见参考文献）以及BMR钻井记录（Gibson et al., 1974年）。此外，在卡奔塔利亚陆上区域，基于电相的岩石地层修订工作（McConachie et al., 1994年）已实现对Staaten次盆地以北陆上Rolling Downs群内的岩石地层单元进行区分。 等厚等值线通过ESRI等值线绘制工具（ESRI Contour Tool），基于Rolling Downs隔水层厚度栅格计算生成，等值线间隔为50米。多数情况下，工具生成的零等值线会被替换为含水层分布范围，这是因为生成的零等值线存在不规则性。当含水层/隔水层在分布边界处厚度较大时，零等值线会位于分布范围以外，因此不会在该区域绘制。最终等厚线将被裁剪至含水层/隔水层的分布范围。 #### 数据点位置 数据点位置来源于本项目收集的钻孔数据，仅保留点位坐标信息。 ### 软件工具 所有修改、编辑与地理处理操作均通过ESRI ArcGIS 10软件（ESRI ArcGIS 10）完成。 ### 质量控制与质量保证（QAQC, Quality Assurance/Quality Control） 数据集被逐一排查错误，包括负厚度、数据缺失、厚度计算错误、含水层/隔水层缺失地层以及错误的XY坐标数据。在厚度栅格计算完成后，开展了第二轮质量检查：包括绘制点位与厚度栅格图，仔细检查异常值。有时错误的异常值会在栅格上产生“靶心效应”（bullseye effect）。为验证数据可靠性，会对比邻近点位的数据，必要时会检索原始数据核对数值。部分油田的某些钻孔存在初探井估算值，需与邻近钻孔对比，对其进行调整或删除。此外，若整个次区域（subregions）的数值存在可疑之处，则会检查相关数据是否已完整纳入。最后，还会检查钻孔数据是否记录了含水层的完整厚度——多数情况下，水井钻孔仅钻至合适的水源层位，通常不会穿透整个含水层，此类数据将按具体情况处理：在拥有充足可用数据的区域，此类数据将被移除；在钻孔数据稀疏的区域，则保留该数据以确定地层的存在，此时其数值仅作为最小厚度值。 本数据集已通过QAQC验证流程，以捕获并修正属性与几何错误。 完整元数据请参见“Metadata.pdf”。 ## **数据集引用** 澳大利亚地质科学局（Geoscience Australia）（2015年） GABATLAS - Rolling Downs隔水层厚度与分布。生物区域评估源数据集。2018年12月10日查阅，http://data.bioregionalassessments.gov.au/dataset/0c4f0e0e-2d1d-4dee-9a57-36ecdd1d9a1f。