In 2008, the Australian Parliament debated and passed the first national legislation to establish a title system of access and property rights for greenhouse gas (CO2) storage in offshore waters - the Offshore Petroleum and Greenhouse Gas Storage Act 2006 (the Act). The Act provides for petroleum titles and greenhouse gas storage titles to coexist. To manage possible interactions between petroleum and CO2 storage operations, the Act introduced a test to determine whether activities under one title would pose a significant risk of a significant adverse impact (SROSAI test) on pre-existing rights and assets under the other title. Where petroleum and CO2 storage projects are proposed in the same area, the Act provides for commercial agreements between petroleum and CO2 storage proponents. It is only in the absence of any such commercial agreements that the regulator will have to decide whether an activity under one title would pose a significant risk of a significant adverse impact on the operations within the other title area. The SROSAI test is based on three core parameters: - the probability of the occurrence of an adverse impact; - the cost of the adverse impact on the project; and - the total resource value of the project. In estimating the cost of an adverse impact the regulator will take into consideration whether the adverse impact will result in: - any increase in capital or operating costs; - any reduction in rate of recovery of petroleum or rate of injection of CO2; - any reduction in the quantity of the petroleum to be recovered or CO2 stored. Safety and environmental impacts would be considered in estimating costs, only if those impacts would contribute to an increase in capital or operating costs, or reduction in petroleum recovery or CO2 injection. Etc

Carbon capture and storage is a mitigation strategy that could rapidly reduce CO2 emissions from high emission sources. However, the exploration and assessment of reservoirs for the geological storage of CO2 is a complicated science commonly hampered by large uncertainties. The major hurdles lie in correctly assessing the prospectivity of basin plays, and ultimately of play fairways suitable for CO2 storage. On the North West Shelf of Australia, turbidite deposits are a common depositional system and many are considered prospective for CO2 storage in this emission intensive part of Australia. Using an integrated reservoir modelling approach, this study assessed the storage potential of the Caswell Fan turbidite in the Browse Basin, Western Australia. A detailed seismic interpretation utilising both 2D and 3D seismic and four previously drilled wells, provided the sequence stratigraphic framework for a detailed reservoir evaluation. The Fan was deposited in a basin floor fan setting within a lowstand systems tract, which provided optimal conditions for sequestration due to the sandstone's extended geometry, sorting, and high net-to-gross ratios, all overlain by a regional marine claystone seal. Through 3D static geological modelling it was determined that the Caswell Fan had an estimated storage capacity of approximately 300 million tonnes of CO2. This largely unconfined basin floor fan represents one of several plays along the North West Shelf of Australia, which could provide suitable CO2 storage formations for the carbon capture and storage industry.

Poster for 2008 CO2CRC Symposium.

Underground gas storage (UGS) facilities provide a wealth of information, which can be used to better understand various aspects of CO2 storage in depleted reservoirs. In some cases UGS facilities can provide important site specific information for carbon storage projects that are planned in similar formations in close proximity. In this paper, we discuss the various ways in which UGS facilities can be used to extract important information, and when possible we draw upon information from the Iona gas storage facility in Australia's Otway basin. The Iona facility is located 20 km away from the CO2CRC Otway Project, in which CO2 65445 tonnes of 77 mole% carbon dioxide, 20 mole% methane and 3 mole% other gas components (containing about 58000 tonnes of carbon dioxide) was injected into the Waarre C formation over a 17 month period. In this paper, we compare the factors that control CO2 seal capacity and discuss how UGS facilities can provide information on sustainable column heights either limited by faults or by cap rocks. We also present dynamic modeling results in which information is gained regarding injectivity, pressure evolution of the reservoir, storage capacity and maximum fluid pressures sustained by the faults. Understanding such parameters is important for the safe operation of any carbon storage project, be it on a demonstration or industrial scale.

Geoscience Australia (GA) conducted a marine survey (GA0345/GA0346/TAN1411) of the north-eastern Browse Basin (Caswell Sub-basin) between 9 October and 9 November 2014 to acquire seabed and shallow geological information to support an assessment of the CO2 storage potential of the basin. The survey, undertaken as part of the Department of Industry and Science's National CO2 Infrastructure Plan (NCIP), aimed to identify and characterise indicators of natural hydrocarbon or fluid seepage that may indicate compromised seal integrity in the region. The survey was conducted in three legs aboard the New Zealand research vessel RV Tangaroa, and included scientists and technical staff from GA, the NZ National Institute of Water and Atmospheric Research Ltd. (NIWA) and Fugro Survey Pty Ltd. Shipboard data (survey ID GA0345) collected included multibeam sonar bathymetry and backscatter over 12 areas (A1, A2, A3, A4, A6b, A7, A8, B1, C1, C2b, F1, M1) totalling 455 km2 in water depths ranging from 90 - 430 m, and 611 km of sub-bottom profile lines. Seabed samples were collected from 48 stations and included 99 Smith-McIntyre grabs and 41 piston cores. An Autonomous Underwater Vehicle (AUV) (survey ID GA0346) collected higher-resolution multibeam sonar bathymetry and backscatter data, totalling 7.7 km2, along with 71 line km of side scan sonar, underwater camera and sub-bottom profile data. Twenty two Remotely Operated Vehicle (ROV) missions collected 31 hours of underwater video, 657 still images, eight grabs and one core. This catalogue entry refers to chlorophyll a, b, c and phaeophytin a conentrations in the upper 2 cm of seabed sediments.

In 2012, Geoscience Australia carried out marine environmental surveys in the Vlaming Sub-basin, Perth Basin (GA0334) and Petrel Sub-basin, Bonaparte Basin (GA0335). The purpose of these surveys was to gather pre-competitive geophysical and biophysical data on the seabed environments within targeted areas of the sub-basins to help with the assessment of CO2 storage potential. Over the duration of the Vlaming Sub-basin survey, approximately 650 km2 of multibeam sonar data and 2300 line km of sub-bottom profiler (SBP) data were collected. Also acquired was 6.65 km2 of sidescan sonar imagery, 4.25 km of video footage and 89 grab samples. More than 650 km2 of multibeam sonar data and 650 line km of multi-channel SBP data was acquired during the Petrel Sub-basin survey. A total of 114 sampling operations recovered shallow samples or video footage for sedimentological, biological and chemical analysis. These datasets have been used to investigate possible fluid pathways in the shallow subsurface geology. In the Petrel Sub-basin, banks, palaeo-channels, plains, ridges and pockmark fields characterise the seafloor. While in the Vlaming Sub-basin, a Holocene sediment-starved system was observed with shallow valleys, shallow terraces, sediment mega-ripples and prominent ridges on the seafloor. The complexity of these environments and the general spatial correlation between seabed features and the subsurface geology, suggest that a large number of processes have interacted to give rise to the present geomorphology of the continental shelves. These new datasets have been used to support the regional assessment of CO2 storage prospectivity in the Vlaming and Petrel sub-basins.

The Petrel Sub-basin Marine Survey (GA0335/SOL5463) was undertaken in May 2012 by Geoscience Australia in collaboration with the Australian Institute of Marine Science (AIMS), as part of the Australian Government's National Low Emission Coal Initiative (NLECI). Its purpose was to acquire pre-competitive geophysical and biophysical data on shallow seabed environments within two targeted areas to support assessment of CO2 storage potential. The geophysical acquisition consisted of multibeam sonar mapping of sea floor morphology and multi-channel sub bottom profiling of the shallow sub surface geology. The aim of sub bottom profiling was to investigate regional seal breaches and potential fluid pathways by providing high resolution images connecting the sea floor map to regional seismic reflection data acquired concurrently in the area. The sub bottom profiler data were acquired aboard the AIMS research vessel (RV) Solander along 51 lines, totalling 654 line km in the Petrel Sub-basin of the Bonaparte Basin. Acquisition employed a Squid 2000 sparker as the source and a 24 channel Microeel streamer for the receivers. Group interval was 3.125 m and shot interval 6.25 m, resulting in 6 fold data. Record length was 500 ms with a sample interval of 0.25 ms. Some problems in acquisition needed to be addressed in processing. Firstly, sea conditions were far from smooth for most of the voyage. Obvious relative motion occurred between the source and the streamer, and along the streamer itself, due to the ocean swell. In some cases, acquisition commenced while the vessel was still turning onto the line and the streamer was not straight in line behind the stern. Finally, malfunction of the sparker on some half dozen lines resulted in gaps in the coverage, which could not be filled in later, due to bad weather reducing the time for the survey. Multichannel seismic reflection processing was able to compensate for some of the limitations of sparker acquisition. Mutes and filters were necessary to remove the worst of the noise, including leaked timing pulse and swell noise. Surface related multiple elimination (SRME) successfully attenuated the water bottom and later multiples. Non surface consistent trim statics were able to correct for the relative motion of the sparker and the streamer, thereby allowing alignment of reflections prior to stack, which improved the signal to noise. Minimum entropy deconvolution was a critical step in both suppressing ghosting and enhancing latent high frequencies in the data, thus improving the resolution. Migration was necessary to correctly image small channels by collapsing diffractions. Finally tidal static corrections were essential to remove mis-ties in high frequency data. The processing stream has been well documented, along with scripts employed to handle the large amount of data efficiently and consistently. This record is a manual for a much more rigorous way of processing multi-channel sparker data, and details a work flow that can be implemented within Geoscience Australia and used for future surveys. The final migrated seismic data proved to be very high resolution, allowing delineation of multiple episodes of channelling in the top 100 m of sediment. Comparison of the sub bottom profiles with older regional seismic reflection data showed just how much more detail is available in the region critical for mapping deeper faults and fluid pathways to features on the sea floor. Acquisition and processing of the sub bottom profiler data surpassed the survey expectations.

Geoscience Australia is investigating the suitability of offshore sedimentary basins as potential CO2 storage sites. In May 2012 a seabed survey (GA0335/SOL5463) was undertaken in collaboration with the Australian Institute of Marine Science to acquire baseline marine data in the Petrel Sub-basin, Joseph Bonaparte Gulf. The aim was to collect information on possible connections (faults and fluid pathways) between the seabed and key basin units, and to characterise seabed habitats and biota. Two areas were surveyed (Area 1: 471 km2, depth ~ 80-100 m; Area 2: 181 km2, depth ~ 30-70 m), chosen to investigate the seabed over the potential supercritical CO2 boundary (Area 1) and the basin margin (Area 2), with Area 2 located around Flat Top 1 Well. Data analysed include multibeam sonar bathymetry and backscatter, seabed samples and their geochemical and biological properties, video footage and still images of seabed habitats and biota, and acoustic sub-bottom profiles. Pockmarks, providing evidence for fluid release, are present at the seabed, and are particularly numerous in Area 1. Area 1 is part of a sediment-starved, low-relief section of shelf characterised by seabed plains, relict estuarine paleochannels, and low-lying ridges. Facies analysis and radiocarbon dating of relict coastal plain sediment indicates Area 1 was a mangrove-rich environment around 15,500 years ago, transgressed near the end of the Last Glacial period (Meltwater Pulse 1A). Modern seabed habitats have developed on these relict geomorphic features, which have been little modified by recent seabed processes. Seabed habitats include areas of barren and bioturbated sediments, and mixed patches of sponges and octocorals on hardgrounds. In the sub-surface, stacked sequences of northwest-dipping to flat-lying, well-stratified sediments, variably incised by palaeochannels characterise the shallow geology of Area 1. Some shallow faulting through these deposits was noted, but direct linkages between seabed features and deep-seated faults were not observed. Area 2 is dominated by carbonate banks and ridges. Low-lying ridges, terraces and plains are commonly overlain by hummocky sediment of uncertain origin. Pockmarks are present on the margins of banks, and on and adjacent to ridges. Despite the co-location of banks and ridges with major faults at depth, there is a lack of direct evidence for structural connectivity, particularly because of significant acoustic masking in the sub-surface profiles of Area 2. While no direct structural relationship was observed in the acoustic sub-bottom profiles between these banks, ridges and faults visible in the basin seismic profiles, some faults extend through the upper basin units towards the seabed on the margin of Area 2. No evidence was detected at the seabed for the presence of thermogenic hydrocarbons or other fluids sourced from the basin, including beneath the CO2 supercritical boundary. The source of fluids driving pockmark formation in Area 1 is most likely decomposing mangrove-rich organic matter within late Pleistocene estuarine sediments. The gas generated is dominated by CO2. Additional fluids are potentially derived from sediment compaction and dewatering. Conceptual models derived from this are being used to inform regional-scale assessments of CO2 storage prospectivity in the Petrel Sub-basin.

This GHGT-12 conference paper hightlights some results of GA's work on "Regional assessment of the CO2 storage potential of the Mesozoic sucession in the Petrel Sub-basin, Northern Territory, Australia. Record 2014/11".

Geoscience Australia conducted a marine seismic survey (GA-0352) over poorly defined areas of the Gippsland Basin between 5th of April to the 24th of April 2015. The aim was to acquire industry-standard precompetitive 2D seismic data, Multi-beam echo-sounder (MBES) and sub-bottom profiling (SBP) data to support an assessment of the CO2 storage potential of the basin. The survey, undertaken as part of the Department of Industry and Science's National CO2 Infrastructure Plan (NCIP), aimed to identify and characterise indicators of natural hydrocarbon or fluid seepage that may indicate compromised seal integrity in the region. The data collected during this survey will enhance sequence stratigraphic studies in the Gippsland Basin that provide constraints on the most suitable areas for storage of CO2 and help to identify potential CO2 storage reservoirs. The survey was conducted by Gardline CGG vessel MV Duke The data collected during the survey are available for free download from the Geoscience Australia website. This dataset include all the bathymetry data collected during the survey.<p><p>This dataset is not to be used for navigational purposes.