Quantification of leakage into the atmosphere from geologically stored CO2 is achievable by means of atmospheric monitoring techniques if the position of the leak can be located and the perturbation above the background concentration is sufficiently large for discrimination. Geoscience Australia and the CO2CRC have recently constructed a site in northern Canberra for the controlled release of greenhouse gases. This facility enables the simulation of leak events and provides an opportunity to investigate techniques for the detection and quantification of emissions of CO2 (and other greenhouse gases) into the atmosphere under controlled conditions. The facility is modelled on the ZERT controlled release facility in Montana. The first phase of the installation is complete and has supported an above ground, point source, release experiment (e.g. simulating leakage from a compromised well). Phase 2 involves the installation of a shallow underground horizontal well for line source CO2 release experiments and this will be installed during the first half of 2011. A release experiment was conducted at the site to explore the application of a technique, termed atmospheric tomography, to simultaneously determine the location and emission rate of a leak when both are unknown. The technique was applied to the release of two gas species, N2O and CO2, with continuous sampling of atmospheric trace gas concentrations from 8 locations 20m distant from a central release point and measurement of atmospheric turbulence and dispersive conditions. The release rate was 1.10 ± 0.02 g min-1 for N2O and 58.5 ± 0.4 g min-1 for CO2 (equivalent to 30.7 ± 0.2 tonnes CO2 yr-1). Localisation using both release species occurred within 0.5 m (2% error) of the known location. Determination of emission rate was possible to within 7% for CO2 and 5% for N2O.

In the 2011/12 Budget, the Australian Government announced funding of a four year National CO2 Infrastructure Plan (NCIP) to accelerate the identification and development of suitable long term CO2 storage sites, within reasonable distances of major energy and industrial emission sources. The NCIP funding follows on from funding announced earlier in 2011 from the Carbon Storage Taskforce through the National Carbon Mapping and Infrastructure Plan and previous funding recommended by the former National Low Emissions Coal Council. Four offshore sedimentary basins and several onshore basins have been identified for study and pre-competitive data acquisition.

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.

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

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.

The Early Cretaceous Gage Sandstone and South Perth Shale formations are one of the most prospective reservoir-seal pairs in the Vlaming Sub-basin. Plays include post-breakup pinch-outs with the South Perth Shale forming a top seal. The Gage reservoir has porosities of 23-30% and permeabilities of 200-1800 mD and was deposited in palaeotopographic lows of the Valanginian breakup unconformity. This is overlain by the thick deltaic South Perth (SP) Supersequence. To characterise the reservoir-seal pair, a detailed sequence stratigraphic analysis was conducted by integrating 2D seismic interpretation, well log analysis and new biostratigraphic data. The palaeogeographic reconstructions for the Gage reservoir are based predominantly on the seismic facies mapping, whereas SP Sequence reconstructions are derived from mapping higher-order prograding sequences and establishing changes in sea level and sediment supply. The Gage reservoir forms part of a sand-rich submarine fan system and was deposited in water depths of > 400 m. It ranges from confined canyon fill to fan deposits on a basin plain. Directions of sediment supply are complex, with major sediment contributions from a northern and southern canyon adjacent to the Badaminna Fault Zone. The characteristics of the SP Supersequence differ markedly between the northern and southern parts of the sub-basin due to variations in palaeotopography and sediment supply. Palaeogeographic reconstructions reveal a series of regressions and transgressions leading to infilling of the palaeo-depression. Seven palaeogeographic reconstructions for the SP Supersequence portray a complex early post-rift depositional history in the central Vlaming Sub-basin. The developed approach could be applicable for detailed studies of other sedimentary basins

Poster for 2008 CO2CRC Symposium.

Atmospheric monitoring of CO2 geological storage has developed from a concept to reality over less than a decade. Measurements of atmospheric composition and surface to air fluxes are now being made at onshore test sites, pilot projects, operational projects and likely future storage regions around the world. The motivation for atmospheric monitoring is usually to detect potential leakage from CO2 storage activities that might affect health and safety or to test the efficacy of carbon capture and storage (CCS) as a climate mitigation option. We have focused on the mitigation requirement, which involves determining whether potential leakage is below a maximum acceptable rate. Climatic considerations suggest that the maximum leakage rate of stored CO2 should be very small, of the order of 0.01% of that stored per year, globally averaged. Monitoring operational CO2 storage sites to confirm that potential leakage to the atmosphere is below this rate and to locate and quantify the any leakage flux can be a challenge, mainly because of the large and variable CO2 concentrations and fluxes in ecosystems and urban environments. We have developed and assessed atmospheric techniques during field experiments, during 4 years of monitoring the CO2CRC Otway Project, and by using model simulations. From this experience we are able to make recommendations about suitable technologies and strategies to optimise the capability of atmospheric monitoring of CCS in different environments. Abstract for paper to be presented at CO2CRC Research Symposium 2010, 1-3 December 2010, Melbourne

The release of fluid to the seabed from deeper sources is a process that can influence seabed geomorphology and associated habitats, with pockmarks a common indicator. In May 2012, Geoscience Australia led a multidisciplinary marine survey in Joseph Bonaparte Gulf, to facilitate an assessment of the potential for fluid leakage associated with geological storage of CO2 at depth within the Petrel Sub-basin. Multibeam bathymetry and backscatter mapping (652 km2), combined with acoustic sub-bottom profiling (655 line-km) and geomorphological and sediment characterisation of the seabed was undertaken. Seabed geomorphic environments identified from 2 m resolution bathymetry include carbonate banks and ridges, palaeochannels, pockmark fields and fields of low amplitude hummocks. This paper focuses on pockmarks as indicators of fluid seepage from the subsurface. Three principal pockmark morphologies (Type I, II and III) are present with their distribution non-random. Small unit (Type I) depressions occur on plains and in palaeochannels, but are most commonly within larger (Type II) composite pockmarks on plains. Type III pockmarks, intermediate in scale, are only present in palaeochannels. The timing of pockmark formation is constrained by radiocarbon dating to 14.5 cal ka BP, or later, when a rapid rise in sea-level would have flooded much of outer Joseph Bonaparte Gulf. Our data suggest the principal source of fluids to the seabed is from the breakdown of organic material deposited during the last glacial maxima lowstand of sea-level, and presently trapped beneath marine sediments. These results assist in ameliorating uncertainties associated with potential CO2 storage in this region.

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 Autonomous Underwater Vehicle (AUV) still image data acquired during survey GA0345/GA0346/TAN1411. Following mapping with the shipboard multibeam, higher-resolution multibeam data were acquired in targeted areas using a Kongsberg Simrad EM2000 system mounted to the Fugro Echo Surveyor V (ES-5) AUV. This instrument had a depth rating of 3000 m, and surveyed the seafloor according to a pre-programmed mission plan. The AUV was fitted with a camera and light system designed to produce images of equal width and height (in the context of this survey, the images comprised 8 m by 8 m of seafloor). The equipment consisted of a light sensitive NEO 11 Megapixel 35 mm monochrome CCD (4008 x 2672) camera and two LED panels, each comprising 360 LEDs. High-resolution multibeam bathymetric data was collected together with side scan sonar and sub bottom profile data at an elevation of 30 m above the seafloor, and at line spacing's of 100 m. Overlapping high-resolution still photographs (captured every second) were then acquired on the survey lines at an elevation of 8 m above the seafloor. The AUV was equipped with an advanced real-time Aided Inertial Navigation System, which calculated the position, velocity and altitude of the vehicle and a HiPAP 500 USBL system was used to acoustically position the AUV. Underwater imagery was collected from two AUV missions in study Areas 3 and 4. During the 2nd AUV mission on 22 October, the vehicle encountered an obstruction on the seabed and became trapped despite commencing an emergency ascent sequence. The AUV was subsequently recovered from the seabed during salvage operations incorporated into the ROV phase of survey operations. A total of 24 877 still images were acquired in Area 3 and 20 743 in Area 4 over 58 and 56 line kilometres, respectively. Still images (.jpg files) are located in folder 'TAN1411_AUV_STILLS' with sub-folders named according to gear code (AUV= Autonomous Underwater Vehicle), mission and study Area (e.g. AUV_M2_A3 = still images acquired during AUV mission 2 in Area 3). USBL (Ultra-short baseline) text files (`TileCam.idx) are located in each sub-folder and provide continuous navigational information on location, time (UTC) and depth of AUV still imagery transect lines.