The Collaborative Research Centre for Greenhouse Gas Technologies (CO2CRC) Program 3.2 Risk Assessment is working toward a risk assessment procedure that integrates risk across the complete CCS system and can be used to meet the needs of a range of stakeholders. Any particular CCS project will hold the interest of multiple stakeholders who will have varied interests in the type of information and in the level of detail they require. It is unlikely that any single risk assessment tool will be able to provide the full range of outputs required to meet the needs of regulators, the general public and project managers; however, in many cases the data and structure behind the outputs will be the same. In using a suite of tools, a well designed procedure will optimize the interaction between the scientists, engineers and other experts contributing to the assessment and will allow for the required information to be presented in a manner appropriate for each stakeholder. Discussions of risk in CCS, even amongst the risk assessment community, often become confused because of the differing emphases on what the risks of interest are. A key question that must be addressed is: 'What questions is the risk analysis trying to answer?' Ultimately, this comes down to the stakeholders, whose interests can be broken into four target questions: - Which part of the capture-transport-storage CCS system? - Which timeline? (project planning, project lifespan, post closure, 1,000 years, etc) - Which risk aspect? (technical, regulatory, economic, public acceptance, or heath safety and environment) - Which risk metric? (Dollars, CO2 lost, dollars/tonne CO2 avoided, etc.) Once the responses to these questions are understood a procedure and suite of tools can be selected that adequately addresses the questions. The key components of the CO2CRC procedure we describe here are: etc

As part of the National CO2 Infrastructure Plan (NCIP) Geoscience Australia is undertaking evaluation of the Gage Sandstone and the overlying South Perth Shale for the long-term storage of CO2. Initial assessment of the seismic data identified widespread fault reactivation and seismic anomalies potentially indicating hydrocarbon seepage. Some of the seismic anomalies clearly correlate with reactivated faults, but not all of them. The study highlights the importance of developing a detailed understanding of spatial variability in seal quality and history of fault reactivation both for petroleum exploration and CO2 storage assessments.

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.

Between March 2008 and August 2009, 65,445 tonnes of ~75 mol% CO2 gas were injected in a depleted natural gas reservoir approximately 2000 m below surface at the Otway project site in Victoria, Australia. Groundwater flow and composition were monitored biannually in 2 near-surface aquifers between June 2006 and March 2011, spanning the pre-, syn- and post-injection periods. The shallow (~0-100 m), unconfined, porous and karstic aquifer of the Port Campbell Limestone and the deeper (~600-900 m), confined and porous aquifer of the Dilwyn Formation contain valuable fresh water resources. Groundwater levels in either aquifer have not been affected by the drilling, pumping and injection activities that were taking place, or by the precipitation increase observed during the project. In terms of groundwater composition, the Port Campbell Limestone groundwater is fresh (electrical conductivity = 801-3900 ?S/cm), cool (temperature = 12.9-22.5 °C), and near-neutral (pH 6.62-7.45), whilst the Dilwyn Formation groundwater is fresher (electrical conductivity 505-1473 ?S/cm), warmer (temperature = 42.5-48.5 °C), and more alkaline (pH 7.43-9.35). Evapotranspiration and carbonate dissolution control the composition of the groundwaters. Comparing the chemical and isotopic composition of the groundwaters collected before, during and after injection shows either no sign of statistically significant changes or, where they are statistically significant, changes that are generally opposite those expected if CO2 addition had taken place. The monitoring program demonstrates that the physical and chemical integrity of the groundwater resources has been preserved in the area.

No abstract available

High-CO2 gas fields serve as important analogues for understanding various processes related to CO2 injection and storage. The chemical signatures, both within the fluids and the solid phases, are especially useful for elucidating preferred gas migration pathways and also for assessing the relative importance of mineral precipitation and/or solution trapping efficiency. In this paper, we present a high resolution study focused on the Gorgon gas field and associated Rankin Trend gases on Australia's North West Shelf. The gas data we present here display clear trends for CO2 abundance (mole %) and %- C CO2 both areally and vertically. The strong spatial variation of CO2 content and %- C and the interrelationship between the two suggests that processes were active to alter the two in tandem. We propose that these variations were driven by the precipitation of a carbonate phase, namely siderite, which is observed as a common late stage mineral. This conclusion is based on Rayleigh distillation modeling together with bulk rock isotopic analyses of core, which indicates that the late stage carbonate cements are related to the CO2 in the natural gases. The results suggest that a certain amount of CO2 may be sequestered in mineral form over short migration distances of the plume.

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.

A geomechanical assessment of the Naylor Field, Otway Basin, Australia has been undertaken to investigate the possible geomechanical effects of CO2 injection and storage. The study aims to evaluate the geomechanical behaviour of the caprock/reservoir system and to estimate the risk of fault reactivation. The stress regime in the onshore Victorian Otway Basin is inferred to be strike-slip if the maximum horizontal stress is calculated using frictional limits and DITF (drilling induced tensile fracture) occurrence, or normal if maximum horizontal stress is based on analysis of dipole sonic log data. The NW-SE maximum horizontal stress orientation (142 degrees N) determined from a resistivity image log is broadly consistent with previous estimates and confirms a NW-SE maximum horizontal stress orientation for the Otway Basin. An analytical geomechanical solution is used to describe stress changes in the subsurface of the Naylor Field. The computed reservoir stress path for the Naylor Field is then incorporated into fault reactivation analysis to estimate the minimum pore pressure increase required to cause fault reactivation (Pp) The highest reactivation propensity (for critically-oriented faults) ranges from an estimated pore pressure increase (Pp) of 1MPa to 15.7MPa (estimated pore pressure of 18.5-233. MPa) depending on assumptions made about maximum horizontal stress magnitude, fault strength,reservoir stress path and Biot's coefficient. The critical pore pressure changes for known faults at Naylor Field range from an estimated pore pressure increase (Pp) of 2MPa to 17MPa (estimated pore pressure of 19.5-34.5 MPa).

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 (see eCat record 83199 for full details: see link right). 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 imagery data acquired from the ROVs downward facing camera during survey GA0345/GA0346/TAN1411. For the purposes of underwater imaging, the ROV was fitted with two video channels with pan and tilt, one colour Charged Coupled Device (CCD) camera, one low-light, black and white camera, one rear camera, one zoom camera, one downward facing digital HD video/stills camera, and two downward-facing lasers for scaling. Lighting was provided by four 150 W quartz-halogen lights. The ROV was deployed in a side entry garage Tether Management System (TMS) (100 m of tether cable) from the port side of the RV Tangaroa using a Launch and Recovery System (comprising a marine crane, umbilical winch and hydraulic power pack). During a `typical' deployment, the TMS was positioned approximately 20 m above the seabed, while the ROV surveyed a pre-determined transit line below the TMS at an altitude of 0.5 to 2 m above the seabed. Eight vectorised horizontal thrusters and two vertical thrusters controlled ROV motion once away from the TMS. To correlate the position of seabed video and still images with physical features in the multibeam bathymetry, the position of the ROV was tracked using a HiPAP500 Ultra-short Baseline (USBL) acoustic tracking system. A beacon was initially attached to the ROV and on the latter half of operations to the TMS, which provided both Dynamic Positioning and ROV operators with a visual reference of the position of the TMS with respect to the ship and ROV. Video footage was transmitted in real-time via the ships network to various locations throughout the ship using the `Blue Iris' software package. Live video feed to the surface enabled science operators to monitor and broadly characterise the seabed environment and ROV operators to regulate the altitude of the TMS and ROV. High-resolution still photographs (captured opportunistically along each transect) were used in conjunction with the video footage to assist identification of biota and seabed features. Upon retrieval of the ROV, video and still images were downloaded and renamed by station and a sequential image number. In the folder 'TAN1411_ROV', still images (.jpg files) and video (AVCHD .m2ts files) are arranged by study area with sub-folders named according to mission number, station number, gear code and camera number (e.g. M2_070_ROVCAM_022 = still images acquired during ROV mission 2 at station 070). USBL files (.csv) are located in each sub-folder and provide continuous navigational information on location, time (including UTC) and depth of ROV still and video imagery. Two master .csv files are located in folder 'TAN1411_ROV'.

Identification of major hydrocarbon provinces from existing world assessments for hydrocarbon potential can be used to identify those sedimentary basins at a global level that will be highly prospective for CO2 storage. Most sedimentary basins which are minor petroleum provinces and many non-petroliferous sedimentary basins will also be prospective for CO2 storage. Accurate storage potential estimates will require that each basin be assessed individually, but many of the prospective basins may have ranges from high to low prospectivity. The degree to which geological storage of CO2 will be implemented in the future will depend on the geographical and technical relationships between emission sites and storage locations, and the economic drivers that affect the implementation for each source to sink match. CO2 storage potential is a naturally occurring resource, and like any other natural resource there will be a need to provide regional access to the better sites if the full potential of the technology is to be realized. Whilst some regions of the world have a paucity of opportunities in their immediate geographic confines, others are well endowed. Some areas whilst having good storage potential in their local region may be challenged by the enormous volume of CO2 emissions that are locally generated. Hubs which centralize the collection and transport of CO2 in a region could encourage the building of longer and larger pipelines to larger and technically more viable storage sites and so reduce costs due to economies of scale.