Eddy Covariance (EC) is considered a key atmospheric technique for quantifying CO2 leakage. However the complex and localised heterogeneity of a CO2 leak above the background environmental signal violates several of the critical assumptions made when implementing the EC technique, including: - That horizontal gradients in CO2 concentration are zero. - That horizontal and vertical gradients in the covariance of CO2 and orthogonal wind directions are zero. The ability of EC measurements of CO2 flux at the surface to provide information on the location and strength of CO2 leakage from below ground stores was tested during a 144 kg/day release event (27 March - 13 June 2012) at the Ginninderra controlled release facility. We show that the direction of the leak can be ascertained with some confidence although this depends on leak strength and distance from leak. Elevated CO2 levels are seen in the direction of the leakage area, however quantifying the emissions is confounded by the potential bias within each measurement through breaching of the assumptions underpinning the EC technique. The CO2 flux due to advection of the horizontal CO2 concentration gradients, thought to be the largest component of the error with the violation of the EC technique's assumptions, has been estimated using the modelling software Windtrax. The magnitude of the CO2 flux due to advection is then compared with the measured CO2 flux measured using the EC technique, to provide an initial assessment of the suitability of the EC technique to quantifying leakage source rates. Presented at the 2013 CO2CRC Research Symposium

Hot Rocks in Australia - National Outlook Hill, A.J.1, Goldstein, B.A1 and Budd, A.R.2 goldstein.barry@saugov.sa.gov.au hill.tonyj@saugov.sa.gov.au Petroleum & Geothermal Group, PIRSA Level 6, 101 Grenfell St.Adelaide SA 50001 Anthony.Budd@ga.gov.au Onshore Energy & Minerals Division, Geoscience Australia, GPO Box 378 Canberra ACT 26012 Abstract: Evidence of climate change and knowledge of enormous hot rock resources are factors stimulating growth in geothermal energy research, including exploration, proof-of-concept appraisals, and development of demonstration pilot plant projects in Australia. In the six years since the grant of the first Geothermal Exploration Licence (GEL) in Australia, 16 companies have joined the hunt for renewable and emissions-free geothermal energy resources in 120 licence application areas covering ~ 67,000 km2 in Australia. The associated work programs correspond to an investment of $570 million, and that tally excludes deployment projects assumed in the Energy Supply Association of Australia's scenario for 6.8% (~ 5.5 GWe) of Australia's base-load power coming from geothermal resources by 2030. Australia's geothermal resources fall into two categories: hydrothermal (from relatively hot groundwater) and the hot fractured rock i.e. Enhanced Geothermal Systems (EGS). Large-scale base-load electricity generation in Australia is expected to come predominantly from Enhanced Geothermal systems. Geologic factors that determine the extent of EGS plays can be generalised as: - source rock availability, in the form of radiogenic, high heat-flow basement rocks (mostly granites); - low thermal-conductivity insulating rocks overlying the source rocks, to provide thermal traps; - the presence of permeable fabrics within insulating and basement rocks, that can be enhanced to create heat-exchange reservoirs; and - a practical depth-range, limited by drilling and completion technologies (defining a base) and necessary heat exchange efficiency (defining a top). A national EGS resource assessment and a road-map for the commercialisation of Australia's EGSs are expected to be published in 2008. The poster will provide a synopsis of investment frameworks and geothermal energy projects underway and planned in Australia.

The first large-scale projects for geological storage of carbon dioxide on the Australian mainland are likely to occur within sedimentary sequences that underlie or are within the Triassic-Cretaceous, Great Artesian Basin (GAB) aquifer sequence. Recent national1 and state2 assessments have concluded that certain deep formations within the GAB show considerable geological suitability for the storage of greenhouse gases. These same formations contain trapped methane and naturally generated CO2 stored for millions of years. In July 2010, the Queensland government released exploration permits for Greenhouse Gas Storage in the Surat and Galilee basins.An important consideration in assessing the potential economic, environmental, health and safety risks of such projects is the potential impact CO2 migrating out of storage reservoirs could have on overlying groundwater resources. The risk and impact of CO2 migrating from a greenhouse gas storage reservoir into groundwater cannot be objectively assessed without knowledge of the natural baseline characteristics of the groundwater within these systems. Due to the phase behaviour of CO2, geological storage of carbon dioxide in the supercritical state requires depths greater than 800m, but there are few hydrogeochemical studies of these deeper aquifers in the prospective storage areas. Historical hydrogeochemical data are compiled from various State and Federal Government agencies. In addition, hydrogeochemical information is compiled from thousands of petroleum well completion reports in order to obtain more information on the deeper aquifers, not typically used for agriculture or human consumption. The data are passed through a QC procedure to check for mud contamination and to ascertain whether a representative sample had been collected. The large majority of the samples proved to be contaminated but a small selection passed the QC criteria. The full dataset is available for download from GA's Virtual Dataroom. Oral presentation at "Groundwater 2010" Conference, 31 October - 4 November 2010, Canberra

Deployment of Unmanned Aerial Vehicle during surface CO2 release experiments at the Ginninderra greenhouse gas controlled release facility H. Berko (CO2CRC, Geoscience Australia), F. Poppa (The Australian National University), U. Zimmer (The Australian National University) and A. Feitz (CO2CRC, Geoscience Australia) Lagrangian stochastic (LS) forward modelling of CO2 plumes from above-surface release experiments conducted at the GA-CO2CRC Ginninderra controlled release facility demonstrated that small surface leaks are likely to disperse rapidly and unlikely to be detected at heights greater 4 m; this was verified using a rotorcraft to map out the plume. The CO2 sensing rotorcraft unmanned aerial vehicle (RUAV) developed at the Australian National University, Canberra, is equipped with a CO2 sensor, a GPS, lidar and a communication module. It was developed to detect and locate CO2 gas leaks; and estimate CO2 concentration at the emission source. The choice of a rotor-craft UAV allows slower flight speeds compared to speeds of a fixed-wing UAV; and the electric powered motor enables flight times of 12 min. In experiments conducted at the Ginninderra controlled release facility, gaseous CO2 (100 kg per day) was released from a small diffuse source located in the middle of the paddock, and the RUAV was flown repeatedly over the CO2 source at a few meters height. Meteorological parameters measured continuously at the site at the time of the flight were input in the LS model. Mapped out horizontal and vertical CO2 concentrations established the need to be close to the ground in order to detect CO2 leakage using aerial techniques. Using the rotorcraft as a mobile sensor could be an expedient mechanism to detect plumes over large areas, and would be important for early detection of CO2 leaks arising from CCS activities.

Geological storage of CO2 is a leading strategy for large-scale greenhouse gas emission mitigation. Monitoring and verification is important for assuring that CO2 storage poses minimal risk to people's health and the environment, and that it is effective at reducing anthropogenic CO2 emissions. Eddy Covariance (EC) has been proposed as a long-term monitoring solution for geological storage projects and is considered suitable for monitoring areas 1000 - 100,000 m2 in size. Eddy Covariance is a key micrometeorological technique which has traditionally been used for assessing ecosystem exchange of CO2 in a variety of natural and agricultural settings. It measures the vertical transfer of scalar variables such as CO2 via eddies from upwind of the instrumentation, and correlates the measured CO2 flux to the upwind source area based on several key assumptions. These assumptions include that the upwind source area is homogeneous, flat and uniform, which in turn requires that horizontal gradients in CO2 concentration are zero and that horizontal and vertical gradients in the covariance of CO2 concentration and orthogonal wind directions are zero. Work undertaken at the GA-CO2CRC Gininnderra controlled release facility, where CO2 is released from the shallow subsurface (at 2 m depth), suggests that CO2 leakage in the near subsurface will follow paths of least resistance up to the surface. Similar observations have been observed at the ZERT facility in Montana and CO2 Field Lab in Norway. This leads to CO2 leaks having localised, patchy surface expression, rather than a diffuse wide-scale leak which one typically expects (Lewicki et al. 2010). The implication of this is that the source area for a leak is highly inhomogeneous, meaning the magnitudes of CO2 flux values measured using EC are grossly unreliable. These limitations were discussed in Leuning et al.'s (2008) review on CCS atmospheric monitoring technologies yet are not addressed in much of the recent EC leak quantification literature. This presentation will present findings from the first subsurface release at the CO2CRC facility in Canberra (March - May 2012), where EC data was analysed for application in leak detection and quantification. The CO2 release rate was 144 kg/d. Eddy Covariance was successfully used to detect the leak by comparing CO2 fluxes in the direction of the leak to baseline wind sectors. Median CO2 fluxes in the leak direction were 9.1 µmol/m2/s, while the median background flux was 1.0 µmol/m2/s. Separate measurements taken using a soil flux meter found that the daytime background soil flux had a median flux of 1.8 µmol/m2/s but the peak soil flux over a leak was 1100 µmol/m2/s. Quantification and spatially locating the leak were attempted, but due to the problem of source area inhomogeneity, no substantive progress could be made. How an inhomogeneous source area contributes to 'lost' CO2 from the system, through advection and diffusion, will be discussed, coupled with suggestions for how these parameters can be evaluated in future experimental design. Leuning R., Etheridge D., Luhar A., and Dunse B., 2008. Atmospheric monitoring and verification technologies for CO2 sequestration. International Journal of Greenhouse Gas Control, 2(3), 401-414. Lewicki J. L., Hilley G. E., Dobeck L., and Spangler L., 2010. Dynamics of CO2 fluxes and concentrations during a shallow subsurface CO2 release. Environmental Earth Sciences, 60(2), 285-297. Presented at the 2014 Australian Earth Sciences Convention (AESC)

Monitoring is an important aspect in verifying the integrity of the geological storage of greenhouse gases. Geoscience Australia is working with CSIRO, the CO2CRC, the Australian National University, the University of Adelaide and the University of Wollongong to develop and evaluate new techniques to detect and quantify greenhouse gas emissions.

Geological storage of greenhouse gases is one approach that the Australian Government is pursuing to assist Australia, and the world, to reduce greenhouse gas emissions into the atmosphere. Understanding the geology of Australia's sedimentary basins and their potential for greenhouse gas storage is an important component of Geoscience Australia's work in supporting emission reductions.

Geoscience Australia and CO2CRC have constructed a greenhouse gas controlled release reference facility to simulate surface emissions of CO2 (and other GHG gases) from an underground slotted horizontal well into the atmosphere under controlled conditions. The facility is located in a paddock maintained by CSIRO Plant and Industry at Ginninderra, ACT. The design of the facility is modelled on the ZERT controlled release facility in Montana, which conducts experiments to develop capabilities and test techniques for detecting and monitoring CO2 leakage. The first phase of the installation is complete and has supported an above ground, point source, release experiment, utilising a liquid CO2 storage vessel (2.5 tonnes) with a vaporiser, mass flow controller unit with a capacity for 6 individual metered gas outlet streams, equipment shed and a gas cylinder cage. Phase 2 involved the installation of a shallow (2m depth) underground 120m horizontally drilled slotted well, in June 2011, intended to model a line source of CO2 leakage from a storage site. This presentation will detail the various activities involved in designing and installing the horizontal well, and designing a packer system to partition the well into six CO2 injection chambers. A trenchless drilling technique used for installing the slotted HDPE pipe into the bore hole will be described. The choice of well orientation based upon the effects of various factors such as topography, wind direction and ground water depth, will be discussed. It is envisaged that the facility will be ready for conducting sub-surface controlled release experiments during spring 2011.

CO2CRC Project 1 - Site Specific Studies for Geological Storage of carbon Dioxide Part 1: Southeast Queensland CO2 Storage Sites - Basin Desk-top, Geological Interpretation and Reservoir Simulation of Regional Model

Approximately one quarter of Australia's CO2 emissions come from southeast and central Queensland. This poster presents the geoscientific interpretations which lead to constructing a simplified 3-D model of a potential geological storage site for CO2. The Bowen Basin is located in northeast Australia, approximately 200 to 500 km from major CO2 emission hubs in southeast Queensland. The resources of the Bowen Basin include coal, oil and gas, and there are water resources within the overlying Great Artesian Basin. Defining trap integrity within the Bowen Basin is important to ensure that none of these resources are compromised. The Wunger Ridge area has been the focus of petroleum exploration for hydrocarbons. Geological, geophysical, hydrodynamic, petrological, petrophysical and seal capacity interpretations of datasets from the area were undertaken. These interpretations indicate that the Triassic fluvial - deltaic Showgrounds Sandstone is the most suitable for CO2 storage and injection as it is permeable and saturated with brackish to saline water except where hydrocarbons have accumulated. Geological profiles were developed using sequence stratigraphic concepts and combined with rock properties, measured from core, to produce simplified 3-D models with the goal of assessing parameters for CO2 injection and migration. Simulation runs using simple models, based on a coarse-scale grid, suggest that either one horizontal or two vertical wells are required to inject at the proposed rate. Geological heterogeneity increases injection pressure around the wellbore and reduces injection rates compared to homogeneous models, resulting in the need for more injection wells.