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This report details the suitability of two identified sites in the Browse Basin for the geological storage of carbon dioxide: the Carbine Ponded Turbidite and the Leveque Shelf long migration dissolution trap. Detailed site assessments were completed by undertaking detailed geophysical interpretation of the top and base of each site, combined with a comprehensive structural, stratigraphic and sedimentological analysis, in order to construct a series of static 3D reservoir models for each potential storage site. These were submitted for CO2 injection simulation in order to better estimate the potential storage capacity, the potential injectivity volumes, and identify any containment-related issues of each site. Therefore this reports aims to provide technical recommendations regarding the viability of the long-term geological storage of CO2 in the Browse Basin.

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.

A study of the potential for geological storage of CO2 in the APEC (Asia Pacific Economic Cooperation) group of countries was commissioned under the APEC Energy Working Group Project (EWG Project 06/2003). This report discusses the prospectivity for CO2 storage within the "economies" of China, Taiwan, South Korea, Indonesia, Malaysia, Thailand and Philippines. The estimated CO2 emissions (SOURCES) adjacent to the major sedimentary basins (SINKS) of this region are reported from an IEA dataset. The geology of the basins (SINKS) in this area are summarised from literature sources and their prospectivity for CO2 storage is discussed in terms of stratigraphy and "play" concepts. Geological storage is considered in terms of Deep "saline" reservoir storage, Depleted hydrocarbon field storage including EOR (Enhanced Oil recovery). Storage in coal seams including ECBM (Enhanced Coal Seam Methane) was considered by the authors to be scientifically and technically very immature. However the location of coal deposits is summarised in the report. No attempt is made to estimate storage capacity with the exception of an estimate of the hydrocarbon pore space known in each basin. Data was not available on depletion schedules of these fields but it was assumed much of this space would not be available in the required time frame. The report contains an appendix with maps, sections, facies maps and references from the literature for each basin studied.

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.

Increasing CO2 emissions resulting from the expansion of coal fired power generation capacity and other industry in Queensland suggests that a long-term high capacity storage solution is needed. Despite some relatively large distances (upwards of 500 km) between sources and sinks, a review of the Galilee Basin suggests that it may have the potential to sequester a significant amount of Queensland's stationary CO2 emissions, however a paucity of data in several significant regions do not allow this potential to be fully assessed at the present time. Sandstones with good porosity and permeability characteristics occur within several formations including the Early Permian Aramac Coal Measures, the Late Permian Colinlea Sandstone and the Triassic Clematis Sandstone. Intraformational and local seals as well as a regional seal, the Triassic Moolayember Formation and the Permian Bandanna Formation, appear sufficient although these have not been tested. Stratigraphic and residual/solution trapping are the most likely CO2 storage mechanisms, as low amplitude structures are a feature of the Galilee Basin. Most of the structures targeted by exploration companies are generally too small to store CO2 in the quantities anticipated to be emitted from potential emission nodes such as the Rockhampton-Gladstone region. Regional reconnaissance indicate small 15-20 km2 structures with a 50-125 m net sandstone section are typical for the Clematis Sandstone Formation in the south eastern area of the Galilee Basin. Covering an area of approximately 247,000 km2 and measuring around 700km north-south and 520 east-west, the Galilee Basin is a significant feature of central Queensland. Three main depocentres the Koburra Trough (east), the Lovelle Depression (west) and the Southern Galilee Basin (south) contain several hundred metres of Late Carboniferous to Middle Triassic sediments (up to 3000m, 730m, and 1400m respectively). Most of the low amplitude structures in the basin, generally trending north-easterly to north-westerly, are the result of reactivation of older basement structures in the underlying Drummond and Adavale Basins. Tectonic events were dominantly compressional resulting in uplift and erosion of parts of the basin during the Late Permian and Triassic. A regional south-westerly tilt was later imposed due to downwarping of the overlying Eromanga Basin, which is up to 1200 m thick over the Galilee strata. Sedimentation in the Galilee Basin was dominated by fluvial to lacustrine (and in part glacial) depositional systems. This resulted in a sequence of sandstones, mudstones, siltstones, coals and minor tuff in what was a relatively shallow intracratonic basin. The entire Galilee sequence is saturated with good to excellent quality fresh water in both the Permian and Triassic strata (Hawkins, unpublished) with probable recharge from the north-east into the outcropping Triassic reservoirs. Sediment composition is mixed as a result of a variety of provenances including older sedimentary rock, metasediments and other metamorphic rocks, granites, volcanics and direct volcanic input (tuffs). Climate varied from glacial to warm and humid to temperate. Forty years or more of exploration in the Galilee Basin has failed to discover any economic accumulations of hydrocarbons, despite the presence of apparently good to very good reservoirs and seals in both the Permian and Triassic sequence. Further geological study and in particular the interpretation of seismic data is required to increase the understanding and assess the quality of the basin for CO2 storage including; fully assessing reservoirs, seals and trapping mechanisms; estimating storage capacity; and addressing issues such as the presence of a potentially large fresh water resource.

A geomechanical assessment of the Naylor Field, Otway Basin has been undertaken by the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) to investigate the possible geomechanical effects of CO2 injection and storage. The study aims to: - further constrain the geomechanical model (in-situ stresses and rock strength data) developed by van Ruth and Rogers (2006), and; - evaluate the risk of fault reactivation and failure of intact rock. The stress regime in the onshore Victorian Otway Basin is: - strike-slip if maximum horizontal stress is calculated using frictional limits, and; - normal if maximum horizontal stress is calculated using the CRC-1 leak-off test. The NW-SE maximum horizontal stress orientation (142ºN) determined from a resistivity image log of the CRC-1 borehole is broadly consistent with previous estimates and verifies a NW-SE maximum horizontal stress orientation in the Otway Basin. The estimated maximum pore pressure increase (Delta-P) which can be sustained within the target reservoir (Waarre Formation Unit C) without brittle deformation (i.e. the formation of a fracture) was estimated to be 10.9 MPa using maximum horizontal stress determined by frictional limits and 14.5 MPa using maximum horizontal stress determined using CRC-1 extended leak-off test data. The maximum pore pressure increase which can be sustained in the seal (Belfast Mudstone) was estimated to be 6.3 MPa using maximum horizontal stress determined by frictional limits and 9.8 MPa using maximum horizontal stress determined using CRC-1 extended leak-off test data. The propensity for fault reactivation was calculated using the FAST (Fault Analysis Seal Technology) technique, which determines fault reactivation propensity by estimating the increase in pore pressure required to cause reactivation (Mildren et al., 2002). Fault reactivation propensity was calculated using two fault strength scenarios; cohesionless faults (C = 0; ? = 0.60) and healed faults (C = 5.4; ?= 0.78). The orientations of faults with high and low reactivation propensity are similar for healed and cohesionless faults. In addition, two methods of determining maximum horizontal stress were used; frictional limits and the CRC-1 extended leak-off test. Fault reactivation analyses differ as a result in terms of which fault orientations have high or low fault reactivation propensity. Fault reactivation propensity was evaluated for three key faults within the Naylor structure with known orientations. The fault segment with highest fault reactivation propensity in the Naylor Field is on the Naylor South Fault near the crest of the Naylor South sub-structure. Therefore, leakage of hydrocarbons from the greater Naylor structure may have occurred through past reactivation of the Naylor South Fault, thus accounting for the pre-production palaeo-column in the Naylor field. The highest reactivation propensity (for optimally-orientated faults) ranges from an estimated pore pressure increase (Delta-P) of 0.0 MPa to 28.6 MPa depending on assumptions made about maximum horizontal stress magnitude and fault strength. Nonetheless, the absolute values of Delta-P presented in this study are subject to large errors due to uncertainties in the geomechanical model. In particular, the maximum horizontal stress and rock strength are poorly constrained.

Many industries and researchers have been examining ways of substantially reducing greenhouse gas emissions. No single method is likely to be a panacea, however some options do show considerable promise. Geological sequestration is one option that utilises mature technology and has the potential to sequester large volumes of CO2. In Australia geological sequestration has been the subject of research for the last 2? years within the Australian Petroleum Cooperative Research Centre's GEODISC program. A portfolio of potential geological sequestration sites (?sinks?) has been identified across all sedimentary basins in Australia, and these have been compared with nearby known or potential CO2 emission sources. These sources have been identified by incorporating detailed analysis of the national greenhouse gas emission databases with other publicly available data, a process that resulted in recognition of eight regional emission nodes. An earlier generic economic model for geological sequestration in Australia has been updated to accommodate the changes arising from this process of ?source to sink? matching. Preliminary findings have established the relative attractiveness of potential injection sites through a ranking approach. It includes the ability to accommodate the volumes of sequesterable greenhouse gas emissions predicted for the adjacent region, the costs involved in transport, sequestration and ongoing operations, and a variety of technical geological risks. Some nodes with high volumes of emissions and low sequestration costs clearly appear to be suitable, whilst others with technical and economic issues appear to be problematic. This assessment may require further refinement once findings are completed from the GEODISC site-specific research currently underway.

The Australian Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) is planning a pilot project to inject, store, and monitor carbon dioxide in a depleted gas field (Naylor Field) in the Otway Basin, Victoria, in Southeast Australia. Approximately 100,000 tonnes of CO2 are planned to be injected over a 2 year period in a new well to be located down dip of the existing crestal well. An accurate and detailed geological assessment and characterization is essential to the selection/evaluation of any potential carbon storage site, as this provides the inputs for the reservoir models that are needed to design the monitoring and verification programs. For the proposed Otway Basin Pilot Project, the stratigraphy and structure of the Early Cretaceous Waarre Formation in the Port Campbell Embayment has been studied. Detailed geological models for reservoir simulation have been established based on geological, geophysical and history matching studies. Particular emphasis has been placed on the Early Cretaceous Waarre Formation (the main regional and proposed injection reservoir) in the Naylor Field. Uncertainties in the geological model (based on good 3D seismic but poor well data) will be ultimately minimized through the drilling and logging of a new well and the re-logging of the existing well. Prior to this, there is a need to understand the geological uncertainties as they stand, so that an effective well location and well testing program can be defined. Based on limited palynological control (from neighboring wells) the Waarre Formation is not notably time transgressive within the study area; beyond this only a broad breakdown is possible. The Waarre Formation is divisible into units A, B, C and D, A being the oldest. Only the Waarre C reservoir unit is of immediate interest. From regional work it is interpreted that the top of unit B is associated with minor erosion and incision, prior to the onset of significant growth faulting associated with continental breakup. Initial Waarre C deposition is sandy incised valley fill deposits on this eroded surface. The configuration of these basal Waarre C deposits has been seismically mapped. Core interpretation establishes that subsequent Waarre C deposition occurred on a sandy low sinuosity fluvial braid plain. study area; although there are indications that the upper Waarre C was partially eroded prior to transgression of the overlying marine Waarre D unit. The Waarre C section is characterized by clean high permeability sandstones, interpreted as abandoned channel fill ~2m thick, within which there are thin shales. These shales form the only significant flow barriers within this upper unit; and appear to comprise less than 10% of the section, but mapping their distribution is difficult. Several PETREL reservoir models were created to capture the uncertainty and potential reservoir heterogeneity of the Waarre C in the Naylor Field; key parameters (for example: porosity, permeability, channel orientation, shale content, connectivity, and gradient of the top structure) have been systematically varied to provide the most likely and extreme cases for the subsequent reservoir simulation studies. The reservoir properties have been characterized through history matching of the well-head pressure and water-cut data over the 18-month production history of the well using systematic numerical simulation approaches. The results indicate that the reservoir has an average permeability of 500-1000 mD, the original gas-water contact was at 2020 meters depth and that there was a significant aquifer support to the reservoir. This reservoir characterization and history matching study has provided additional and essential knowledge of the field and helped to constrain the injection location. The study establishes a sensible current reservoir condition, which will subsequently be used as the initial condition in the simulation of CO2 injection in the depleted gas field.

This invited contribution reviews applications of small angle neutron scattering (SANS) and small angle x-ray scattering (SAXS) to study the microstructure of sedimentary and igneous rocks in the last two decades. It is demonstrated how SANS can be used to explore the microstructure of rocks and help gain insights into internal specific surface area, porosity, pore size distribution, mercury intrusion porosimetry, compaction, subsurface generation of oil and gas, adsorption of gases, imbibition of water, distribution of crystalline precipitates and the microstructural effects of heat treatment. The article is intended to provide both a comprehensive introduction for newcomers to the subject and a reference text for those already familiar with small angle scattering techniques. Individual sections are self-contained and can be read in isolation.The article includes a review of theoretical results, worked examples, description of experimental procedures, examples of interpreted data for various types of rocks and references to original work.