[show abstract][hide abstract] ABSTRACT: Carbon capture and storage (CCS) is vital to reduce CO(2) emissions to the atmosphere, potentially providing 20% of the needed reductions in global emissions. Research and demonstration projects are important to increase scientific understanding of CCS, and making processes and results widely available helps to reduce public concerns, which may otherwise block this technology. The Otway Project has provided verification of the underlying science of CO(2) storage in a depleted gas field, and shows that the support of all stakeholders can be earned and retained. Quantitative verification of long-term storage has been demonstrated. A direct measurement of storage efficiency has been made, confirming that CO(2) storage in depleted gas fields can be safe and effective, and that these structures could store globally significant amounts of CO(2).
Proceedings of the National Academy of Sciences 12/2011; 109(2):E35-41. · 9.74 Impact Factor
[show abstract][hide abstract] ABSTRACT: The first stage of the CO2CRC Otway Project, located in south-eastern Australia, has stored 65,445 tonnes of CO2-rich gas in the depleted Naylor Gas Field. Comparisons have been made between simulations using the non-isothermal multi-phase flow simulator TOUGH2/EOS7C and the accumulated field data up to and beyond the end of injection. The geological models and the derived simulation models have been able to fit most of the key features of the field data, including the downhole pressure measurements and the arrival time at the observation well. When fitting to the downhole pressure only, the observed arrival time was in the range of uncertainty of the model predictions. The use of multiple geostatistical realisations of heterogeneity demonstrates the importance of capturing the range of uncertainty in the geology and the consequent scatter in forward predictions. Thus the storage of CO2 in the Naylor depleted gas field is shown to be adequately modelled by numerical simulation, and this increases confidence in the suitability of similar depleted gas fields for underground storage.
[show abstract][hide abstract] ABSTRACT: Residual trapping is one of the four trapping mechanisms that have been identified for geological CO2 storage, a means to reduce atmospheric emissions and the related impacts as a result of continued use of fossil fuels. The objective of this research is to design a single-well injection-withdrawal test to estimate residual CO2 trapping (Sgr) in brine aquifers. Due to the high cost associated with drilling to depths of potential CO2 storage site, single-well test can cost-effectively provide data sets to assess reservoir properties and reduce uncertainties in the appraisal phase for finding commercial scale storage sites. The main challenges in the design are the following: (1) It is difficult to quantify the amount that is trapped using a mass balance approach; (2) correlations among various parameters leads to a highly uncertain or non-unique Sgr estimate; and (3) the Sgr estimate could be biased due to heterogeneity of the geological medium. We have proposed our design to address each of these challenges by (1) use a detailed reservoir model to simulate the relevant physical processes in the tests; (2) perform a test sequence that yields multiple types of complementary data to constrain the estimate of Sgr; (3) remove or reduce the bias caused by the heterogeneity of the storage formation by repeating the same test under different saturation conditions. The design will be applied to a practical field test that will be carried out as part of the CO2CRC Otway Project, at Victoria Australia.
[show abstract][hide abstract] ABSTRACT: The Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) Otway Project in Australia is the first heavily monitored pilot site for CO2 storage in a depleted natural gas reservoir. With the site characterisation and risk analysis complete, the new CRC-1 injection well was drilled in April 2007. An updated static and dynamic model forecast an injected gas transit time of between 4 and 8months between CRC-1 injection and Naylor-1 observation wells. Injection began on March 18th 2008 and was halted on August 29th 2009 with 65,445 tonnes of CO2 mixed gas stored. Two pulses of tracer compounds were added to help identify the injected CO2 from other naturally occurring CO2 and to track dispersion and diffusion.Assurance monitoring included surveillance of the atmosphere, soil gas and shallow groundwater. To date, no tracer compounds have been detected above background levels in samples taken as part of the assurance monitoring system. Monitoring of the reservoir has been accomplished with a combined geophysical and geochemical approach. Formation fluids are sampled at pressure with the multilevel U-Tube system. The transient geochemistry at the observation well has: (1) recorded injected gas arrival at the Naylor-1 observation well; (2) recorded tracer compound arrival at Naylor-1; (3) shown a mixing trend between the isotopic signature of the Naylor indigenous CO2 and that of the injection supply gas; and (4) provided an estimate for the dynamic storage capacity for a portion of the Naylor reservoir. The data collected are compared with the pre-injection dynamic model forecasts and provide a means of calibration.The CO2CRC Otway Project has successfully demonstrated the storage of CO2 in a depleted gas field. Geochemical assurance monitoring and reservoir surveillance will continue post injection. Continued analysis of the data will serve to reduce uncertainty in forecasting long term fate of the injected CO2 mixed gas.
International Journal of Greenhouse Gas Control - INT J GREENH GAS CONTROL. 01/2011; 5(4):922-932.
[show abstract][hide abstract] ABSTRACT: Three of the most important challenges for the near future: maximizing oil extraction, securing fresh water supplies and mitigating climate change through Carbon Capture and Storage (CCS), require a better understanding of flow in porous media. It has been shown by Qi et al  that an optimum injection strategy for CO2 storage can result in up to 90% of the injected CO2 being trapped in the pore network of the rock during the injection phase of a CO2 storage project. When the non-wetting phase saturation increases and then decreases in the pore space, part of the non-wetting phase is trapped in pores as a residual saturation. Injection of CO2 and water in alternating cycles can be used to engineer this trapping. With time, CO2 will dissolve in the brine surrounding it and finally precipitate as carbonate. The Otway Project, taking place in the south-east of Australia and lead by the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC), is the world's largest research and geosequestration demonstration project . CO2CRC has proposed testing the concept of using residual trapping to improve storage security by using Huff and Push injections. In this case, CO2 is injected in a depleted gas reservoir together with methane. The Huff and Push injection mechanism consists of a single well which alternates injection and production. Initially, brine is injected followed by a mixture of CO2/CH4/other gases (77/20/3 mole%) followed by a shut-in period. Then, when production starts the water front should move faster towards the production well and immobilise CO2 in the micro pores of the rock. Very little production of CO2 should be observed, confirming that it has been immobilized within the formation. Traditional grid-based reservoir simulations are used to predict fluid behaviour and to design injection strategies that maximize both oil extraction and trapping of carbon dioxide in the rock formation. Unlike conventional grid-based simulations, streamline-based simulators have the advantage of solving transport equations in 1D, which decreases the CPU (Central Processing Unit) time without losing accuracy. The current in-house streamline-based simulator has been extended to include compressibility. This 3-component (hydrocarbon, carbon dioxide and brine) 2-phase (aqueous and hydrocarbon) research code allows the CO2 to dissolve in both aqueous and hydrocarbon phase, water to dissolve in the hydrocarbon phase and assumes that hydrocarbons only exist in the hydrocarbon phase. The extended compressible streamline simulator will be used to simulate Huff and Push injection in the different geological scenarios taken from the Otway Project. A detailed study will be carried out to optimise the injection scheme and understand how reservoir variability can influence CO2 trapping. Streamline simulations will be compared against commercial simulations (ECLIPSE) regarding convergence of results and simulation times. 1. R Qi, T C LaForce and M J Blunt, "Design of carbon dioxide storage in aquifers," International Journal of Greenhouse Gas Control 3 195-205 (2009). 2. Website accessed on 14th January 2010: http://www.co2crc.com.au/otway/
[show abstract][hide abstract] ABSTRACT: The objective of our research is to design a single-well injection-withdrawal test to evaluate residual phase trapping at potential CO2 geological storage sites. Given the significant depths targeted for CO2 storage and the resulting high costs associated with drilling to those depths, it is attractive to develop a single-well test that can provide data to assess reservoir properties and reduce uncertainties in the appraisal phase of site investigation. The main challenges in a single-well test design include (1) difficulty in quantifying the amount of CO2 that has dissolved into brine or migrated away from the borehole; (2) non-uniqueness and uncertainty in the estimate of the residual gas saturation (Sgr) due to correlations among various parameters; and (3) the potential biased Sgr estimate due to unaccounted heterogeneity of the geological medium. To address each of these challenges, we propose (1) to use a physical-based model to simulation test sequence and inverse modeling to analyze data information content and to quantify uncertainty; (2) to jointly use multiple data types generated from different kinds of tests to constrain the Sgr estimate; and (3) to reduce the sensitivity of the designed tests to geological heterogeneity by conducting the same test sequence in both a water-saturated system and a system with residual gas saturation. To perform the design calculation, we build a synthetic model and conduct a formal analysis for sensitivity and uncertain quantification. Both parametric uncertainty and geological uncertainty are considered in the analysis. Results show (1) uncertainty in the estimation of Sgr can be reduced by jointly using multiple data types and repeated tests; and (2) geological uncertainty is essential and needs to be accounted for in the estimation of Sgr and its uncertainty. The proposed methodology is applied to the design of a CO2 injection test at CO2CRC's Otway Project Site, Victoria, Australia.
International Journal of Greenhouse Gas Control. 01/2010;
[show abstract][hide abstract] ABSTRACT: Coal-fired power stations in Collie, Western Australia emit 10 million tonnes of CO2 per year. This study assesses the potential opportunities of geological storage of CO2 both within the Collie Basin and the onshore part of the adjacent Southern Perth Basin of Western Australia within 50 km of Collie town site through a desktop evaluation of existing data. The aquifers and coal formations within both basins have been evaluated for their suitability for storage based on geological, geographical and environmental criteria related to storage capacity, injectivity, proximity to sources of CO2, location of other natural resources and containment security. The study has concluded that there is limited scope for large-scale storage of CO2 within the Collie Basin. In addition the potential for storage within coals of either basin is not a viable solution. This assessment is based on published criteria for CO2 storage in sedimentary basins and coal-bearing formations.This study has, however, identified the Harvey Ridge, a structural high in the Southern Perth Basin, as having potential for storing a large volume of CO2 within the study area. This potential has been established through a geological and hydrodynamic assessment and a comparison with the results of a previous study of simulated injection within the strata at the nearby Cockburn 1 well to the north of the Harvey Ridge. Comparison of these two locations in terms of the thickness of strata and lithology, amongst other considerations indicates that the area has more favourable characteristics for large storage than that indicated at Cockburn 1. While this provides confidence that the Harvey Ridge would be suitable, considerable further work, however, is required to establish the Harvey Ridge as a viable geosequestration option.
Marine and Petroleum Geology 01/2009; 26(7):1255-1273. · 2.11 Impact Factor
[show abstract][hide abstract] ABSTRACT: The hydrodynamic site characterization for the CO2CRC Otway Project demonstrating geosequestration in the depleted Naylor gas field determined the pre-production Darcy-flow-velocity in the target reservoir and identified pressure decline due to regional hydrocarbon production. Wellhead pressure measurements showed the depleted reservoir to be recovering much faster than predicted by the reservoir model calibrated by the production history. To provide sufficient aquifer support to match the observed recovery, the dynamic reservoir simulation required the inclusion of a dual aquifer system. This was supported both by the interpreted hydrodynamic model and by the observation of a paleo-gas column extending below the structural spill point of the Naylor gas field.