Saline aquifer CO2 storage and trapping
Saline aquifers provide opportunities for greater CO2 storage with the CO2 being trapped permenantly by residual trapping
Residual saturation and dissolution trapping test
A single-well injection test methodology was developed to obtain field scale estimates of residual and dissolved CO2.
This methodology can be used for site appraisal before large scale injection for both CO2 storage and enhanced oil recovery projects
Limiting injected CO2 mobility
The project aims to provide a set of performance-based protocols for defining site closure and liability transfer, and provide solutions to best utilise geological heterogeneity and secondary trapping for project risk reduction and storage optimization.
Residual saturation and dissolution trapping test
A single-well injection test methodology was developed to obtain field scale estimates of residual and dissolved CO2.
This methodology can be used for site appraisal before large scale injection for both CO2 storage and enhanced oil recovery projects.
Rationale
The physical structure of a storage formation involves a porous and permeable reservoir rock often overlaid by an impermeable layer called cap rock. In addition to structural trapping underneath the cap rock, there are two further mechanisms that play integral roles in permanently storing CO2 in underground reservoirs. These are residual and dissolution trapping:
- Residual trapping occurs when CO2 saturation in the pore space is less than residual gas saturation (sgr). Sgr is the minimum required saturation of the injected CO2 to be mobile. The residually trapped CO2 will be permanently stored in the reservoir. The video below shows how a bubble of injected CO2 can be trapped in pore space.
- Dissolution trapping occurs when super critical CO2 dissolves into formation water.
The research project
A single-well injection test methodology was developed by CO2CRC’s research partners Lawrence Berkeley National Laboratory and CSIRO to obtain field scale estimates of residual and dissolved CO2.
The method was developed through field trials at CO2CRC’s Otway International Test Centre. The whole project involved the injection of approximately 150 tonnes of pure CO2 into a single-well as well as approximately 450 tonnes of CO2 saturated formation water, intended to saturate the formation water with CO2.
A variety of tests for measuring the residual CO2 saturation and dissolution rate in the formation water were applied including:
- Pressure measurement
- Thermal testing
- Noble gas tracing
- Dissolution testing
- Pulsed neutron logging
- Core testing
- Oxygen isotope analysis
Results & outcomes
Demonstrated that each method provides a different depth of analysis, with both advantages and disadvantages.
Developed new methods to measure residual and dissolved CO2 storage capacity within a formation.
Verified residual trapping and dissolution as storage mechanisms.
Revised concepts on residual and dissolution trapping
The methodology developed by CO2CRC can be used and built upon for industrial scale CCUS and EOR projects.
It allows for a more representative prediction and assessment of residual and dissolved CO2 at the reservoir scale than at laboratory scale.
Publications
Haese, R, LaForce. T, Boreham C, Ennis-King J., Freifeld, B., Paterson L., Schacht U.(2013) Determining residual CO2 saturation through a dissolution test – Results from a CO2CRC field experiment; Energy Procedia 37, 5379-5386
Paterson, L, Boreham C, Bunch, M, Dance, T, Ennis-King, J, Freifeld, B, Haese, R, Jenkins, C, LaForce, T, Raab, M, Singh, R, Stalker, L and Zhang. Y (2013) Overview of the CO2CRC Otway residual saturation and dissolution test, Energy Procedia 37, 6140-6148.
La Force T, Ennis-King. J, Boreham C and Paterson, L; (2013) Residual CO2 saturation estimate using noble gas tracers in a single well field test: the CO2CRC Otway Project. International Journal of Greenhouse Gas Control, , Vol 26, pp. 9-21
Myers, M, Staler, L, LaForce, T, Pejcic B, Dyt, C, Ho K-B, Ennis King J (2015) Field Measurement of residual carbon dioxide saturation using reactive ester tracers. Chemical Geology 399, 20-29.
Dance T, Paterson L; (2016) Observations of carbon dioxide saturation distribution and residual trapping using core analysis and repeat pulsed-neutron logging at the CO2CRC Otway Site; International Journal of Greenhouse Gas Control, 47, 210-220.
Serno, S, Johnson, G, LaForce, T, Ennis-King, J, Haese, R, Boreham, C, Paterson, L Freifeld B, Cook, P, Kirste, D (2016) Using oxygen isotopes to quantitatively assess residual CO2 saturation during the CO2CRC Otway 2B extension residual saturation test, International Journal of Greenhouse Gas Control, vol 52, pp. 73
Ennis-King, J, LaForce T, Paterson L, Black J, Vu H, Haese R, Sernod, S. Gilfilland , S, Johnson G, Freifeld B, , Singh R. (2017) Stepping into the same river twice: field evidence for the repeatability of a CO2 injection test; Energy Procedia, 114 2760-2771
Zhang, Y., Freifeld, B., Finsterle, S., Leahy, M., Ennis-King, J., Paterson, L., Dance, T., (2011) Single-well experimental design for studying residual trapping of supercritical carbon dioxide. International Journal of Greenhouse Gas Control 5, 88-98.
Fine-scale geological heterogeneity and secondary trapping in limiting injected CO2 mobility
The goal of the project is to obtain a unique dataset to quantify the role of fine-scale geological heterogeneity and secondary trapping in limiting injected CO2 mobility
Acquire a ‘benchmark’ dataset of CO2 saturation and fluid chemistry during plume migration and trapping within a saline formation;
Investigate the role of fine-scale heterogeneity on CO2 flow dynamics and capillary and dissolution trapping;
Validate and refine an advanced reservoir characterisation and modelling workflow to predict CO2 migration and trapping along the plume migration path;
Provide a set of performance-based protocols for defining site closure and liability transfer, and provide solutions to best utilise geological heterogeneity and secondary trapping for project risk reduction and storage optimization.
Rationale
A critical element in commercially-efficient and regulatory-compliant CO2 storage, is reliable CO2 migration and trapping prediction.
Current predictive models can have inaccuracies or uncertainties in CO2 plume distribution and trapping, due to inadequately understood effects of heterogeneity.
This creates difficulties for investment decision-making and regulatory approve for CO2 storage project operation and closure.
Solution
A new CO2 injection operation though a purpose-drilled measurement and sampling well will be conducted to obtain high resolution, repeat saturation measurements and fluid data.
This aims to quantitatively constrain CO2 flow dynamics and validate an improved fine-scale modelling capability to represent trapping processes at a resolution that will materially increase the level of confidence for stakeholders.
This benchmark data set, in combination with state-of-the art modelling and interpretation will improve the reliability of the predictive modelling and therefore the cost of permitting, monitoring and site closure.