Speaker
Description
Geological heterogeneities impact the timescale and distribution of capillary trapping of CO$_2$ in aquifers [1,2]. Natural capillary pressure barriers trap the non-wetting phase at saturations greater than expected from pore-scale residual trapping processes alone, potentially providing greater CO$_2$ storage capacity. Capillary heterogeneity trapping has the potential to significantly improve the security of CO$_2$ storage in underground aquifers by immobilizing a large proportion of the injected CO$_2$ [1,2], however the connection between pore-scale fluid dynamics and larger scale flow processes have yet to be properly elucidated. The dynamics of the flow through pore throats may play a significant role in geological carbon storage [3,4], particularly at the boundary between different grain sizes. However, it is heterogeneity at centimetre-scale, over many thousands of pores, that leads to the larger scale phenomena of capillary heterogeneity trapping.
In this experimental campaign, state of the art synchrotron-based X-ray micro-CT experiments at the European Synchrotron (ESRF) were performed to investigate pore-scale flow dynamics in heterogenous sandstone cores over centimetre-scale fields of view. To investigate the impact of mm-cm scale natural geological heterogeneities on fluid migration and trapping, we performed experiments on 3 different sandstone samples: Bentheimer with layers perpendicular to flow, Bentheimer with layers parallel to flow and Bunter sandstone from a UK target storage site, the Endurance field. To evaluate the rate dependency of trapping, experiments over 2 different rates were compared to explore potential trapping within a range of carbon sequestration projects.
The high energy of the ID19 beamline at ESRF allowed us to capture frontal advance and trapping dynamics at pore-scale resolution (6.5 μm) in large heterogeneous consolidated samples (6 cm). With time resolution of 3 minutes, we observed unsteady state displacements, the prevailing conditions at most storage sites [1,4]. We captured dynamically both drainage and subsequent imbibition, proceeding until the residual saturation was reached. Pore-scale trapping mechanisms were captured with a field of view over the continuum core-scale, allowing us to investigate how larger scale capillary heterogeneity trapping processes are impacted by pore-scale events. Such experimental observations resolving trapping over many pores, representative of the large-scale process, are crucial for model validation, development and ultimately storage predictions [5].
We were able to observe, at the pore-scale, the transient interaction of the fluids with different types of layered heterogeneity. The heterogeneity impacted pore-filling events, and subsequent imbibition, allowing us to quantify the path to residual trapping. Consistent with numerical simulations [2], injection rate impacted capillary trapping with lower capillary number resulting in a greater amount of capillary heterogeneity trapping. The results from this synchrotron campaign advance our understanding of the impact of heterogeneity on the dynamics of capillary trapping within CO$_2$ storage sites.
References
[1] Krevor, S. C. M., Pini, R., Li, B., & Benson, S. M. (2011). Capillary heterogeneity trapping of CO2 in a sandstone rock at reservoir conditions. Geophysical Research Letters, 38. https://doi.org/10.1029/2011GL048239
[2] Harris, C., Jackson, S. J., Benham, G. P., Krevor, S., & Muggeridge, A. H. (2021). The impact of heterogeneity on the capillary trapping of CO2 in the Captain Sandstone. International Journal of Greenhouse Gas Control, 112. https://doi.org/10.1016/j.ijggc.2021.103511
[3] Rücker, M., Berg, S., Armstrong, R. T., Georgiadis, A., Ott, H., Schwing, A., et al. (2015). From connected pathway flow to ganglion dynamics. Geophysical Research Letters, 42. https://doi.org/10.1002/2015GL064007
[4] Spurin, C., Bultreys, T., Maja, R., Garfi, G., Novak, V., Berg, S., & Blunt, M. J. (2020). Real-time imaging reveals distinct pore scale dynamics during transient and equilibrium subsurface multiphase flow. Water Resources Research, 56. https://doi.org/10.1029/2020WR028287
[5] Jackson, S. J., & Krevor, S. (2020). Small-scale capillary heterogeneity linked to rapid plume migration during CO2 storage. Geophysical Research Letters, 47. https://doi.org/10.1029/2020GL088616
| Participation | In-Person |
|---|---|
| Country | United Kingdom |
| Energy Transition Focused Abstracts | This abstract is related to Energy Transition |
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