Preprints
https://doi.org/10.5194/se-2021-114
https://doi.org/10.5194/se-2021-114

  09 Sep 2021

09 Sep 2021

Review status: this preprint is currently under review for the journal SE.

Creep of CarbFix Basalt: Influence of Rock-fluid Interaction

Tiange Xing, Hamed Ghaffari, Ulrich Mok, and Matej Pec Tiange Xing et al.
  • Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology

Abstract. Geological carbon sequestration provides permanent CO2 storage to mitigate the current high concentration of CO2 in the atmosphere. CO2 mineralization in basalts has been proven to be one of the most secure storage options. For successful implementation and future improvements of this technology, the time-dependent deformation behavior of reservoir rocks in presence of reactive fluids needs to be studied in detail. We conducted load stepping creep experiments on basalts from the CarbFix site (Iceland) under several pore fluid conditions (dry, H2O-saturated and H2O+CO2-saturated) at temperature, T≈80 °C and effective pressure, Peff = 50 MPa, during which we collected mechanical, acoustic and pore fluid chemistry data. We observed transient creep at stresses as low as 11% of the ultimate failure strength, well below the stress level at the onset of bulk dilatancy. Acoustic emissions (AEs) correlated strongly with strain accumulation, indicating that the creep deformation was a brittle process in agreement with microstructural observations. The rate and magnitude of AEs were higher in fluid-saturated experiments than in dry conditions. We infer that the predominant mechanism governing creep deformation is time- and stress-dependent sub-critical dilatant cracking. Our results suggest that the presence of aqueous fluids exerts first order control on creep deformation of basaltic rocks, while the composition of the fluids plays only a secondary role under the studied conditions.

Tiange Xing et al.

Status: open (until 23 Oct 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on se-2021-114', Philip Benson, 17 Sep 2021 reply

Tiange Xing et al.

Tiange Xing et al.

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Short summary
Geological carbon sequestration using basalts provides solution to mitigate the high CO2 concentration in the atmosphere. Due to the long timespan of the GCS, it is important to understand the long-term deformation of the reservoir rock. Here we studied the creep of basalt with fluid presence. Our results show presence of fluid weakens the rock and promotes creep, while the composition only has a secondary effect and demonstrated that the governing creep mechanism is sub-critical micro-cracking.