Permeability, Porosity, and Mineral Surface Area Changes in Basalt Cores Induced by Reactive Transport of CO2-Rich Brine
Andrew J. Luhmann, Benjamin Tutolo, Brian C. Bagley, David F. Mildner, Jr. Seyfried, Martin O. Saar
Four reactive flow-through laboratory experiments (two each at 0.1 ml/min and 0.01 ml/min flow rates) at 150 °C have been conducted on intact basalt cores to assess changes in porosity, permeability, and surface area caused by CO2-rich fluid-rock interaction. Permeability decreases slightly during the lower flow rate experiments and increases during the higher flow rate experiments. There is a big difference between the two higher flow rate experiments: core permeability increases by more than one order of magnitude in one experiment and less than a factor of two in the other due to differences in preexisting flow path structure of the rock cores. X-ray computed tomography (XRCT) scans of pre- and post-experiment cores identify both mineral dissolution and secondary mineralization, with a net decrease in XRCT porosity of 0.7% - 1% for all four cores. (Ultra) small-angle neutron scattering ((U)SANS) datasets indicate an increase in both (U)SANS porosity and surface area over the 1 nm- to 10 υ-scale range in post-experiment basalt examples, with difference due to flow rate and reaction time. Still, the (U)SANS data suggest an overall preservation of the pore structure is unique in comparison to previously published basalt analyses. Together, these datasets illustrate changes in physical parameters that arise due to fluid-basalt interaction in relatively low pH environments with elevated CO2 concentration. Ultimately, alteration-induced porosity, permeability, and surface area changes may have significant implications for flow, transport, and reaction through geologic formations.
, Tutolo, B.
, Bagley, B.
, Mildner, D.
, Seyfried, J.
and Saar, M.
Permeability, Porosity, and Mineral Surface Area Changes in Basalt Cores Induced by Reactive Transport of CO<sub>2</sub>-Rich Brine, Water Resources Research, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=921041
(Accessed December 4, 2023)