InterPore2026

Pore-scale thermodynamics and capillary-driven salt precipitation during brine evaporation: Implications for permeability evolution

19 May 2026, 09:50

1h 30m

Poster Presentation (MS05) Physics of multiphase flow in diverse porous media Poster

Speaker

Dr Chaojie Cheng (Institute of Applied Geosciences, KIT - Karlsruhe Institute of Technology)

Description

Unsaturated gas flowing in brine-filled formations often triggers salt precipitation and permeability impairment due to brine evaporation, a phenomenon first observed in natural gas production wells [1] and recently increasingly relevant for CO2 storage in saline aquifers [2-4]. Laboratory and modeling studies have substantially advanced the understanding of salt precipitation dynamics, revealing that capillary-driven backflow promotes salt aggregation, blocking pores and leading to severe permeability decline [5, 6]. Through core-flooding experiments combined with µCT and microfluidic experiments, the micro-processes of salt precipitation influenced by CO2 phase and flow conditions (e.g., flow rate, brine salinity, and wettability) have been widely studied [7]. However, the role of temperature under isothermal gas-phase injection still remains poorly understood.
This study investigates pore-scale salt precipitation dynamics during gaseous CO2 injection at 20, 40, and 60 °C using a temperature-controlled microfluidic platform with real-time imaging. Brine evolution and salt growth were monitored throughout the experiments. Results indicate that the total salt precipitation remains nearly constant across temperatures at fixed flow rates. In contrast, elevated temperatures markedly alter salt patterns and spatial distribution, promoting polycrystalline growth at pore throats and occasional large mono-crystals within residual brine. Both mono-crystal salt and polycrystalline aggregates exist in all experimental conditions, with the enlarged areas for polycrystalline aggregates amplified by capillary-driven backflow at the elevated temperatures. These changes result in permeability impairment by more than an order of magnitude, even with a similar amount of precipitated salt.
Our findings reveal that salt-precipitation-induced permeability damage is driven not primarily by the absolute porosity reduction but by flow-path blockage, and the total precipitated salt does not directly determine impairment severity. This underscores that the localized wettability and flow velocity in the porous media govern local evaporation dynamics and the preferential locations of salt growth, which hints at why heterogeneous materials lead to more drastic and severe permeability damage and are much more vulnerable during CO2 injection [3]. These insights have direct implications for CO2 storage operation as aquifers at slightly elevated temperatures may experience greater injectivity reduction than previously anticipated, even under comparable salt precipitation volumes. Our further endeavors with single-channel microfluidic experiments and phase-field modeling simplify and constraint the boundary conditions to shed light on the interplay of micro-physical processes, including local flow velocity, wettability, and backflow dynamics.