CO2 injection impairment due to halite precipitation

The injection of dry supercritical CO2 into brine aquifers has the potential to dry saline formation waters, due to evaporation effects [1], leading to severe increases in salinity and salt precipitation. This can significantly impair injection rates, as has been noted in gas-storage reservoirs. [2] This is of interest for CO2 storage in saline aquifers. An injection impairment study was performed for the CO2SINK Project, a European Union research project on testing geological carbon storage near Ketzin, Germany [3]. Core flood experiments showed that halite precipitates due to brine evaporating in dry super-critical CO2. The phenomenon was studied with two research codes, TOUGH2 and a streamline-based simulator. Both codes predict substantial salt deposition close to the injection point, with associated severe injection impairment. Our simulations also suggest that simple reservoir engineering measures, such as a brief (hours) preflush with fresh water, can mitigate adverse effects.