The Effects of Dissolved Sodium Chloride (NaCl) on Well Injectivity during CO2 Storage into Saline Aquifers

Abstract

Among different options proposed for carbon dioxide (CO₂) storage and sequestration, saline formations seem promising due to their wide availability and potentially large storage capability. As supercritical (SC) CO₂ is injected into the formation, a variety of coupled processes take place. Halite precipitation requires particular interest due to its potentially significant impact on permeability impairment, and thus reduction of injectivity in the near well bore region. The selected candidate for carbon dioxide (CO₂) storage should meet the technical requirements of sealing integrity, storage capacity (potential) and containment. After the commencement of carbon dioxide (CO₂) injection into high salinity formations, formation-dry-out due to salt precipitation in the near wellbore will take place and this causes permeability and injectivity reduction. This work focuses on experimental work. The experimental work investigations studied the effectiveness dilution of high sodium chloride (NaCl) solutions with sea water and its contribution in improving the injectivity. After saturating the sandstone core samples with different brine solutions, linear core flow tests using nitrogen gas (N₂) were carried out. The saturated samples in diluted solutions for castlegate sandstone sample showed increase in the flow rate from 4 L/min at 50 psi to 5 L/min at the same pressure, and this indicates that the injectivity would be increased. Halite precipitation requires particular interest due to its potentially significant impact on permeability impairment, and thus reduction of injectivity in the near well bore region.

Keywords: CO₂ storage, seawater, CO₂/brine/rock, salinity, CO₂ injectivity