EGU24-15010, updated on 09 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Impact of CO2 with impurities on integrity of wellbore cements during CCS 

Reinier van Noort1 and Gaute Svenningsen2
Reinier van Noort and Gaute Svenningsen
  • 1Institutt for Energiteknikk (IFE), Department for Reservoir Technology, Kjeller, Norway (
  • 2Institutt for Energiteknikk (IFE), Department for CorrosionTechnology, Kjeller, Norway (

CO2 injected into geological reservoirs for storage will contain a range of impurities dependent on the specifications of the transport and storage operator(s). Such impurities include inert gases such as N2 and Ar, as well as reactive components including SOx, O2, and H2S. Upon injection into a (wet) reservoir, these components will partition between the CO2-phase and the hydrous pore fluid, and some of the reactive species may introduce acidification (in addition to the acidification caused by the CO2 itself), or other chemical reactions. 

In the near-wellbore area, the partitioning impurities can potentially lead to enrichment of water-soluble impurities in the hydrous fluid and corresponding depletion of these impurities in the CO2 plume. Because of this, even low (ppm-level) concentrations of reactive impurities need to be considered with regards to their potential impact on wellbore sealant integrity. As part of the Cementegrity project, we have performed exposure experiments on five different sealant compositions; three of which are based on Ordinary Portland Cement (OPC), one is based on Calcium-Aluminate Cement (CAC) and one is a granite-based geopolymer (GP). Using a purpose-built batch-exposure system, sample cylinders were exposed to water and supercritical CO2 under simulated downhole conditions of 80°C and 8-10 MPa, for up to 16 weeks. The sealant samples were placed at two different levels in each exposure apparatus, so that samples were either exposed to wet supercritical CO2, or to CO2-saturated water. The effect of H2S in the CO2 stream was studied in a second series of experiments, where 2.2 mol% H2S was added to the CO2-phase to which the samples were exposed.

After exposure, the samples were retrieved and cross-sectioned perpendicular to the axial direction, so that the impact of exposure on sealant microstructure and composition could be studied using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). In this paper, we will focus on the different impacts of exposure conditions (wet sc. CO2 vs. CO2-saturated water) as well as the additional impact of H2S.

How to cite: van Noort, R. and Svenningsen, G.: Impact of CO2 with impurities on integrity of wellbore cements during CCS , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15010,, 2024.