An experimental study of the effect of CO2 rich brine on artificially fractured well-cement

The performance of structural seals overlying reservoirs targeted for CO2 storage relies upon the integrity of well-bore cements, which will be affected by interactions with CO2. Microfractures within the well-bore cement may lead to seepage of CO2 to the surface and/or fresh water aquifers. Thus, understanding CO2-rich brine induced changes to the imperfections in cement matrix is vital for safe and effective implementation of this new technology named Carbon Capture Utilization and Storage (CCUS). This paper presents an experimental study that depicts the changes of the cement internal structure due to interaction with acidic brine through a system of artificial fractures within the cement matrix during 100 days flow through experiments. Helical computerized axial tomography and high resolution micro-computed tomography were used to visualize several sub-volumes of flow-through cores. Furthermore, a complementary high-resolution surface profilometry allowed quantification of changes of the roughness of fracture walls and their impact on the fracture aperture.