Carbon Capture and Storage became of paramount importance in the global effort to reach carbon neutrality targets as it represents the most suitable technology for hard-to-abate industry emissions. One of the crucial challenges of CCS technologies is constituted by permanent CO2 placement in the selected geological storage site. To reach this target cement plays a fundamental role as it must provide good sealing between the well and the rock formations avoiding any possible leakage route.
Standard laboratory procedures, such as API Specification RP 10, are used to investigate cement performance and properties after extended CO2 exposure in pressurized autoclaves at controlled pressure and temperature conditions. At the end of the exposure period, cement properties are finally evaluated through mechanical, chemical and mineralogical tests. Unfortunately, this test configuration takes a significant amount of time to reach the first results and does not provide any dynamics evolution of the CO2 carbonation front. Consequently, an innovative setup was designed to improve the quality of the cement-fluids interaction assessment.
To better replicate downhole conditions, a cylindrical sandstone core is encapsulated by cement to represent inverted annular conditions. During a test, CO2 is radially injected through the sandstone core into the cement annulus, typically over a test duration of three months. An innovative in-situ test cell is developed that allows to retrieve real-time information about the evolution of the carbonation front from a CT-scanner, while the test is ongoing. In addition, CO2 consumption and system permeability measurement can also be measured under in-situ conditions.
The newly developed in-situ test cell enables instant evaluation of CO2 effect on cement, without compromising sample integrity. Thus, new insights into this complex behaviour of cement/CO2 interactions have been gained.
