IN SITU SYNCHROTRON MEASUREMENTS FOR CO2 INTERACTION WITH SUBSURFACE MATERIALS

Subsurface energy resources satisfy major component of U.S. energy needs and provide a safe and reliable storage for carbon dioxide. However, maintaining the subsurface conditions for extended time periods is a challenge. The dissolution and precipitation reactions that occur at solid-fluid (rock/mineral-fluid) interfaces under hydrothermal conditions as well as carbon sequestration need to be understood as they can affect the economic viability of sequestration. Hence, it is critical to study the interfacial interactions to understand the degradation mechanisms involved in subsurface materials.

Cements and steel casings are used to seal gas and oil well bores and with the CO₂ sequestration effort, they are expected to be keep their integrity for elongated periods of time under these conditions. The exposure to CO₂ environment causes formation of several carbonate phases that can degrade the cement/steel structures and cause leakage. This study aims to study of the corrosion of cement/steel interfaces in super critical CO₂ using a sample environment designed and built for in situ X-ray diffraction in the National Synchrotron Light Source II (NSLS II). The formation of carbonate phases at cement –fluid and cement-steel/fluid interfaces will be monitored in real time.

The sample environment will be used to expose samples to super critical CO₂ at pressures above 1100 psi and temperatures around 50°C. The reaction cell is built from hastealloy to provide corrosion resistance, while the experimental temperature and pressure are controlled with thermocouples and pressure vessel.