Aluminum-Rich Cements for High Temperature Geothermal Wells

Abstract

This paper presents results of design and evaluations of various Al-rich cements under supercritical hydrothermal and CO2 field conditions. Results of short-to-long term exposure tests up to 30 days under hydrothermal and up to 9 months under supercritical CO2 environments are reported including mechanical properties, morphological, and phase changes for calcium-aluminate cement-based blends. Performance of aluminum-rich cement formulations is compared to that of Ordinary Portland Cement (OPC) with silica blend. The results confirm that properties of the blends with lower calcium content persist under supercritical CO2, while the OPC blend undergoes severe degradation with the loss of mechanical properties. For alkali activated and chemical blends partial carbonation occurs through calcium carbonation. Electrochemical corrosion tests showed that Al-rich cement formulations can provide Ni-alloy corrosion protection under supercritical conditions. All tested calcium-aluminate-cement based blends outperformed OPC/silica under the CO2-rich well conditions.