Rheological and Mechanical Properties of Rock-Based Geopolymers Developed for Well Abandonment: Effect of Chemical Admixtures at Elevated Temperatures

Examination of alternative cementitious material cured under elevated temperatures is essential to qualify their applicability in field operations. Geopolymers rise as an alternative for Ordinary Portland Cement in oil and gas applications due to its lower carbon footprint and raw material availability. Using chemical admixtures is crucial to engineer geopolymer material for displacement and to maintain well integrity and zonal isolation under elevated temperature and pressure. In this study, the rheological and mechanical properties of rock-based geopolymers, developed for utilization at elevated temperatures, have been examined with the addition of chemical admixtures to test their performance under operational conditions. Neat Class-G cement, by Dyckerhoff, was used as a reference sample for comparison at elevated conditions. The effect of Zn2+, K+, Na+ and Ca2+ species was examined on geopolymer properties. Samples were cured for 1,3, and 7 days at bottomhole static conditions. Properties examined in this study include workability, fluid loss, and viscosity for slurry properties. On the other hand, sonic strength, uniaxial compressive strength, and tensile strength were examined throughout the curing periods. The obtained results exhibited an enhancement in overall properties with an increase in workability and overall strength of the material while considering the poisoning effects from the usage of Zn2+ species. It was concluded that the combination of Na+ and Ca2+compensated the poisoning effect foreseen by the addition of Zn2+ species in geopolymer systems.