One Step Closer to Replacing Portland Cement with Geopolymers for Oil Well Applications

Abstract

Abstract Inorganic geopolymers are typically composed of aluminosilicate-rich powders and alkali silicate solutions as hardeners. Once mixed, these geopolymers exhibit cement-like behavior. However, highly alkaline solutions raise HSE (Health, Safety, and Environment) concerns in field operations. This paper provides a comprehensive characterization of a "one-part" granite-based geopolymer for oilfield applications that eliminates the need for alkaline solutions. Exactly like to cement, only fresh water is required to mix the geopolymer. As the reference material, API neat Class G cement was used for comparison. The fluid properties in the liquid state, including viscosity, gel strength, static fluid-loss, and mechanical properties after solidification such as sonic strength development, uniaxial compressive strength, and tensile strength, were tested following API standards. The initial analysis indicated that the rock-based geopolymer may not require any dispersant if the ingredients are engineered properly. However, a limitation of the geopolymer is its short thickening time at elevated temperatures. The use of two candidate organic and inorganic retarders extended the pumping time, followed by solidification and strength development. The short-term mechanical properties of the one-part geopolymer were evaluated by curing samples under downhole condition up to 60 days, where the bottom-hole circulation temperature and the static temperatures were 50°C and 70°C, respectively. The mix design exhibits a rapid transition from gelation to hardening. The compressive strength of the solidified samples was 50% less than that of the neat Class G cement, but the material demonstrated 4 times more flexibility.