Spacer Fluids for Use With Rock-Based Geopolymer

Abstract

Developing a spacer fluid compatible with geopolymers and capable of facilitating effective mud displacement becomes imperative when considering the utilization of geopolymers as a complete substitute for cement in oil and gas well cementing. Drilling fluid contamination can impair the properties of geopolymer essential for zonal isolation. This study aims to design a spacer fluid tailored for geopolymer by first adjusting its rheological properties using rheology additives such as xanthan gum (XG), polyanionic cellulose (PAC), and bentonite to maintain viscosity hierarchy and aid in better mud removal. Followingly, the surfactant content in the spacer is adjusted to ensure its ability to clean the static mud layer on the surfaces and water-wet them, ultimately improving the geopolymer bonding. Lastly, the degree of compatibility of the optimized spacer and geopolymer was determined by examining the rheological properties, and compressive and tensile strength of the geopolymer when intermixing happens. These two fluids showed rheological compatibility based on the calculated R-index, an index frequently used in the petroleum industry for determining fluid compatibility. However, the gel strength was high for 25/75 geopolymer/spacer mixture. Solid to water and granite to ground granulated blast-furnace slag (GGBFS) ratio of the hardening spacer affected the degree of curing compatibility, aligning with the sensitivity of geopolymer to variations in GGBFS and water content. Heat evolution of the geopolymer showed that excessive water can hinder the dissolution of the aluminosilicate phase and later the geopolymerization reaction.