Water-Extended Low-Density Granite-Based Geopolymer for Low-Temperature Well Cementing Applications: The Impact of Precursor Selection and Particle-Size Distribution

Well cementing in areas close to the seabed remains a challenge due to unique conditions such as cold temperatures and weaker formations, leading to delayed cement hardening, extended drilling operation, and well integrity issues. Considering Portland cement’s limitations in cold areas and significant CO2 emissions through its manufacturing process, the need for more sustainable alternatives is highlighted. A low-density geopolymer through the water-extended approach was developed based on a previous study on low-temperature applications. Utilizing granite-based materials, this study optimizes the mix design by refining precursor particle sizes, using high-calcium blast furnace slag (BFS), and incorporating an amorphous potassium silicate activator. The research methodology includes sets of well cementing evaluations such as viscosity measurements, pumpability tests, and mechanical strength assessments. In addition, characterization techniques such as particle-size distribution (PSD) analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and isothermal calorimetry were used. These tests were crucial in understanding the material’s behavior under the specified application conditions. The findings reveal that the proposed geopolymer mix exhibits acceptable hardening time and mechanical strength development at lower temperatures, making it suitable for the challenging conditions of cold shallow-depth cementing. The study proves the feasibility of using high water content for geopolymers with acceptable properties and the novelty of its approach in the optimization of precursor particle sizes and the addition of higher calcium BFS. The geopolymer’s performance, even with a high water/solids ratio, highlights its versatility as a potential sustainable and efficient alternative to Portland cement.