Replacing Portland Cement with Granite-Based Geopolymers for Oil Well Applications; Conventional Two-Part System

Abstract

Inorganic geopolymers typically consist of aluminosilicate-rich powders and alkali silicate solutions as hardeners. When these components are mixed, geopolymers exhibit a behavior similar to that of cement. The final product leaves a significantly lower carbon footprint compared to conventional cement. This paper offers a comprehensive characterization of a granite-based geopolymer designed for oilfield applications, adhering to the standard tests specified by API RP 10B-2. It also highlights the advantages and current limitations of this innovative technology while identifying areas for further research and development. This geopolymer has been specifically engineered to completely replace Ordinary Portland Cement in well cementing applications. We conducted a series of tests, following API standards, to evaluate its fluid-state properties, including viscosity, static gel strength, thickening time, static fluid-loss, free fluid, and density. Additionally, we examined its mechanical properties after solidification, such as sonic strength development, uniaxial compressive strength, and volume change. Our analysis of the granite-based geopolymer demonstrates the effective performance of the dispersant, reducing viscosity, and enhancing mixability. We observed a brief gel transition time upon setting, and the mix exhibited slight expansion during the strength development phase. Notably, strength development remained continuous and did not plateau even after 30 days of curing. These geopolymers combine high compressive strength with exceptional flexibility. Furthermore, temperature sensitivity analysis revealed that an 8ºC increase did not affect the gelation time. This granite-based geopolymer is a cement-free system with a low calcium content, measuring less than 15% by weight. It presents a sustainable and environmentally friendly alternative for replacing Portland cement in oil wells, both during well construction and abandonment. Moreover, it proves to be an excellent choice for constructing CCUS (Carbon Capture, Utilization, and Storage) and geothermal wells.