Geopolymers, Are They Consistent Enough for Geothermal?

Abstract

In the constantly evolving renewable energy market, there are constant efforts to ensure technological develops match the growing demand for energy. In the sector of geothermal energy, well designs much be considered for both high temperature and high pressure conditions, with some wells expected to be functional for over 50 years. This makes the understanding of the cement barrier between the casing and the environment critical, as it not only provides structural support but also prevents potential fluids communications that could be environmentally detrimental. In an effort to bring new solutions to the market, ongoing investigations into geopolymers, specifically those made using type F flay ash, are suggesting general superiority of this new class of cementing material over traditional API or Portland cement based solutions. This work aims to scrutinize these investigations by subjecting many of the geothermal cement recipes analyzed in literature to API testing standards, and recording characteristics of the samples in the same manner as normal API testing would. The testing in this work focuses on uniform testing conditions for Class F Fly ash geopolymer testing, only changing conditions to match published works which suggest improvements to UCS. Over 30 geopolymer samples are tested for times ranging 1 to 21 days, and the resultant testing of the samples yielded UCS results far more variant that classic API class G, C, or H cement, with many samples failing to show strengths superior to traditional cement classes. Further investigation of the variations suggest that not only are these variables variant across samples from the same Fly Ash source, but very with both setting environmental temperature and pH.