Characterization, morphology and shear bond strength analysis of geopolymers: Implications for oil and gas well cementing applications

The aim of this paper is to present results of testing class F fly-ash and its potential application for oil and gas cementing applications. The main challenge in applications of these material is due to lack of research in understanding how these materials react in downhole conditions. Therefore, the methodology followed in this paper is based on experiments to understand geopolymer reactions with activator(s) and second compare some of their properties such as morphology and shear bond strength with Portland cement samples. Furthermore, we investigate the effects of chemical changes of alkaline activators on the shear bond and compressive strength and to analyze the microstructure and morphology of the slurry through SEM (Scan Electron Microscopy), and EDS (Energy Dispersive Spectroscopy). Experimental workflow includes testing several mix designs of geopolymers with different molarity. Observations from experiments confirmed increase in the specimen strength as the molarity increases. In addition, the analysis of the microstructure through SEM and EDS indicated that the Al and Si had considerable influence on the structure of the slurry. Further, we present results for shear bond tests conducted on two different pipe surfaces. Test results showed geopolymers have potentials to be applied for cementing pourposes with good morphology and shear bond strength Albeit, mix design plays a key role where excessive plasticizer concentration is determental to their performance. Additionally, an increase in Shear Bond Strength of fly ash-based geopolymer with a molar concentration of NaOH from 8 M to 10 M.