الملخص الإنجليزي
Green hydrogen is rapidly emerging as a sustainable energy source of global
significance. The utilization of water electrolysis for hydrogen production offers
environmental advantages and enhances energy security in various sectors, including
transportation. However, the substantial challenge lies in effectively storing the hydrogen
being produced. To address this, repurposing abandoned gas and oil reservoirs presents a
convenient option for establishing underground hydrogen storage (UHS) facilities,
capitalizing on the existing infrastructure. These reservoirs possess favorable geological
characteristics, stable caprock, and readily available surface and subsurface equipment,
making them suitable for UHS operations. The success of UHS is highly dependent on the
integrity of injection, production, and blocked wells. Inadequate integrity can result in
environmental hazards and inefficient storage practices. The cement sheath encasing the
wellbore plays a critical role in preserving well integrity by preventing hydrogen from
escaping through cracks, weak areas, or other openings that could lead to uncontrolled
emissions or contamination of surrounding formations. Furthermore, stored hydrogen can
influence the stability and rheological properties of the cement, adversely impacting the
storage process. Consequently, this research involves the experimental exposure of wet
cement to hydrogen exposure for varying durations to evaluate the effects on the
rheological, mechanical, and chemical properties of the cement. The findings indicate that
exposure to hydrogen weakens the cement's compressive strength and density, while
simultaneously increasing the viscosity of the cement slurry. XRF analysis reveals the
presence of significant amounts of Calcite and Portlandite in each sample, both before and
after exposure to hydrogen. XRD results indicate a decrease in the intensity and full width
at half-maximum (FWHM) of the calcite peak after exposure to hydrogen. On the
contrary, the FWHM and peak intensity of the portlandite phase increased following the
exposure process. The FT-IR spectra demonstrate that longer hydrogen exposure times
lead to increased water adsorption in the samples. Furthermore, there is a decreasing trend
in the peak intensity of the carbonate group with prolonged hydrogen exposure. The XPS
study reveals that longer exposure to hydrogen resulted in the formation of more calcium
hydroxide phases and the emergence of new carbon-oxygen linkages in the treated
samples. These findings suggest that hydrogen and cement undergo chemical reactions.
