Abstract

Cement is a major material component in the construction and sealing of hydrocarbon wells. Well leakage through cement is a problem that increases maintenance costs and poses threats to surrounding communities and the environment. This study focuses on reducing gas leakage potential and improving wellbore integrity by investigating Graphene Nano platelets (GNPs) as an additive that has the potential to improve cement durability by modifying the microstructure of the hydration products within the cement hence increasing the mechanical properties of Portland cement. GNPs offer distinctly high aspect ratios (length to thickness) and high thermal and electrical conductivities, which help enhance many properties of the cement. Experimental tests were conducted to evaluate the effects of introducing these nanomaterials to the cement system. The experimental tests include testing the mineralogy of the new cement formulations by implementing X-ray diffraction (XRD) analysis, testing the mechanical properties of the set cement, testing the stability and rheology of the liquid slurry, and evaluating the chemical shrinkage of the cement. In addition, the effects of adding GNPs on the hydration process of the cement was studied using isothermal calorimeter. The findings of this investigation show that adding GNPs to oil well cement systems improved the mechanical properties of the cement as the compressive and tensile strength of the cement increased by 10% and 30%, respectively by adding GNPs. The XRD analysis proved that GNPs played a key role in regulating the microstructure of the hydration products. The GNPs also aided in controlling the propagation of micro cracks within the cement matrix. These results were obtained without affecting the cement stability and rheology significantly. The high surface area and aspect ratios of GNPs also played major role in reducing chemical shrinkage of the cement system. This work demonstrates that oil well cement can be enhanced dramatically by employing nanomaterials.

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