EFFECT OF GRAPHENE OXIDE NANOSHEETS FROM GRAPHITE, PETROLEUM COKE ON CEMENT PROPERTIES

Abstract

The thickening time and strength of cement are important factors in the cementing process in the oil and gas industry. When the cement slurry hardens rapidly, it thickens before reaching the target.  In addition, strong cement withstands the pressure of casing and formation. Additives are commonly used to enhance the cement's thickening time and strength. GONs have attracted attention as promising additives for cement. GONs were synthesized from graphite and petroleum coke using the liquid mechanical exfoliation method. FTIR spectroscopy revealed that the synthesized samples contain C–H, C=O, and O–H functional groups, and UV-Vis spectrometry showed absorbance at wavelengths of 233 and 261 nm. They were added to the cement at different concentrations (0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%) to investigate their effect on the cement thickening time and strength. The thickening time of the samples increased with GONs concentration; the samples containing 0.06% GONs exhibited a maximum thickening time of 155.52 min. In addition, the compressive strength and shear bond strength of the samples increased linearly with GONs concentration, reached a maximum at a GONs concentration of 0.05% (32.78 and 6.21 MPa, respectively), and decreased with further addition of GONs. SEM revealed 1.5-3.8 μm cracks in the cement without GONs, where the sample with 0.05% GONs exhibited very small cracks approximately 0.4-1.0 μm.  X-ray diffraction analysis showed that the cement with GONs contained plazolite, resulting in a high-strength, dense, and strong cement matrix. These results demonstrate that GONs effectively improve cement thickening time and strength.