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Abstract
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Recent developments in nanofluids indicate that the addition of nanoparticles to water-based drilling muds can alleviate many drilling problems, including wellbore instability, lost circulation, torque and drag force, differential pipe sticking, and low drilling rates. In this study, the addition of hydrophilic Gilsonite nanoparticles (HGNs) to water-based drilling mud was investigated, and its effects upon the well-cleaning process, rheological properties, filtration loss reduction, lubricity characteristics, and, more importantly, on the differential sticking of the base fluid were evaluated. Hence, initially, the HGNs were characterized by means of Fourier transform infrared spectroscopy, the dynamic light scattering technique, as well as thermogravimetric and differential thermogravimetric analysis. The results showed that after the addition of HGNs, the rheological behavior of the base mud before the hot roll process was improved, and, interestingly, after the hot roll at 149oC and 4 h, the characteristics of the sample mud were significantly retained, compared to those of the base mud. Also, after the hot roll, the plastic viscosity (PV) improved, the yield point (YP) was remarkably maintained, and the ratio of YP/PV was enhanced. On the other hand, the American Petroleum Institute (API) filtration loss was reduced by 36%, and, additionally, after the hot roll process, the filtration loss reduction and the mud cake thickness in high-pressure high-temperature conditions diminished by 79.4% and 50%, respectively. After the hot rolling process, the lubricity coefficient and torque percentage dropped by 15% and 13.63%, respectively. Also, the HGNs reduced the differential sticking coefficient and increased the likelihood of differential sticking release of the base fluid by 61.5%.
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