Application of sustainable saffron purple petals as an eco-friendly green additive for drilling fluids: A rheological, filtration, morphological, and corrosion inhibition study

Abstract

In this study, effects of dried saffron purple petals (SPP) powder were examined on the rheological, fluid loss, and corrosion inhibition properties of bentonite-based drilling fluids. Drilling fluids containing different amounts of the SPP powder were prepared and their rheological behavior was investigated via the rotary viscometry and rheometric mechanical spectroscopy (RMS). Rotary viscometer results were fitted with Power-law, Bingham plastic, and Herschel-Bulkley models and the obtained data were compared with that of the base mud. All models fitted the rotary viscometer data with the determination coefficients higher than 0.93. The presence of 3 wt% of the SSP in the fluid significantly improved the fluid’s yield stress and consistency index by 223.3% and 94.4%, respectively compared to those of the base mud. The filtration performance and cake formation results confirmed a 45% enhancement in the permeation barrier behavior of the fluid containing 3 wt% SPP powder. Electrochemical impedance measurements illustrated that the total impedance of the mild steel increase from 299 to 39,800 Ω cm2 in the presence of 3 wt% SPP powder compared to the control sample. Additionally, potentiodynamic polarization plots indicated a mixed-type inhibition mechanism for the SPP powder with the corrosion rate of 0.004 mm year−1 and inhibition efficiency of 96.5% in the presence of 3 wt% SPP powder. The morphology of mild steel plates immersed in SPP filled fluids demonstrated the formation of corrosion inhibitive layers on the metallic surface, which hindered the anodic and cathodic reactions while a considerable amount of rusts and corrosion products formed for the plate immersed in the base mud. Furthermore, having SPP as an organic green additive would leave no damaging effects on the surrounding environment and ecosystem.