The utilization of spent palm cooking oil for formulating oil-based drilling muds with excellent H2S scavenging capability

In this study, a spent palm cooking oil-based mud with an excellent H₂S scavenging capability induced by the inclusion of a small quantity of potassium permanganate is formulated and tested for the first time. The mud formulation, containing the spent palm oil as the continuous phase and water as the dispersed phase, respectively, was stabilized by Span 80 and rhamnolipid biosurfactant as primary and secondary emulsifiers, respectively, while hydrophobic zinc nanoparticles (NPs) were used as weighting agent. The results showed that H₂S scavenging capacity at the breakthrough time reached 182.4 g H₂S/barrel mud, which increased to 417.9 g H₂S/barrel mud at the saturation time, demonstrating the effective H₂S scavenging performance of the formulated mud. The spent palm oil-based mud (SPOBM) also showed a good flow behavior that could be well fitted using the Herschel-Bulkley and Casson models. The effect of temperature on the apparent viscosity of the SPOBM has been investigated, and the fitting of the viscosity-temperature data provided an estimate of the activation energy as 23.53 kJ/mol. The findings reported in this article reveal the feasibility of transforming the spent/waste cooking oils into a valuable commodity for formulating greener drilling fluids with acceptable rheology and excellent H₂S scavenging performance.