Waste to a commodity: the utilization of waste cooking oil for the formulation of oil-based drilling mud with H₂S scavenging capability bestowed by the incorporation of ZIF-67

Exposure to hydrogen sulfide (H2S) can result in severe health and safety issues for workers and the drilling structures, leading to significant economic burden. It is crucial to implement measures to control and mitigate the risks of H2S exposure and remove it in-situ during drilling operations. Additionally, drilling operations can be made more environmentally friendly and sustainable with the utilization of less toxic oils, such as vegetable oils, to formulate oil-based fluids instead of the highly toxic conventional diesel and mineral oils currently being utilized. Furthermore, the utilization of waste cooking oils would transfer this waste into a valuable commodity. Herein, Zeolitic Imidazolate Framework-67 (ZIF-67) NPs were used as additives to enhance the H2S scavenging capacity of an oil-based drilling fluid formulated with eco-friendly waste vegetable oil as the base fluid. The ZIF-67 NPs were synthesized and characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and the nitrogen (N-2) sorption isotherms techniques. The influence of the ZIF-67 NPs on the H2S scavenging capacity and drilling fluid viscosity was evaluated and compared to the base mud in the absence of ZIF-67 NPs. The results obtained from this study indicate that the incorporation of ZIF-67 NPs significantly enhanced the H2S scavenging capacity of the drilling fluid. The breakthrough capacity of the drilling fluid was improved by almost 140% with the addition of the ZIF-67 NPs. Furthermore, the plastic and apparent viscosities of the drilling fluid were not adversely compromised by the incorporation of the ZIF-67 NPs, indicating that these nanoparticles do not affect the fluid flow characteristics. The incorporation of ZIF-67 NPs as an H2S scavenger in drilling fluids could be a potential solution to mitigate the risks of H2S exposure during oil and gas drilling operations. Additionally, the utilization of waste cooking oils as the base fluid in drilling formulations could bring multiple economic and environmental benefits. This study provides a valuable contribution to the development of effective strategies for controlling and mitigating the hazards and environmental impacts associated with drilling operations.