Harnessing zeolitic imidazolate framework-8 (ZIF-8) nanoparticles for enhancing H2S scavenging capacity of waste vegetable oil-based drilling fluids

The release of toxic hydrogen sulfide gas from subsurface oil wells during oil and gas drilling operations leads to serious health and safety problems for both the drilling structures and working personnel. The implementation of controls and mitigation techniques is vital to abating the high health and economic risks associated with H2S exposure. The effective removal of H2S gas in-situ during drilling operations is key to limiting these risks. On the other hand, utilizing waste cooking oils for formulating oil-based fluids will transfer these waste oils into valuable commodities, and will make the drilling operations greener and more sustainable. Thus, waste cooking oil was utilized in this study to formulate oil-based drilling mud (OBM). The mud contained zeolitic imidazolate framework-8 (ZIF-8) NPs as an emerging material with H2S scavenging capability. The synthesized ZIF-8 NPs were characterized by XRD, FT-IR, TGA, and the nitrogen (N2) sorption isotherm. The influence of the ZIF-8 NPs on the H2S scavenging capacity and viscosity of this green and sustainable OBM were investigated and compared to the base mud without ZIF-8 NPs. The incorporation of ZIF-8 NPs significantly enhanced the H2S scavenging capacity of the drilling fluid. The breakthrough and saturation capacities of the drilling fluid were enhanced by 150 and 245% with the addition of ZIF-8 NPs. The plastic and apparent viscosities exhibited similar behavior and were not compromised by the incorporation of ZIF-8 NPs.