Waste cooking oil invert emulsion drilling mud formulation with an effective H2S scavenging performance

Abstract

Encountering hydrogen sulfide while drilling/stimulating subterranean formations is very common in upstream oil and gas industry. If not effectively scavenged in-situ, this lethal gas will escape to the surface causing serious health and safety problems and potential losses in human lives, in addition to significant economic penalties. Additionally, the release of waste cooking oils to the drainage/sewage systems will lead to some serious operational problems during the treatment of the collected sewage wastewaters. Thus, the key objective of this study is to convert the waste cooking oils from a burden into a valuable commodity via utilizing them for the formulation of invert emulsion drilling fluids. The waste cooking oil invert emulsion drilling mud was stabilized partially by rhamnolipid biosurfactant as a secondary emulsifier. The mud also contained hydrophobic zinc nanoparticles (NPs) as a weighting agent. To provide these waste cooking oil-based drilling muds with an effective H2S scavenging performance, a small quantity (1 wt%) of potassium permanganate was added. Despite the small quantity of the added scavenger, the mud formulation was able to scavenge 99.4 and 237.7 mg H2S/g scavenger at the breakthrough and saturation time, respectively. These H2S scavenged capacities demonstrate the feasibility of incorporating potassium permanganate, which is cheap and abundant material, into waste cooking oil invert emulsion drilling mud formulations. The flow behavior and the viscosity of the waste cooking oil-based mud comprising the H2S scavenger were found to be comparable to those reported in the literature for oil-based muds (OBMs) containing NPs.