Evaluating Diethylamine and Triethylamine as Alternative Amine-Based H₂S Scavengers for Safe and Efficient Drilling in Sour Conditions

Hydrogen sulfide (H₂S) poses significant hazards in oil and gas drilling, including corrosion of drilling equipment, environmental risks, and threats to personnel safety. Therefore, effective and prompt removal of this gas is crucial. While various scavengers are employed in the drilling operation, each has limitations related to reactivity, cost, conditions, and health and environmental concerns. Ongoing research endeavors, we seek to develop a more feasible H₂S scavenger compatible with muds. This research aimed to examine the potential of using diethylamine (DEA) and triethylamine (TEA) as scavengers for H₂S in aqueous drilling fluids. The H₂S scavenging performance was addressed by identifying the breakthrough and saturation times and capacities for each material at room temperature. The study also addressed the influences of these materials on mud rheology, alkalinity, filtration performance, and corrosion affinity, comparing them with a commercialized triazine-based scavenger. These evaluations were carried out at 120 °F. This study demonstrates that DEA and TEA are highly effective scavengers for aqueous drilling fluids. Both amines provide significant scavenging capacity and surpass commercial scavengers. They delayed the release and breakthrough of H₂S gas and improved the capacity of the mud to remove the gas by 247 and 215%, respectively, compared to 179% with the commercial scavenger. The optimal conditions for this scavenging performance typically require a basic pH range and temperatures below the normal boiling points of DEA and TEA, as they become unstable beyond these limits. This makes them effective for use in shallow formations, where H₂S is present. The examined materials did not compromise the mud’s rheology and filtering performance, meeting the required practical criteria. Furthermore, they exhibited a noncorrosive nature, with corrosion rates nearing zero. When amine-based chemicals were added, the drilling fluid’s pH readings remained over the 10-pH cutoff point for sour situations. This study provides insights into enhancing H₂S scavenging mechanisms in aqueous muds, demonstrating competent mud performance, and encouraging safe and effective drilling operations─particularly with the presence of H₂S at shallow formations.