A critical assessment of H2S scavenger performance in the presence of key acidizing package additives: surfactants, iron control agents, and anti-Sludge

Hydrogen Sulfide (H₂S) is a highly toxic and corrosive gas that poses severe risks to personnel, the environment, and equipment in the oil industry. The acidizing process, commonly used to enhance oil production, often leads to the generation of H₂S due to chemical reactions with iron sulfides present in the formation. To mitigate these risks, H₂S scavengers are employed, yet their efficiency can be influenced by various additives included in the acidizing package. While the performance of H₂S scavengers in isolation is well-documented, a critical research gap exists in understanding how their efficiency is altered by the complex chemical matrix of an acidizing fluid. Real-world formulations contain multiple additives, yet the synergistic or antagonistic interactions between scavengers and common additives like surfactants, iron control agents, and anti-sludge agents remain largely unexplored. This study is the first to systematically investigate and quantify these crucial interactions, providing a practical framework for optimizing scavenger performance in field applications. To achieve this, the study utilizes a more accurate iodometric titration method, as opposed to the traditional gravimetric techniques. The key findings indicate that additive performance is highly concentration-dependent. The iron control agent EDTA was the most effective, boosting scavenger efficiency to a maximum of 93% at 1.5 vol%. Among surfactants, the cationic CTAB performed best, reaching 86% efficiency at 1.0 vol%. Notably, the anti-sludge agent DDBSA demonstrated the most complex behavior, peaking at a high efficiency of 90% at a low concentration (0.5 vol%) before sharply declining at higher concentrations, which underscores the critical importance of precise dosage optimization. The findings provide important insights that will help optimize the formulation of acidizing packages, improving both safety and efficiency.