Performance of Different H<sub>2</sub>S Scavengers in Crude Oil

The presence of H<sub>2</sub>S in petroleum compromises the integrity of industrial equipment, affects the quality of by-products, and poses environmental and occupational challenges that increase costs and operational risks. A common solution to mitigate this contaminant is the continuous injection of liquid H<sub>2</sub>S scavengers into the production stream. Most technical publications focus on H<sub>2</sub>S scavengers for gaseous hydrocarbons and aqueous fluids at temperatures below 70°C, but there are few references regarding scavenger performance in liquid organic media at temperatures above 70°C. This article presents the results of a comparative study on the H<sub>2</sub>S scavenging capacity of various concentrated active compounds and commercial products used in the petroleum industry. The methodology involves subjecting oils with different densities to a constant flow of gas with a known H<sub>2</sub>S concentration at 33.1 kPa and 130°C. The H<sub>2</sub>S concentration is measured in the gas phase using gas chromatography and in the liquid phase by potentiometric titration throughout the test period, after passing through the reaction system and before and after the introduction of a known aliquot of the H<sub>2</sub>S scavenger. The methodologies employed allow for the evaluation and comparison of the H<sub>2</sub>S scavenging capacity of the products analyzed. This enables classification according to efficiency, using tests that simulate conditions closer to field applications, with a predominantly organic environment, similar to new oil wells where the water content is less than 1 %(v/v). Among the commercial H<sub>2</sub>S scavengers evaluated, the product based on ethoxylated compounds showed the best performance, while MEA-triazine and glyoxal-based scavengers exhibited lower performance, with glyoxal being slightly more effective than MEA-triazine. The zinc carboxylate-based scavenger demonstrated the lowest performance among the products tested. The study also showed that the mass of H<sub>2</sub>S reacted is proportional to the product dosage, within the tested range of 500 mL/L to 1000 mL/L for all products. The information generated enables informed decisions regarding the best product for oil production, aiming for greater efficiency and a lower volume of injected scavenger. This approach supports operational safety, regulatory compliance, and minimal impact on oil refining stages due to residual scavengers and reaction products present in the produced oil.