Insights into H2S Scavengers and Corrosion Inhibitor Interactions for Sour Crude Applications

Abstract

Abstract Hydrogen Sulfide (H2S) produces an acidic fluid that is corrosive to equipment, tubulars, and facilities generating what is called "sour corrosion". One viable option to handle this gas in processing facilities is to use H2S scavengers. The main objective of this study is to evaluate six different H2S scavengers aiming to reduce the effect of H2S gas in crude oil feeds without jeopardizing the corrosion inhibitor performance that used in Gas Oil Separation Plant (GOSP). The tested scavengers were derived from different chemical families. Some of the active compounds of these scavengers included inorganic salts, polyhydric alcohols, organic acids, chelating agents, polyols, cyclic nitrogen compounds, potassium permanganate, and zinc oxide. These scavengers underwent compatibility tests with different corrosion inhibitors using HPHT aging cell at 200°F for 24 hours. Moreover, corrosion inhibition was evaluated using low carbon sour grade steel (T-95) metal coupons at 130°F for 24 hours testing time simulating GOSP conditions. The H2S scavenging assessment was conducted using standard aqueous geochemical methods by reacting iron sulfide (FeS) with hydrochloric acid (HCl) to generate H2S. The evolved H2S was allowed to pass through a reactor vessel containing the tested scavenger. Excess or unreacted H2S that was not captured by the scavenger was gravimetrically quantified using cadmium sulfate (CdSO4) to measure scavenging efficiency. Final scavenging capacity was calculated using mass balance approach for H2S through the system. Based on the findings of this study, three chemicals emerged with acceptable scavenging capabilities and miscibility with hydrocarbon or aqueous phases. The results indicated that liquid-based scavengers had a higher scavenging capacity compared to solid scavengers. The corrosion inhibitors excellent performance for the duration of testing. The remaining scavengers did not pass the required scavenging efficiency or showed incompatibility with the carrier fluid. This paper shares the process of evaluating H2S scavengers for sour crude feed applications. It focuses on an overlooked incompatibility between H2S scavengers and corrosion inhibitors which can cause severe consequences if not taken into consideration as both additives can potentially lose their intended functionality.