Abstract

Mercaptan scavenger is a key chemical additive used in upstream oil & gas production to control mercaptan compounds (R–SH) that cause strong odor, equipment corrosion and product non-compliance. This paper summarizes typical application scenarios, reaction mechanisms, safety precautions and field application methods of mercaptan scavengers in oil and gas fields.

1 Application Scenarios

In oil and gas fields, mercaptan scavengers are widely applied in wellhead gathering, separation, transportation, storage and produced water systems. At the wellhead and gathering lines, they are injected to reduce mercaptans in crude oil, associated gas and condensate, so as to suppress odor and reduce pipeline corrosion. In production separators, scrubbers and process vessels, scavengers eliminate mercaptans in gas and liquid phases to protect downstream facilities. They are also used in transmission pipelines and storage tanks to stabilize product quality and control vent odor. In produced water treatment and reinjection systems, mercaptan scavengers reduce odor and sulfide-related corrosion to ensure stable operation of water disposal systems.

2 Technical Mechanism

Mercaptan scavengers achieve removal effect through irreversible chemical reaction with R–SH groups, converting corrosive and odorous mercaptans into stable, odorless and low-corrosive products. Triazine-based scavengers react with mercaptans under alkaline conditions to form water-soluble stable adducts, featuring high reaction speed and high efficiency. Aldehyde-based scavengers react with mercaptans through condensation to generate non-volatile and stable substances, with low fouling tendency. Metal-catalyzed or oxidizing scavengers oxidize mercaptans into disulfides (RSSR), which are odorless and basically non-corrosive, suitable for both gas and liquid treatment.

3 Safety Precautions

During storage and use, mercaptan scavengers shall be kept away from acids, oxidizers and incompatible chemicals to avoid hazardous reactions. Operators must wear chemical protective gloves, goggles and protective clothing to prevent skin or eye contact. Operation should be carried out in well-ventilated areas to avoid inhalation of vapor or mist. The products shall be stored in a cool, dry and ventilated warehouse, away from heat, sparks and open flames. In case of leakage, the spilled area shall be enclosed and absorbed with inert materials, and it is prohibited to discharge into water bodies or sewers. Compatibility with carbon steel, seals and gaskets shall be verified before application to prevent material failure.

4 Application Method

The main application methods include continuous injection and batch treatment. Continuous injection is the most commonly used in field operation: the agent is injected into pipelines, separators or gathering headers at a stable rate through a metering pump to achieve real-time removal. Batch treatment is suitable for tanks, tankers and fixed vessels, in which the agent is added according to the volume and mercaptan content. The dosage is usually determined by the concentration of mercaptans, ranging from hundreds to thousands of ppm. The injection point should be selected at the position with sufficient turbulence to ensure full mixing. After application, the outlet mercaptan content, odor, pH value and corrosion status shall be monitored regularly to adjust the dosage in time.