HYDROGEN SULPHIDE STABLIZERS
Hydrogen Sulphide Gas is contained in the crude oil as it comes from the wells. It not only has a vile odour, it’s also poisonous – it can kill you if you inhale it. And it’s corrosive. ‘Rotten eggs’ means hydrogen sulfide gas (H2S) – they share a common odour. If the crude is ‘wet’ � that is, if it contains water – the H2S and the H2O will react to form H2SO4 – sulfuric acid, a heavy oily liquid that can eat its way through a steel pipeline or storage tank.
Hydrogen sulfide has to go. The stabilization process�basically a form of partial distillation – does two jobs at the same time: it sweetens “sour” crude oil (removes the hydrogen sulfide) and reduces vapor pressure, thereby making the crude safe for shipment in tankers. Vapor pressure is exerted by light hydrocarbons, such as methane, ethane, propane, and butane, changing from liquid to gas as the pressure on the crude is lowered. If a sufficient amount of these light hydrocarbons is removed, the vapor pressure becomes satisfactory for shipment at approximately atmospheric pressure.
A hydrogen sulfide corrosion product is iron sulfide (FeS) which if accumulated on the inner pipe surface and other oilfield communications causes formation of a strong galvanic coupling iron/iron sulfide. As the FeS electrode potential is more positive than that of iron, iron sulfide serves as a cathode and the metal surface becomes an anode. Besides formation of muco polysaccharide slime by the bacteria makes FeS sediments sticky and improves its contact with the anode surface and at the same time protects SRB against unfavorable conditions. All these factors result into sharp increase of corrosion rate (2-4 times) especially that of pit corrosion.
Dew H2S scavengers can provide a cost-effective alternative to conventional gas/liquid sweetening processes such as amine units or solid dry bed processes to prevent hydrogen sulfide corrosion. For gas treating, the choice of an H2S removal process is based on economics. In those system where the level of H2S is < 500 ppm, the use of scavengers are a good economic choice. It is still technically possible to use scavenger to remove high concentrations of H2S and this may be the best choice for a short-term need especially if capital cost can be minimized through continuous injection. Dew Engineers can assist you in identifying and selecting the most cost-effective equipment and chemical for your facility, apply the scavenger treatments, and monitor the results to ensure optimum performance. Scavengers can be applied via pipeline/downhole continuous injection using an atomizer, or applied via a ‘Bubble Tower’ contactor.
High concentration of hydrogen sulfide and / or mercaptans can be neutralized by Dew hydrogen sulfide scavengers. Concentration of hydrogen sulfide scavengers is 5-10 g. per 1 g. of dissolved hydrogen sulfide. DEWTREATTM oxygen scavengers provided by Dew. Concentration is 8-12 g of the scavenger per each complete and incomplete gram of dissolved oxygen in the water.
Besides, service life of the equipment is extended due to reduction of corrosive components of oil during water removal.
You can get more detailed information about oilfield chemicals (demulsifiers, corrosion inhibitors, scale inhibitors, paraffin inhibitors, hydrogen sulfide scavengers, oxygen scavengers) provided by Dew in the ‘Products’ section.
Benefits:
- Improved environmental, health and safety compliance
- Maximized throughput while increasing production efficiency
- Improved water quality by preventing FeS generation, an agent know to cause sheen in discharged produced water
- Improved injectivity by eliminating FeS from produced water, an agent known to cause plugging
- Improved operational reliability
