Dissolved hydrogen sulfide in oilfield water or mixed production can cause a multitude of issues. While H2S can be efficiently scavenged in the gas phase with triazine or amine towers, dissolved sulfide in the water phase can be more challenging to remove, especially as the concentration of sulfide approaches parts per million (ppm) level. Using triazines is an option to scavenge dissolved sulfide but necessitates using large volumes of chemical, requiring high treatment rates, and potentially introducing new issues such as scaling due to pH increase.
Acrolein is an effective oil and water-soluble sulfide scavenger most commonly used in batches of surface vessels or in downhole applications.1,2 It has also been used in North America via continuous application to scavenge low levels of H2S in both produced water and mixed phase production with few observed downstream side effects. This paper discusses historical usage of acrolein as well as recent novel applications showing marked performance benefit when compared to triazine products.
Acrolein, or 2-propenal, is a small unsaturated aldehyde with the chemical formula C3H4O. It is a liquid at room temperature and has a number of uses for oilfield and agricultural applications. This paper discusses the use of acrolein for control of dissolved sulfide in oilfield fluids, both produced water and mixed production. Acrolein is typically sold as a 95% active product with the remainder containing a hydroquinone stabilizer and residual water.
Hydrogen sulfide, or H2S, causes numerous issues in oilfield production. Along with its toxicity, H2S causes corrosion and generates iron sulfide. Iron sulfide will cause under deposit corrosion, can plug/damage equipment such as downhole pumps and filters, causes contamination of vessels and separation issues from where emulsion pads are formed. In some cases, H2S can cause system specific issues, such as incompatibility with polymer flood makeup fluid, discussed in this paper.
Acrolein offers advantages to commonly used sulfide scavengers such as triazines - it is both oil and water soluble with scavenging occurring in both phases, its byproduct has not been shown to cause further system issues and its treat rate remains consistently low even in systems with low (but still problematic) levels of dissolved sulfide.
