There is growing awareness in completions for the requirement of long-term protection or extended coverage biocides. A “preservative biocide” is often recommended but not fully understood. Think of what preserving means; to maintain something in its existing state. That means adding a preservative biocide to an existing microbial population may not do much in the way of killing them, but likely does really well at preventing further growth. That’s why preservative biocides function best when used with a fast-acting biocide. One knocks them down, the other keeps them down. Now, don’t mistake what biocides fit into that “preservative” category. There is a middle ground of reactivity and persistency. A chemistry like bronopol is a balanced biocide neither fitting into fast acting or preservative criteria, that still provides kill and control. Make sure you are looking at these parameters for your application and what combination or chemistry would work best for the conditions and environment its being applied in.
– Virginia Wornstaff, Chief Technology Officer