Chlorine dioxide (ClO2) is well suited for upstream gas production during oil and gas operations, as well as other oil and gas water applications. Chlorine dioxide is highly effective and more sustainable than other oxidizing or non-oxidizing biocide options.
Chlorine dioxide is a sustainable biocide—one that not only meets the legal requirements but also exceeds the business and market requirements for sustainability.
Chlorine dioxide is much more selective than other oxidizers and does not form halo-organics. Benefits include:
- Very rapid acting at low dosages
- Not pH dependant
- Improved cost and performance
- Easily monitored in the field with simple analytical methods and equipment
- Minimizes potential impact from undesired reactions with organics in water
There is a need for improved microbial control of the downhole environment in the oil patch. However, current non-oxidizing microbial control programs increase the risk of souring, corrosion, and reduced hydrocarbon flow rates.
Because the source of microbial contamination is diverse, it is clear that the major microbiocidal focus should be to prevent further contamination of new formations from surface operations. Therefore, for upstream gas production, it is desirable to use a rapid-acting, broad spectrum oxidizing biocide such as DuPont™ Chlorine Dioxide.
Non-oxidizing biocides have been the industry standard for years, and yet the downhole microbial concerns have worsened.
Downhole conditions strongly impact the end performance of non-oxidizing biocides. Chlorine dioxide is an innovative technology shift for antimicrobial control of upstream gas production.
Oxidizers that hit multiple targets are very rapid and effective microbial control agents. With chlorine dioxide the metabolic rate of the microbial species is vastly less important and the rate of effectiveness is considerably more uniform.
Chlorine dioxide is different from traditional oxidizers such as hypochlorite and other oxidizers that are ionized molecules in solution. Chlorine dioxide is a dissolved gas in solution. Therefore it easily penetrates the microbial cell wall via diffusion and performs its oxidative function on the metabolic biochemical components of the microbe.
Inadequate microbial control can have a significant impact on downhole corrosion rates and can create both economic cost and sustainability concerns. SRBs are the primary cause of microbial-induced corrosion. Chlorine dioxide quickly and effectively kills SRBs and oxidizes the H2S they produce, reducing the sour in the formation water which further reduces the corrosion rates. The chlorine dioxide at typical dose levels ultimately reacts to form sodium chloride at levels that are insignificant when compared to the natural salt levels found downhole.
Because its oxidation potential is much lower than chlorine, peroxide, or ozone, and it does not need an extreme pH level to be an effective oxidant, use of chlorine dioxide results in lower corrosivity. Oxidizers can be used to provide passivation of metal surfaces. Short-term exposure of ferrous metal to oxidizers can induce an oxide film which helps the metal resist further surface corrosion. The rapid-acting oxidative chemistry of chlorine dioxide with ferrous metals (even at low dosages, low residuals and short contact times) suggests that it may aid in passivating ferrous metal surfaces.