Oil and Gas Water Treatment During Upstream Gas Production
Chlorine dioxide (ClO2) is well-suited for upstream gas production during oil and gas operations, as well as other oil and gas water applications, and is highly effective and more sustainable than other oxidizing or non-oxidizing biocide options. Chlorine dioxide is a sustainable biocide that not only meets the legal requirements for sustainability, but also exceeds the business and market requirements for performance.
Benefits of Using Chlorine Dioxide
Chlorine dioxide is much more selective than other oxidizers and does not form chlorinated organics.
- Very rapid acting at low dosages
- Not pH dependent
- 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
Effective Microbial Control for Oil & Gas
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 micro biocidal 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 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.
Microbial Resistance in the Oil Field
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.
Corrosion and Mechanical Integrity
Inadequate microbial control can have a significant impact on downhole corrosion rates and can create both economic cost and sustainability concerns. SRBs (sulfate-reducing bacteria) are the primary cause of microbial-induced corrosion. Chlorine dioxide quickly and effectively kills SRBs and oxidizes the hydrogen sulfide (H2S) they produce, reducing the sour in the formation water that further reduces the corrosion rates. 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. It is clear the benefits of using ClO2 as a topside disinfectant in oil and gas applications are significant.
Recently published studies continue to show that ClO2 , when properly generated and used at typical 1-5 ppm residual concentrations for disinfection of frac water, has minimal impact on the corrosive erosive nature of fracturing operations. With the increase in produced water recycle for fracturing, frac iron systems are seeing higher salt concentrations and just like sea water systems, they will experience wet dry cycles that allow concentration of salts which significantly increase general corrosion and pitting. Proper use of inhibitors can minimize corrosion from low pH and salts, but not eliminate it. It can be concluded from these studies that acidic solutions are the main contributor to corrosion in frac systems followed by salt from produced water.