B Arun & Peter Gorman of 3M India Limited write about a new technology for detecting these corrosive organisms which can damage oil & gas and cooling tower operations.
The 3M Rapid Sulfate Reducing Bacteria (SRB) Detection Pouch is a self-contained, thin-film culture device designed for fast and easy testing of water in oil and gas and industrial water operations. It is used to quickly detect harmful bacteria that can cause microbiologically-influenced corrosion (MIC) in critical assets and infrastructure.
SRBs and conventional detection methods
SRBs are a class of anaerobic microorganisms that produce hydrogen sulfide from sulfate and commonly live in industrial water systems associated with oil and gas operations or cooling towers. The presence of SRBs is commonly associated with an increased risk of MIC. If SRB levels are not routinely monitored and kept in control or eliminated through treatment, they can pose a serious corrosion threat to critical assets and infrastructure. At high levels, SRBs can sour a reservoir, requiring expensive remediation efforts.
Water systems require constant monitoring to identify the concentration of problematic bacteria, such as SRB. This can be done through total bacterial count, such as ATP monitoring. While this data can be obtained quickly, it can lead to over- or undertreatment of the well, depending on how accurate the assumption is of the SRB concentration relative to the total bacterial concentration. Alternatively, growth-based methods, such as dilution bottles, provide a concentration of the target bacterial types, but take up to 28 days (per NACE standard) to provide a quantitative result.
New test for SRBs
A new microbial detection test utilizing a modified Postgate-B media and 3M laminated films has been designed to promote rapid detection and quantification of SRBs. By utilizing growth-based methods with a time-based quantitation, 3M Rapid SRB Detection pouches provide quantitative results typically within two days. It is easy to transport, does not involve fragile components, and is sealed, reducing potential leaking or contamination.
3M Rapid SRB Detection Pouches are designed for use in routine monitoring of water systems where corrosion or souring is a concern, such as in oil and gas produced water or cooling towers. After a water sample has been collected, a 3M Rapid SRB Detection Pouch would be inoculated with the sample. After inoculation, pouches are incubated.
A positive result is indicated by visual darkening of the pouch. As SRBs produce hydrogen sulfide, a precipitate is formed inside the pouch to cause this darkening. Depending on the level of darkening, the quantitation of SRB can be determined in units of Colony Forming Units per milliliter.