Sulfate-reducing bacteria (SRB) are a major concern in the oil and gas industry with significant economic and safety implication. They are known to be major contributors to microbiologically influenced corrosion (MIC) in oil and gas production systems and associated with reservoir souring. Early detection and monitoring of SRB activities are critical for the field operations and the level of contamination by SRB species in the system is often used as one of the KPIs for system integrity management program. Unfortunately, growing the fastidious and strictly anaerobic SRB in the field continues to be challenging as they can be difficult to grow using traditional microbiological methods (e.g., anaerobic culture bottles). A new thin-film culture device has become available for the detection and enumeration of sulfate-reducing bacteria (SRB). This test provides an effective way to test samples directly at the source for a better understanding of the microbial activity in a system. The test is shelf-stable, self-contained, and provides a result in 48 hours or less, compared to the conventional serial dilution bottles which can take up to 28 days. In this paper, the thin-film culture device is compared to conventional serial dilution bottles using most probable number (MPN) theory, and applied for the biocide kill efficacy evaluation against SRB populations. The studies were completed in oilfields located in Middle East region to validate the application of the new thin-film culture device for effective field monitoring and quantification of SRB and biocide evaluation.
Sulfate-reducing bacteria (SRB) constitute a specialized group of phylogenetically diverse anaerobes that are responsible for the dissimilatory reduction of sulfate to sulfide. They are present in a variety of environments, including oil- and gas-bearing formations, soils, and domestic, industrial, and mining wastewaters (1,2). SRB are a major concern in the oil and gas industry with significant economic and safety implication. They are known to be major contributors to microbiologically influenced corrosion (MIC) in oil and gas production systems (3,4), reservoir souring and injectivity loss of water injection wells (5), and other problems of great economic impact in oil and gas industries, by producing H2S and iron sulfide (4). Early detection and monitoring of SRB activities are critical for the field operations and the SRB counts in the system are often used as one of the KPIs in the system integrity management. In addition, SRB are widely used as the major target organisms in biocide performance evaluation and monitoring. The surviving SRB after biocide exposure is determined using MPN tests as a key parameter to evaluate the biocide kill efficacy.
