Expanding the microbial monitoring toolkit: Evaluation of traditional and molecular monitoring methods

Abstract

Evaluation of microbial populations in oilfield systems is critical to understand the risk of microbiologically influenced corrosion, reservoir and surface souring (hydrogen sulfide production), and biofouling. Although traditional culture based methods have dominated oilfield microbial monitoring for years, use of molecular tools is becoming more common for both field and laboratory evaluations. The implementation of these additional tools is in response to some of the disadvantages of culture-based methods such as long incubation times and underestimation of actual microbial populations. The current work provides a direct comparison of culture-based methods (serial dilution for sulfate reducing, acid producing, and general heterotrophic bacteria) with molecular methods including adenosine triphosphate (ATP) and adenosine monophosphate (AMP) quantification and quantitative polymerase chain reaction (qPCR). The results demonstrate that these technologies provide nearly identical results in untreated samples with known culturable organisms, but show some differences when used in the context of a planktonic kill study. The pros and cons of each technology were addressed with respect to their use in field monitoring, laboratory monitoring, and microbial kill studies. The authors found that none of the technologies described in this work provide an all-inclusive answer, but together they provide significant insight into the microbial population in an oilfield system. In short, the authors demonstrate that it is advantageous for oilfield stakeholders to expand their microbial monitoring toolkit with these new technologies to ensure sustainable, cost-effective operation.