Practical use of new microbiology tools in oil production

The features and benefits of applying new microbiology tools to two situations often encountered in offshore oil production in the North Sea are presented. These new tools, i.e., FISH, Quantitative Polymerase Chain Reaction (qPCR), and Denaturant Gradient Gel Electrophoresis (DGGE), give improved information compared to cultivation-based techniques. The two case studies include monitoring bacterial populations with molecular tools using nitrate injection on the Halfdan water injection system and the use of bacterial fingerprinting to identify the most probable corrosion process in scale samples. For the first case study, the FISH technique measures at least 100 times greater counts than obtained with the MPN technique. Molecular techniques can be applied much faster (typically within a few days) compared to traditional MPN techniques with a 30 days incubation time. This results in a potentially faster response time to maltreatments. For the second case study, the semi-quantitative PCR showed that scale deposits contain higher concentrations of sulfate reducing bacteria (SRB), as compared to produced water samples. The DGGE results showed that the majority of the scale community consisted of SRB and methanogenic bacteria, which are all potentially causing microbiologically influenced corrosion.