For the past forty years, the oil industry has relied on two recommended standard practices (API RP-38
and NACE TM0194), which provide guidance on how field samples should be collected, analysed and
results interpreted. Both documents highlight the enumeration of viable bacteria by culture techniques
as the standard method for routine monitoring and anomaly investigation. API RP-38 has now been
withdrawn. Within the appendices of TM0194 the possible availability of molecular microbiology
techniques is mentioned, but no detailed guidance or standard method for the application of any of the
molecular tools is currently available. As the application of molecular tools in environmental
microbiology is developing rapidly, it is clear that a wide range of analyses are now available as
potential tools to at last reveal ‘mysteries’ such as the complex metabolic processes causing the
problems of microbial influenced corrosion (MIC), persistence in the presence of biocides and the
souring of reservoirs during seawater flooding. However, these methods must be applied with caution.
Whilst they undoubtedly offer the potential of huge strides forward in our understanding of oil field
bacteria communities, there are no ‘off the shelf’ solutions and standardised methods will ultimately be
required if comparative data are to be generated across the industry. This paper presents a summary
of the benefits and drawbacks of some of the most commonly quoted molecular microbiology
techniques together (where available) with examples of their application to field samples.