Practical use of new microbiology tools in oil production

Culture-based methods of traditional microbiology applied to the microbiological processes involved in souring of oil fields and microbiologically influenced corrosion (MIC) pose a threat of yielding inadequate and contradictory results. Any cultivation step will almost certainly alter the population characteristics and thus also the results on which any evaluation will be based. The need for in situ cultivation-independent methods has over the past ten years facilitated the development of several analytical methods for determination of bacterial identity, quantity, and to some extent function, applied directly to samples of the native population. This development has so far been fairly limited regarding practical application and it has only recently been transferred to the offshore industry. In this paper, we demonstrate the features and benefits of applying these novel techniques to two situations often encountered in offshore oil production in the North Sea. The new microbiology tools are based on the detection of genetic material in bacteria. The methods include direct count of specific groups of bacteria with microscopy (e.g. FISH). Additional methods (e.g. qPCR and DGGE) are based on direct extraction of cell genetic material (DNA/RNA). The paper will briefly describe these novel molecular techniques. By documenting bacterial population shifts related to water breakthrough in a nitrate treated reservoir, we showed that key bacterial populations can be identified and thereby lead to the creation of new and strengthened surveillance strategies on souring bacteria in these systems. Also, we have shown that by applying these novel techniques to aggressive corrosion attacks, especially under deposit corrosion, molecular techniques are a powerful tool in identifying the most probable corrosion process. These examples will be described and related to the offshore operation. Special focus will be given to the use of the new and improved microbiological data in relation to designing and testing remedial actions towards oil field souring and MIC.