Responses of Microbial Communities to Light-Hydrocarbon Microseepage and Novel Indicators for Microbial Prospecting of Oil/Gas in the Beihanzhuang Oilfield,Northern Jiangsu,China

Previous studies on microbial prospecting of oil/gas only focused on the anomalies of light hydrocarbon-oxidizing microbes as main exploratory indicators and their exploration applications. In this study, we investigated the responses of microbial communities to light-hydrocarbon microseepage in the Beihanzhuang Oilfield, eastern China using denaturing gradient gel electrophoresis (DGGE) analysis and by comparing the difference of two-type areas with high- and low-flux light-hydrocarbon seepages. The results showed that the high-flux light-hydrocarbon seepage favored the growth of Nocardioides, Aciditerrimonas, sulphate-reducing bacteria (SRBs) related to Desulfosporosinus and Desulfovibrio, and Chloroflexi bacteria (b-7), implying that their anomalies might be adopted as novel subsidiary indicators for microbial prospecting of oil/gas in the Beihanzhuang Oilfield. Based on the newly obtained results, we have proposed a general strategy for microbial prospecting of oil/gas, i.e., to determine the anomalies of light hydrocarbon-oxidizing microbes, to select subsidiary indicators for microbial prospecting of oil/gas based on an assessment of the responses of microbial communities to light-hydrocarbon microseepage, to quantitatively measure subsidiary indicators and delimit their anomalies, to comprehensively interpret all microbial anomalies, and to make a suggestion for oil/gas prospecting. This general strategy with novel indicators may provide a more comprehensive evaluation for light-hydrocarbon microseepage and the corresponding anomalies, thereby reducing the exploration risk of oil/gas.