Characterization of bacterial communities in high-temperature heavy oil reservoir

Many studies have focused on the microbial community of 20 °C~60 °C temperature heavy oil reservoirs. However, bacterial communities in (>80 °C) high-temperature heavy oil reservoir have not been studied. To investigate characterization of bacterial communities in a 86 °C high-temperature heavy oil reservoir in Shandong, China, bacterial communities of three production wells were investigated using the 16S rDNA clone library and 16S rDNA sequencing technology. A total of 539 sequences are drawn and assigned to 77 operational taxonomic units, which are classified as 20 genus species. The oil reservoir harbours many groups of bacteria. The stains of Thermanaeromonas are the predominant bacteria in D116 (38%) and D10 (27%) clone libraries, with the dominant bacteria of Thermacetogenium in D18 (33%) clone library, and the other thermophilic genera are closely related to Thermanaeromonas, Thermacetogenium, Petrobacter, and Bacillus, while halotolerant strains of Halanaerobium, Halomonas, Marinobacter, Martelella, Thalassospira, and Pelagibacterium are identified, which are consistent with the temperature and salinity of the oil reservoir. Pseudomonas, Marinobacter, Bacillus, Thermanaeromonas, Petrobacter, and Thermacetogenium, Thalassospira, have the potential to grow using heavy oil as carbon sources. The groups of Pelagibacterium and Halanaerobium produce byproducts (solvents, acids, and gases) to reduce viscosity of heavy oil. The results could provide basic theoretical guidance for additional oil recovery from heavy oil fields.