Abstract: By the methods of molecular biology, this paper studied the bacterial community structure in the production waters from polymer-flooded, water-flooded, and transition zone’s oil reservoirs in Daqing Oilfield of Northeast China. The total DNA was extracted from the three production waters, and the 16S rDNA clone libraries of the waters were constructed. About 200 positive clones were randomly selected from each library, and analyzed with amplified ribosomal DNA restriction analysis (ARDRA). The selected 596 positive clones were clustered into 85 operational taxonomic units (OTUs), with 28 OTUs in polymer-flooded library, 41 in water-flooded library, and 33 in transition zone’s library. Sequences analysis of the libraries showed that the dominant bacterial groups in the production waters were Acinetobacter, Arcobacter, Firmicutes, Pseudomonas, and Sulfurospirillum. Polymer-flooded sample had the simplest bacterial composition, with the dominant (85%) of Acinetobacter, and part (7%) of Pseudomonas. Water-flooded sample was also dominated by Acinetobacter (62%), while Pseudomonas and Sulfurospirillum occupied 20% and 6% of the total, respectively. Different from the former two, the transition zone’s sample was dominated by Arcobacter (50%), followed by Acinetobacter (19%) and Firmicutes (18%).

Key words: oil reservoir, bacterial community structure, 16S rDNA clone library, amplified ribosomal DNA restriction analysis, Laizhou Bay, artificial reef, macrobenthos.