Impact of an indigenous microbial enhanced oil recovery field trial on microbial community structure in a high pour-point oil reservoir

Abstract

Based on preliminary investigation of microbial populations in a high pour-point oil reservoir, an indigenous microbial enhanced oil recovery (MEOR) field trial was carried out. The purpose of the study is to reveal the impact of the indigenous MEOR process on microbial community structure in the oil reservoir using 16Sr DNA clone library technique. The detailed monitoring results showed significant response of microbial communities during the field trial and large discrepancies of stimulated microorganisms in the laboratory and in the natural oil reservoir. More specifically, after nutrients injection, the original dominant populations of Petrobacter and Alishewanella in the production wells almost disappeared. The expected desirable population of Pseudomonas aeruginosa, determined by enrichment experiments in laboratory, was stimulated successfully in two wells of the five monitored wells. Unexpectedly, another potential population of Pseudomonas pseudoalcaligenes which were not detected in the enrichment culture in laboratory was stimulated in the other three monitored production wells. In this study, monitoring of microbial community displayed a comprehensive alteration of microbial populations during the field trial to remedy the deficiency of culture-dependent monitoring methods. The results would help to develop and apply more MEOR processes.

Microbial diversity in long-term water-flooded oil reservoirs with different in situ temperatures in China

“…phylum Gammaproteobacteria were often detected in oil reservoirs7826. We detected these bacteria in all reservoirs, except for the lower temperature of No.…”

“…In the water samples of the mesothermic oil reservoir Kong 2 and the higher temperature oil reservoir V4, bacteria belonging to CFB group, accounted to 2.7% and 3.1%, respectively. Similarity, most of them were uncultured but related to environmental sequences associated with oil reservoirs262829. Although members of CFB group were detected widely in samples collected from oil reservoirs, their ecological significance and indigenous nature are not clear due to their uncultured characteristics, which underlined the need to isolate and characterize pure cultures of these microorganisms.…”

“…The 25μl PCR reacting system contains a 2.5μl of 10×PCR buffer (Mg 2+ plus), 10 nmol of deoxynucleotide triphosphates, 1 U Taq DNA polymerase (TakaRa), 10 pmol of each primer, and 1μl of template DNA. The thermal cycling conditions were as follows: an initial denaturation at 94°C for 5 min, 40 cycles of 94°C for 30 sec, 56°C for 60 sec, 72°C for 90 sec, and a final extension step of 72°C for 10 min2636. Amplified fragments were approximately 1450 bp.…”

“…During the re-amplification procedure, a small quantity of cells of putative clones was used as template DNA in the reaction mixtures. PCR products of positive clones were classified into different operational taxonomic units (OTUs) using amplified ribosomal DNA restriction analysis (ARDRA) with Hinf I and Hae III (TaKaRa)2636. Representative clones were selected for sequencing which was performed using an ABI PRISM 3730 DNA sequencer (SinoGenoMax Co., Ltd., Beijing, China).…”

Laboratory studies of rice bran as a carbon source to stimulate indigenous microorganisms in oil reservoirs

“…Indigenous microorganisms, which naturally inhabit oil reservoirs, show a greater metabolic activity than exogenous ones due to their long-term adaptation (CastorenCortés et al 2012;Lazar et al 2007). Therefore, indigenous microorganisms activated MEOR (IMEOR) has greater efficiency than using exogenous ones (Yao et al 2012;Zhang et al 2012). Stimulation, growth and propagation of beneficial microorganisms that can contribute to producing effective metabolites are critical to the application of IMEOR (Zhang et al 2010).…”