The Study On Application Of Microbial Molecular Ecology In The Microbial Enhanced Oil Recovery

Microbial enhanced oil recovery technology is a new rising high-tech which can enhanced crude oil recovery rate. The main approaches is that through the microbial metabolism the underground crude oil can be degradated, the viscosity of the crude oil can be reduced, and the mobility and formation pressure of the crude oil can be increased, so the crude oil recovery rate can be enhanced. At present there still are many defects in the choice of strains for different reservoirs, the micro-flooding enhanced oil recovery mechanism, the growth of micro-organisms in porous media, and the reproduction and migration, as well as the effectiveness of MEOR. Especially the track of the microbial agent in microbial enhanced oil recovery before and after is still not so clear, and a lot of oil displacement mechanism and the effectiveness could not be verified and explained yet. In recent years, with the rapid development of microbial molecular ecology, microbial community structure and function of resolution, as well as communities change research can be achieved.Through the research for the reservoir system, the molecular ecology monitoring methods based on the microbial enhanced oil recovery process, we separated the profile control bacteria, fungi, made the phylogenetic analysis, and constructed the gene library for the low-permeability reservoirs, the before and after of the microbial enhanced oil recovery polymer flooding process,at the same time carried out the study of population dynamics on the single wells.We isolated 4 strains of bacteria profile modification TP-1, TP-2 from the reservoir. The similar values of 16S rDNA sequence between and the Strain TP-1 Enterobacter cloacae (EU884395) reach to 99%, TP-2 Bacillus licheniformis (AY0539620) reach to 99.0%, so the TP-2 DM-1 is identified as Bacillus licheniformis. Profile control bacteria plugging experiments showed that when injected into the para Seda 500mg / L ? PV, the permeability reduction rate can reach 80%. Artificial core experiment showed that when the injected amount of optimization for the 250mg / L ? PV, the recovery average of 3.9%.We isolated three bacteria, the best culture conditions for both aerobic training; the best carbon source is a liquid paraffin whose the best concentration is 1%; the best nitrogen source is yeast extract whose the best concentration is 1g / l ; the best culture temperature on the ground is 40℃, underground temperature is 45℃; the optimum salinity is 0.5%.We constructed the 16Sr DNA gene library for the typical low-permeability No.8 oil plant and No.10 oil plant, while we did the PCR-DGGE population analysis for the different wells. The research shows that bacteria are mainly distributed in theγ-Proteobacteria (Gammaproteobacteria) ( 67%), in which theγ-Proteobacteria is for 49% in the total library, Pseudomonas is 17%. The PCR-DGGE analysis of different well showed that the population diversity is resch, and the dominant species is Paracoccus sp., Brevundimonas sp, Pseudomonas sp , Acinetobacter sp., at the same time there are a lot of unknown bacteria.The bacteria in No.10 oil plant mainly includeγ-Proteobacteria (Gammaproteobacteria) (64%), the rest are theα-Proteobacteria (Alphaproteobacteria) for 6%, Sphingobacteria for 8%, theγ-Proteobacteria Acinetobacter for 43% of the total, Pseudomonas for 21%. The PCR-DGGE analysis of different wellhead showed that the population diversity is resch, the difference is obviously, the bands are mainly distributed in Desulfovibrio desulfuricans., Thauera sp. Eubacterium sp., Hydrogenophaga taeniospiralis, Actinobacteria bacterium, Thermotoga sp., also there are many unknown sequences.Polymer flooding Flooding microbial testing laboratory study results show that the flooding could further enhance the microbial oil recovery rate 4.0 percentage points; field test, including filtering out microbial polymer flooding, flooding bacteria, testing enhanced oil recovery up to 5 percentage points; the formation of a set of microbial control and flooding into the process supporting technology.There are different effects of microbial enhanced oil recovery in different wells. The population dynamics succession analysis of North-2-4-P49 single well showed that the dominant band is clearly and the individual stocks have increased trend. On the whole, the microbial populations are rich. The main dominant species are Pseudomonas sp., Acinetobacter sp., Clostridia bacterium, Thermomicrobium sp., Agrobacterium sp., Firmicutes bacterium, while there still are the unknown bacteria. The dominant species of North-2-J4-P47 are Acinetobacter johnsonii, Pseudomonas fluorescens., Pseudomonas sp., Bosea sp., Syntrophothermus lipocalidus, Aeromonas media, while the unknown bands still existed the unknown bacteria.At the same time we constructed the 16SrDNA gene library during the different stage of the post-microbial enhanced oil recovery polymer flooding process. The polymer flooding before the population is mainly uncultured bacterium, which accounted for 88.6%of the total number, the known bacteria concludeε- Proteobacteria (Epsilonproteobacteria) 5.7%, the rest of theγ-Proteobacteria (Gammaproteobacteria) accounted for 4.7%, Firmicutes (Firmicutes) accounted for 1%. During the microbial enhanced oil recovery process, the uncultured bacterium accounted for 55% of the total number, and the known bacteria include theγ-Proteobacteria (Gammaproteobacteria) 35% of the total number and the remainingδ-deformation of mycetes (Betaproteobacteria) 4%,α-Proteobacteria (Alphaproteobacteria) 3%,ε-Proteobacteria (Epsilonproteobacteria) 1%. The uncultured bacterium accounted for 84% of the total number, and the known bacteria include theγ-Proteobacteria (Gammaproteobacteria) accounted for 7% of the total number and the remainingα-Proteobacteria (Alphaproteobacteria) accounted for 3%,δ-Proteobacteria (Betaproteobacteria) accounted for 1%, Firmicutes (Firmicutes) 1%. The PCR-DGGE showd that at different time the diversity of population is rich, the dominant bands are obvious, and change significantly. The main dominant species are Pseudomonas sp., Acinetobacter sp., Clostridia bacterium, Thermomicrobium sp., Mesorhizobium plurifarium and a lot of unknown bacteria.The microbial molecular ecology play the great role in the monitoring of microbial enhanced oil recovery communities, the mechanisms of the microbial enhanced oil recovery and the efficiency of improving the oil recovery.