油藏本源反硝化功能菌的产气作用（N2O）及对原油物性的影响

Effect of N2O produced by indigenous denitrifiers in oil reservoir on the physical properties of crude oil

利用叠皿夹层培养法从新疆油田采出水中筛选到8株反硝化菌株T1、D1、D44、D46、D15、S1、S2、S6,经16S r DNA序列测定鉴定分析,这8株菌分别与施氏假单胞菌(T1、D1、D44)、恶臭假单胞菌(D46、D15)和铜绿假单胞菌(S1、S2、S6)相似,相似度均达到100%。通过室内批次培养试验,评价了这8株菌利用不同碳源的反硝化产气作用(N2O)及对原油物性的影响。结果表明:在以蔗糖为碳源时,产气量最大,以甘油为碳源时,产N2O气浓度最高;菌株反硝化代谢过程导致原油体积膨胀和粘度降低,膨胀率与N2O气体浓度呈显著正相关,相关系数为0.983,但与产气体积无相关性;铜绿假单胞菌株S1、S2、S6在以甘油为唯一碳源时产生少量表面活性剂(530~730 mg·L^-1),可降低表面张力并具有乳化原油的作用,但其产气量较少,对原油的膨胀与降粘作用低于其他反硝化菌株。研究提示,在筛选采油功能菌时,菌株反硝化产N2O气体的能力应给予足够重视。

The success of microbial enhanced oil recovery(MEOR)relies on complex microbial processes.Nevertheless,the contribution and mechanism of in-situ denitrification to microbial oil recovery remain unclear.In this study,eight denitrifying bacterial strains,designated T1,D1,D44,D46,D15,S1,S2 and S6,were isolated from the produced water of Xinjiang Oilfield,China,by a double layered plate method.The16 S r DNA gene sequences of these denitrifying strains shared 100%similarity with Pseudomonas stutzeri(T1,D1,and D44),Pseudomonas putida(D46 and D15),and Pseudomonas aeruginosa(S1,S2,S6),respectively.The N2O production effects of these strains on the physical properties of crude oil were evaluated with batch experiment.Results showed that the highest total gas yield was observed with sucrose as carbon source,and the maximal concentration of N2O occurred with glycerol as carbon source.The denitrification process by these bacterial strains led to volume expansion and viscosity reduction of crude oil.Crude oil expansion rate was positively correlated with the concentration of N2O,with a correlation coefficient of 0.983,but not correlated with the volume of total gas production.Strain S1,S2,and S6 produced 530-730 mg·L^-1 of surfactant using glycerol as ole carbon source,which could reduce surface tension and emulsify crude oil.However,these surfactant-producing strains produced less N2O,exhibited weaker effects on oil swelling and viscosity reduction,compared to the none-surfactant-producing denitrifying strains.Our results suggested that more attention should be paid to the ability of N2O production by denitrifying bacteria when exploiting microbial resources towards enhancing oil recovery.