一株采油功能菌株的筛选和评价

A Study on Screening and Evaluating the Strain Z25 For Microbial Enhanced Oil Recovery

从大庆油田采出液中分离得到一株采油功能菌Z25,经16S rDNA序列分析鉴定为Rhodococcus ruber。该菌株能利用烃类为唯一碳源生长并代谢生成生物表面活性剂,达到稳定期发酵液的乳化系数EI24为64%,最佳发酵时间为48小时。原油降解实验表明,该菌株能够降低油品的胶质沥青质含量和原油凝固点,使大庆油田3个稠油样的胶质沥青质含量分别从38.76%,33.25%,35.38%降至36.55%,30.31%,33.73%,凝固点分别从13.5℃,-5℃,3.3℃下降至8℃,-12℃,1℃,改善了原油的物性。同时,Rhodococcus ruberZ25菌株发酵液能够乳化原油,形成稳定的水包油型乳液,降低原油黏度,提高原油流动性;微生物发酵液还能够改善介质表面润湿性,将亲油表面转化为亲水表面。通过物理模拟驱油实验发现,该菌株能大幅提高低温稠油油藏的原油采收率,对三个油藏的采收率提高幅度分别为14.52%、11.71%和17.29%。

A hydrocarbon-oxidizing strain was isolated from the production water of Daqing Oilfield,which was identified as Rhodococcus ruber by 16S rDNA sequence analysis.The strain Z25 could grow using hydrocarbon as the only carbon source and produced biosurfactant.The emulsification index（EI24） of the microbial culture broth（MCB） achieved 64% at stationary phase.The crude oil biodegradation experiments indicated that the contents of gum and asphaltine of three oil samples from Daqing oil field were decreased from 38.76%,33.25% and 35.38%,respectively,to 36.55%,30.31% and 33.73%,respectively,while the freezing points were declined from 13.5℃,-5℃ and 3.3℃,respectively,to 8℃,-12℃ and 1℃,respectively.The MCB could form the oil-in-water emulsion and reduce the viscosity of the oil phase,which could improve greatly the fluidity of the crude oil.Meanwhile,the wettability of the surface of solid medium could be modified by the MCB.The EOR ability of the strain Z25 was evaluated by the physical simulation experiment and the oil recoveries were enhanced by 14.52%,11.71% and 17.29% according to three different reservoir conditions.