嗜烃乳化功能菌在多孔介质中的生长规律及驱油机理

Study on growth law and oil displacement mechanism of hydrocarbonophilic emulsifying bacteria in porous media

嗜热脂肪地芽孢杆菌Geobacillus stearothermophilus SL-1(简称SL-1)菌是从油藏环境中分离获得的一种嗜烃乳化功能菌,烃类乳化能力强,适宜生长温度为65~70℃。利用微观可视模型和岩心填砂模型,对该菌进行了多孔介质中的生长分布规律及驱油机理研究。结果表明,高温高压油藏环境下,与空白对照只添加激活剂体系激活内源菌相比,添加SL-1菌后可以改变孔壁润湿性,乳化膜状油,剥离盲端油,二次水驱后残余油驱替能力显著增强。物理模拟驱油实验显示,外源菌+内源菌体系提高原油采收率最高达13.5%,内源菌提高原油采收率为8.8%,外源菌发酵液提高原油采收率为7.2%;外源菌+内源菌体系中微生物数量最高,基因拷贝数约为109 copies/mL,内源菌体系中微生物数量约为107 copies/mL,外源菌发酵液体系中微生物数量最低,约为102 copies/mL。4轮次注入培养中Geobacillus菌始终是微生物生态系统的优势菌群之一,该菌数量与岩心残余油饱和度呈负相关。显示出嗜烃乳化菌在油藏环境下具有增加微生物数量,强化微生物驱油效果的重要作用。

The Geobacillus stearothermophilus SL-1(referred to as SL-1)is a hydrocarbonophilic emulsifying bacterium iso⁃lated from oil reservoir environment.It has strong emulsifying ability for hydrocarbons,with the suitable growth temperature at 65-70℃.The oil displacement mechanism and growth law of SL-1 bacteria in porous media were studied by a micro⁃scopic visual model and a core sand-packed model.Results demonstrate that in the high-temperature and high-pressure reservoir environment,the addition of SL-1 bacteria can change the wettability of the pore wall,emulsify film-like oil,and strip blind end oil,compared with single activator system for endogenous bacteria in the blank control group.Besides,resid⁃ual oil displacement is significantly enhanced after the secondary water flooding.Physical simulations of oil displacement show that the combination of exogenous and endogenous bacteria can enhance oil recovery by up to 13.5%,followed by 8.8%with the only endogenous bacteria and 7.2%with the only exogenous bacteria.The number of microorganisms in the combined system of exogenous and endogenous bacteria is the highest,with the gene copy number of about 109 copies/mL,followed by that in the system with only endogenous bacteria about 107 copies/mL,and then that in the system with only ex⁃ogenous bacteria about 102 copies/mL.Geobacillus has always been activated to be one of the dominant bacteria in the cul⁃ture solution during four rounds of injection,and its concentration in the produced fluid is negatively correlated with the re⁃sidual oil saturation of core.It reveals that the hydrocarbonophilic emulsifying bacteria have an important role in increasing the number of microorganisms and enhancing microbial oil displacement in the reservoir environment.