多孔介质中微生物生长与衰亡过程介观分析

MESOSCOPIC ANALYSIS ON MICROBIAL GROWTH AND DECAY PROCESS IN POROUS MEDIA

采用LBM-IBM耦合方法模拟多孔介质中流场,应用细胞自动机模型模拟多孔介质表面微生物生长衰亡过程,在介观层面上揭示生物堵塞的动态发展过程及其造成多孔介质渗透性能改变的本质。研究发现:当营养物入口浓度增加100%时,30 h内相对渗透率衰减增加6.25%~45.5%;且生物堵塞存在淤堵临界时刻,随着营养物入口浓度增加而提前。不同条件下,多孔介质渗透性能均呈不同程度的下降趋势,多孔介质内生物堵塞在空间分布上均呈明显的不均匀性。生物增长具有浓度趋向性,局部孔隙内微生物生长衰亡行为决定了多孔介质的堵塞程度,但部分生物的衰亡不会改变多孔介质整体渗透性能的下降趋势。温度升高25%,多孔介质相对渗透率衰减最高可增加5倍以上,且不同位置生物堵塞对温度的敏感度存在显著差异。

In this paper, the LBM-IBM coupling method was used to simulate the flow field in porous media, and the cellular automata model was used to simulate the growth and decay process of microorganisms on the surface of porous media, to reveal the dynamic development process of biological blockage and the essence of the permeability change caused by the blockage in porous media at the mesoscopic level. The study found that when the inlet concentration of nutrients increased by 100%, the relative permeability coefficient attenuation increased by 6.25%~45.5% within 30 hours. There was a critical moment of blockage in biological plugging, and the critical moment of blockage in porous media biofilm was advanced with the increase of nutrient inlet concentration. Under different conditions, the permeability of porous media showed a decreasing trend in different degrees, and the spatial distribution of biological blockage in porous media showed obvious heterogeneity. The growth of organisms was concentration-oriented, and the growth and decay behavior of microorganisms in local pores determined the plugging degree of porous media, but the decline of some organisms didn’t change the declining trend of the overall permeability of porous media. When the temperature rose by 25%, the relative permeability coefficient of porous media attenuation could increase by more than 5 times. The sensitivity of biological plugs to temperature was different in different locations.