After the primary extraction in oil reservoirs up to 60 % of the oil remains trapped in the reservoir (Sen, 2008) Therefore, different mechanisms have been developed to get the oil out to the reservoir. One of these techniques is Microbial Enhanced Oil Recovery (MEOR) which is a technique used to produce more oil in a secondary extraction by using microbes in the reservoir. The main effects caused by microbes in oil recovery is the reduction of the interfacial tension between oil and water, wettability change of the rock and bioclogging caused by the growth and development of biofilm Among these mechanisms, interfacial tension reduction and biclogging is thought to have the greatest impact on recovery (Sen. 2008) In this work, we describe the growth of biofilm, the growth of the microbial population and the transport of nutrients using a pore network model We follow the previous models of Thullner et al. (Thullner, 2008) and Ezeuko et al (Ezeuko, 2011) in which the biofilm is considered as a permeable layer. We consider the biofilm and the bacteria separately Additionally, we assume that once a tube is full with biofilm. this biofilm can spread to the neighboring tubes Finally, we study the changes in the hydrody namic properties of the medium caused by the plugging of the pores and we study the flow diversion of water caused by plugging of the high permeability zones.
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