A mathematical model for microbial enhanced oil recovery using biopolymer-producing microorganism

Based on the analysis of bacterial behavior in different environments, a one-dimensional two-phase, five-component mathematical model was developed to simulate the biopolymer flooding process in porous media. The components of this mathematical model consist of oil, water, microorganisms, nutrients and metabolites, wherein the main metabolite is biopolymer. The equations of this numerical model take into account the decay and growth of microorganisms, nutrient consumption, biopolymer production, chemotaxis, convection-dispersion, water viscosity increment, adsorption, desorption. This newly presented model is validated with a classical simulator and a core flooding experiment. Variable microbial death rate in the presence or absence of nutrients is also considered as a factor, and a model of two death rates is used to modify the reaction kinetics equation accordingly. In this study, the sensitivity of the water viscosity and the death rate were analyzed through a simulator developed according to our mathematical model. We found that: (1) this simulator can simulate the microbial flooding process in reservoirs under different water viscosity functions; (2) microbial flooding has a positive effect on reducing water cut and increasing oil recovery of the reservoir when compared with water flooding; (3) the model of two death rates is better than that of single death rate for simulating the curve of water cut; (4) the higher the microbial death rate in the absence of nutrients, the more realistic the production of the metabolites.