Modelling the Coupled Effects of Temperature, Injection Rate and Microbial Kinetic Parameters on Oil Recovery by Microbial Flooding

Abstract

Abstract Before the implementation of microbial enhanced oil recovery (MEOR) technique in reservoirs, the microbes used in the MEOR process must be characterized based on the reservoir conditions that include reservoir temperature and also based on the microbe's kinetic parameters that includes yield of microbes with respect to nutrient (YXN) and yield of biosurfactants with respect to nutrients (YPN) for efficient recovery of crude oil from hydrocarbon reservoirs. In addition to chrecterization of microbes based on the reservoir temperature and on its kinetic parameters, the operational condition such as injection rate has also to be selected suitably for better oil recovery and to make the microbial enhanced oil recovery (MEOR) process an efficient technique. Hence in the present study, sensitivity analysis of reservoir temperature, injection rate and microbial kinetic parametrs on MEOR processes has been carried out to characterize the microbes and to identify the suitable injection rate for the MEOR process. For this purpose, a black oil microbial enhanced oil recovery (MEOR) simulator has been developed by coupling of thermo-hydro-biochemical multispecies reactive transport model with the non-isothermal multiphase fluid flow model that can predict the oil recovery at varied reservoir temperature conditions. The developed mathematical model has been solved numerically by finite volume discretization technique. The identification of suitable conditions of microbe, nutrient and injection rate to maximize the oil recovery has been carried out by investigating the sensitivity of reservoir temperature, injection flow rate and yield of microbes with respect to nutrient (YXN), yield of biosurfactants with respect to nutrients (YPN) on MEOR processes. It is found that the microbes used for MEOR application should have its survivable temperature range within the reservoir temperature for an effective MEOR application. Further, it is observed that for maximizing the oil recovery by microbial flooding process, the adopted injection rate should increases the capillary number to 10-3 within the reservoir which has to be achieved by increasing the mean aqueous phase fluid velocity and also by lowering the Interfacial tension. Finally, it is also found that more of the residual oil is recovered when the utilization of nutrients for biosurfacatnt production is greater or equal to the nutrients utilized for the microbial growth. Hence for an efficient MEOR application, the nutrient selected for the application should yield more biosurfactants than yielding the microbes that are selected for the MEOR application.