Mechanism of Microbe Propagation in Heterogeneous Porous Media and Analysis of Various MEOR Processes Involved in Microbe Transportation

摘要

A potentially inexpensive method, Microbial Enhanced Oil Recovery (MEOR), may prove valuable and economical. Most conventional oil recovery processes are only able to recover from 15 to 50% of the available oil in the reservoir. The exploitation of this technology can extend the average well life without increasing excessive lifting costs. Before lucratively implementing the MEOR process in heterogeneous porous media, the problems related to transport of that particular microbe need to be addressed. Potential microbe strains must be transported deep into the heterogeneous reservoir through active metabolites generated in-situ in order to contact trapped oil. This paper accentuates a bench-scale laboratory investigation of microbe transportation, not only in sandstone cores but also in sand packed columns and its relationship with improved oil sweep efficiency. This paper presents various oil recovery processes through a biosurfactant producer (Bacillus Subtilis). These processes include continuous microbe flooding, inoculation of microbes followed by nutrient injection and microbe inoculation followed by repeated cycles of static incubation. An improved oil sweep efficiency of 25-35% has been observed through these processes. A microbe migration of 1 - 2 ft/day has also been revealed. The most feasible process among these three processes for transport of microbe in heterogeneous porous media has been evaluated and presented through injection of nutrients followed by static incubation which includes multiplication and migration of microbe cells. The results of multistage microbe propagation in laboratory simulation experiments have also been presented. Analysis of these processes suggests the criterion of selecting microbe cells with favorable transport properties in porous media.