Impact of a Microbial-Enhanced Oil Recovery Field Trial on Microbial Communities in a Low-Temperature Heavy Oil Reservoir

摘要

In this experiment, air and nutrients were injected into a low temperature heavy oil reservoir to initiate an indigenous microbial enhanced oil recovery (MEOR) process with a cumulative increment of 1872 t heavy oil. This study reveals the response of microbial communities in the field before and during MEOR based on culture-dependent enrichment and culture-independent 16S rRNA gene clone library methods. The results showed that it was easy to activate the biosurfactant-producing bacteria Pseudomonas in laboratory conditions, and the bacteria were also the dominant present group in the mixed oil-water samples after MEOR. Fermentative and hydrocarbon-oxidizing bacteria increased by 300-500%, and the acetate ion concentration also significantly increased. Microbial activity of Pseudomonas and the metabolic products including biosurfactants were proposed to be the primary mechanisms for improving heavy oil recovery. The results of this experiment can serve as a useful resource for monitoring MEOR-related microbial population, and for future related experiments.