Estimation of metabolic activity of Enterobacter cloacae TU-7A for MEOR field tests

Enterobacter cloacae TU-7A strain is a CO2 producing bacterium and is being used as one of the injecting bacteria in Jilin Oil Field, China. For monitoring the metabolic activity of TU-7 A, possibility of utilization of 2, 3-butanediol, which is one of the metabolites, is discussed. Results are summarized as follows. 1) TU-7A has two (main) metabolic pathways for producing CO2, that is butanediol fermentation and enzymatical decomposition of formic acid which is one of the metabolites. The amount of CO2 calculated on the base of these pathways agreed fairly well with that measured by gas analysis. 2) Influence of the concentration of molasses as substrate and the addition of phosphate into the medium on the production of CO2 may be taken into account. 3) In the formation water of target block of the oil field and the molasses medium, there is no bacterium which produces 2, 3-butanediol. 4) Absorption test of 2, 3-butanediol on silica sand grains clarified no consumption, so that the quantity of butanediol may be measurable by analyzing the produced water. 5) All results may confirm the possibility of utilization of 2, 3-butanediol for monitoring the amount of CO2 produced.