Research On The Metabolic Mechanism Of Gas-producing Microorganisms In Oil Reservoirs

Base on literatures researches about applications of MEOR nowadays and consideration of the oxygenic character of reservoir, the paper applied two kinds of reservoirs to screen nutrient systems for gas-producing microorganisms, and studied biogas production ability and metabolic mechanisms in porous medium in order to understand the mechanism of MEOR further.The paper firstly showed that nutrient systems selected could stimulate biogases production by gas-producing microorganisms; the composition of biogases included N2, H2 and CO2, the predominant composition depended on the nutrient systems; the pressure of the reservoir increased with the biogases production, based on the composition and content of biogas, and did not only matter with the volume of gases; the pressure would not restrict biogas production; nutrients addition effectively stimulated microorganisms to produce organic acids which were not proportional to the biogases produced; the predominant microorganisms changed after activation, and the gas-producing microorganism in Yue er 2-7 was identified as Halomonas sp.Secondly, the paper established the methods and systems for biogas investigation in anaerobic environment. The biological, physi-chemical processes in porous medium were studied; the conversion of nutrients, the changes of gas-producing microorganisms especially Methane Producing Bacteria, the gas production capability and their contribution to recovery were all explored at the same time. The results showed that Fermentative Bacteria kept at a higher concentration (105-108 cells/ml) in anaerobic metabolism; oxidation-reduction redox and the active of Methane Producing Bacteria influenced Sulfate Reducing Bacteria; acetate stimulated gas production effectively, the concentration of Methane Producing Bacteria came up to 107 cells/ml; the major composition of biogas was CH4; CH4was detected in blank control which proved the Two-Step activation theory, the limited concentration for CH4 production was 180.0 mg/L-614.8 mg/L; the predominant organic acid included acetate, lactate, propionic acid etc; the concentration of carbonate decreased and approached zero after one month cultivation; the pressure in reservoir increased, the ratio of water to oil decreased, and recovery increased obviously.Finally, the results of micro-model showed that large quantities of biogases produced, oil viscosity decreased, and fluidity increased. The biogas produced had a wide range of elasticity, overcame the capillary and induced residual oil getting together.