Growth law and oxidation activity of chemoautotrophic microorganisms in low-tight permeability reservoir
In order to explor the mechanism of enhancing oil recovery by using oxygen consumption function of catalytic rock to assist air flooding in tight oil reservoirs,the enrichment and screening of thiobacillus ferrooxidans in tight oil reservoirs were carried out in view of the safety of oxygen injection in tight oil reservoirs.The growth rule of thiobacillus ferrooxidans and its effects on the oxidation of ferrous and sulfur in minerals were investigated.The results showed that:1)Thiobacillus ferrooxidans with high biomass activity can grow and metabolize to produce acidic environment(pH<2),thus accelerating the redox of ferrous and sulfur in minerals;2)The oxidation rate of ferrous and sulfur reached 91%and 57.8%in the reaction system;3)The oxidation activities of ferrous and sulfur are positively correlated with the biological activities of microorganisms;4)Reservoir autotrophic microorganisms catalyze the oxygen consumption of ferrous oxidation in minerals,mediating sulfur redox to produce SO42-,which reduces the pH of the system,and the acidic environment is conducive to the dissolution and decomposition of minerals,thus accelerating the oxygen consumption or mineralization rate of the rocks catalyzed by microorganisms to achieve the purpose of oxygen consumption,permeability and oil displacement.The above results will not only further expand the knowledge of geochemical reactions catalyzed by reservoir chemoautotrophs for rock oxygen consumption,but also provide guidance for the field application of chemoautotrophs for enhanced oxygen-reducing air composite flooding technology.