致密油藏化能自养微生物生长规律及其氧化活性研究

Growth law and oxidation activity of chemoautotrophicmicroorganisms in low-tight permeability reservoir

为了探明致密油藏化能自养微生物利用催化岩石耗氧功能辅助空气驱提高采收率的机理,针对注气开发致密油藏注氧安全问题,开展了对致密油藏化能自养氧化亚铁硫杆菌的富集筛选,并探究了氧化亚铁硫杆菌的生长规律以及其作用氧化矿物中亚铁、硫以及其生物活性等效能,结果表明:1)高生物量活性的氧化亚铁硫杆菌可生长代谢产生酸性环境(pH值小于2),从而加速了矿物中亚铁和硫的氧化还原;2)反应体系中亚铁氧化率达到91%,硫氧化率为57.8%;3)岩石矿物质亚铁和硫的氧化活性与微生物的生物活性成正相关关系;4)油藏化能自养微生物通过催化矿物中亚铁氧化耗氧,介导硫氧化还原产生SO_(4)^(2-),促使体系pH值下降,酸性环境利于矿物溶蚀分解,进而加速微生物催化岩石耗氧或矿化速率,达到耗氧增渗驱油目的。该研究成果,对化能自养微生物强化减氧空气复合驱技术现场应用提供指导意义。

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 SO_(4)^(2-),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.