Study On The Interaction Between Microorganisms And Rock Minerals Under Simulated Reservoir Conditions

In the oil reservoir,there is a ternary reaction system composed of fluid(gas,water and oil),reservoir microorganisms and minerals in reservoir rocks,with multiple sets of interaction relationships.However,microbial enhanced oil recovery(MEOR)technology has long focused only on the interaction between microorganisms and crude oil and its MEOR mechanisms,while the interaction between microorganisms and reservoir minerals and its MEOR potential have not been given much attention.In this paper,in-situ microorganisms and minerals in Changqing B153 ultra-low permeability reservoir were studied.Bacillus sp.was selected to conduct interaction experiment with dolomite,calcite and mica.Pseudomonas stutzeri and illite were selected to conduct microbial degradation of crude oil experiment under the influence of clay mineral.Select Bacillus mucilaginosus,Bacillus cereus,Pseudomonas aeruginosa and Acinetobacter lwoffii to conduct MEOR simulation experiment on artificial and natural cores,respectively.Based on the understanding of the reservoir and the above research results,field tests successfully carried out in B153 reservoir.The results show that the solubilities of dolomite,calcite and mica can be increased to varying degrees by Bacillus sp..At the same time,minerals can promote the growth of Bacillus sp..Increased dissolution is caused by microorganisms,cation effect and partial pressure of metabolic gas CO2.The particle size of minerals affects the solubilization effect.Clay mineral illite reduces the total degradation rate of crude oil by Pseudomonas stutzeri.Illite inhibits the degradation of all 64 saturated hydrocarbons and 50 aromatic hydrocarbons(50/96),while promoting the degradation of 45 aromatic hydrocarbons(45/96).The number of benzene rings in aromatic hydrocarbons,the number and chain length of substituents,and whether there are heteroatoms affect the role of illite.At the same time,it was observed that the crystal diffraction characteristics of illite changed to kaolinite during the crude oil biodegradation.In the MEOR laboratory experiment simulating B153 reservoir conditions,four microorganisms can improve the oil recovery of artificial and natural cores.The order of MEOR capacity from high to low is Pseudomonas aeruginosa,Bacillus cereus,Acinetobacter lwoffii and Bacillus mucilaginosus.All four microorganisms have the ability to increase mineral dissolution,and their solubilization effect on natural cores is stronger than that on artificial cores.The MEOR field test of B153 oil reservoir further proves that the interaction between microorganisms and rock minerals promotes microbial growth,increases the organic matter content in water,and improves water-oil mobility ratio.These lead to a decrease in injection-production ratio,an increase in formation pressure,an increase in water absorption profile,a decrease in natural decline rate and water content,resulting in a 2%increase in production.