Screening And Flooding Evaluation Of The Thermophilic Hydrocarbon-degrading Bacteria

Microbial enhanced oil recovery refers to microbial itself and its metabolites interacting with crude oil to get physical and chemical changes.These changes can reduce the viscosity of crude oil and improve the liquidity to improve EOR.In recent years,the drilling technology has developed a lot,the depth of the wells gradually increase,the temperature of underground reservoir increased as well,most of the wells has been above 50°C,Conventional microbial products are no longer suitable for high temperature wells,so if we want to change the traditional disadvantages of micro-organisms,we must separate out better bacteria living with crude oil under high temperature conditions for the field applications.In this paper,we separate and select a kind of germs withstanding high temperatures from the produced fluid samples of three blocks of Shengli Oilfield with the method of expanding oil ring and the bacilli surface tension,we named this bacteria CK2,we have a study on bacterial morphology observation,bio-chemical properties and identification of molecular biology,evaluate the adaptability of this bacteria in reservoirs considering four main factors like temperature,pH,salinity,oxygen dissolvation to choose the best conditions for bacteria,The bacteria were co-cultured with crude oil,we analyze the changes in the nature of oil and bacilli(emulsificate,the IR of crude oil,Crude oil components,viscosity,emulsification index),finally we use sand filling tubes of three different penetration levels(0.3D,0.7D,1.1D)to evaluate the EOR flooding effects and provide theory fundation and support of technique in the field application.The research suggest CK2 belongs Bacillus,we separate and purificate the metabolites which were identified Glycolipid bio-surfactant by IR,The absorbance of the bacteria shows that CK2 can live in temperatures between 35~75°C and 55°C is the best choice,CK2 can live in PH 5~9,and 7 is the best PH,CK2 can live in the salinity percentage from 0.5%~5%,When the salinity is 10%,the bacteria grow in poor condition,the best salinity is 0.5%,the best shaker speed is 160r/min,The bacteria were co-cultured with crude oil,the emulsification is obvious,the changes of IR show that the aldehydes and ketones increase the crude oil's heavy part decreased,and the light components increased,three oil samples' viscosity reduced 30.1%,23.9%,19.6%,the emulsification index of diesel fuel reaches up to 99%,we can see from the flooding result that the raise proportion were7.5%,10.6%,6.1%,the study can prove CK2 has the value of large-scale production and field applications.