Research On Technology Of Increasing Recovery Efficiency Of Heavy Oil Emulsified Functional Bacteria

Microbial oil recovery technology is rising with the development of tertiary oil recovery.Microbial strains grow and metabolize in the formation,improve the formation environment and reservoir physical properties,interact with heavy oil to produce an emulsifying and viscosity reducing effect,increase mobility,and improve the recovery rate of heavy oil.The purpose of this study is to screen the oil recovery functional bacteria that can effectively reduce the viscosity of heavy oil,study their environmental adaptability,optimize the culture conditions,investigate their metabolic characteristics of crude oil,and to carry out field experiments of microbial huff and puff to investigate their enhanced oil recovery.In this study,the physical properties of a heavy oil with a viscosity of 10000 m Pa·s at 50 ? in Erdong block of Karamay Oilfield,Xinjiang,were determined.Based on this,an strain of oil recovery functional bacteria named LD was isolated from it.The result of molecular biological identification of LD was Pseudomonas aeruginosa.Accroding to the evaluation of its environmental adaptability,it was determined that the optimal growth p H value is 7,the optimal temperature is 40 ?,and it can withstand the mineralization degree of 12000 mg/L.The emulsification effect was examined by a shake flask experiment.The viscosity of the heavy oil can be reduced by more than 90%,the surface tension of the emulsion can be reduced to 30 m N/m,and the bacterial concentration can reach more than 1.3 Abs in 48 hours.With rhamnolipid content and bacterial concentration as indicators,the optimal carbon source of the culture medium was sunflower kernel oil and nitrogen source was sodium nitrate.With rhamnolipid content and bacterial concentration as indicators,the optimal carbon source of the culture medium was sunflower kernel oil and nitrogen source was sodium nitrate.After48 hours of culture,the yield of rhamnolipid of LD bacteria was 0.47 g/L,and the concentration of bacteria reached 2.81 Abs.This study examined the crude oil metabolism characteristics of LD bacteria based on oil samples from ten production oil wells in Erdong District of Karamay.Based on the analysis of four components and GC-MS of oil samples from 374 and J-11 wells with the most obvious emulsification effect,it is determined that LD bacteria can degrade a part of n-alkanes between n C22 and n C35 in the process of emulsification and viscosity reduction,decompose them into alkanes with smaller molecular weight,and then make use of them,so as to increase the relative abundance of n-alkanes between n C16 and n C22 in the gas chromatogram.The field test results based on LD bacteria showed that the stimulation effect of T20416,T20557 and T20426 wells is good,and the stimulation effect is stable and can last for at least 3 months.It has a certain oil-increasing effect on Well 22-2,but it was relatively low,while the oil production of T17-3 and T20578 wells has only maintained at a lower level.