Research On Formation Mechanism And Influence Factors Of Emulsion On Microbial Enhanced Oil Recovery

Emulsification phenomenon is very common in the tertiary oil recovery, Oil-in-water emulsion reduce the viscosity of crude oil and water in oil emulsion can improve the sweep area of oil so as to improve oil recovery. But great majority studies of emulsion aim at chemical displacement of reservoir oil. Experiments found that pseudomonas aeruginosa role of Xinjiang crude oil to form a stable emulsion. So study of emulsion is a significant and novelty issue.In this thesis, based on the dynamic changes of the biological emulsion characteristics and spatial distribution characteristics of system analysis, mainly aimed at the biological stability emulsion formation mechanism and influencing factors were studied.1. Pseudomonas aeruginosa WJ-1 using crude oil as carbon source to produce biosurfactant rhamnolipid, rhamnose molecules on the oil-water interface in directional adsorption can reduce the oil-water interface on unit area, to prevent droplet spontaneously gather and lead to dynamic instability of the system is prone to spontaneous emulsification. At the same time, the emulsion droplet radius increased the oil-water boundary area, thus increasing the bacteria and oil contact. Rhamnose oil-wet structure of water molecules, make rhamnose molecular directional adsorption on the surface of oil droplets can form micelle, stable surface active agent through the periphery of the hydrophilic group, solubilization of crude oil in the water phase, not only improves the availability of crude oil, but also increase the stability of the emulsion.2. Bacteria because of its hydrophilic lipophilic adsorption on the oil-water interface, the interaction between cells form a stable network structure, enhanced the oil interface membrane mechanical strength, preventing droplet rupture; and space obstacle barrier formed between adjacent droplets, obstruct oil droplets coalescence, increase the stability of the emulsion.3. After a series of comparison, the results proved that the emulsion is more stable between 0.3% and 0.5%. under the action of different content of moisture and rhamnolipid, when rhamnolipid concentrations above the critical micelle concentration (0.02g/L), degree of emulsification of crude oil increase with concentration of rhamnolipid and moisture. Microbial-mediated emulsification of crude oil is the result of interaction between microbial biomass and metabolites, only if the water content is 90%, emulsified state the best. In a determined rhamnolipid concentration, microbe mediated emulsion is also consistent with the theory of phase volume:when the moisture content less than 20%, there is a trend of O/W into W/O emulsion.