Studies On Transport Process Of Oil Reservoir Microorganism In Porous Medium

MEOR(Microbial enhanced oil recovery)technology was a cost-effective, no formation damage, facilitate to inject, environmentally friendly tertiary method, and have a great potential in field application. Effective transport and growth of bacteria cells in porous medium has been a key to MEOR technological success, whether used microorganism was exogenous or indigenous. In recent years considerable efforts have been put into the effect of microbial metabolic products on physical and chemical properties of oil and water, little information existed concerning the growth, transport and metabolism of bacteria cells in oil reservoir environments. Some of phenomena were still not well understand.In this studies, displacement experiments of distinct core models including natural sand cores and sandpacks constructed out of unconsolidated silica sand particles were conducted to examine transport and growth process of oil reservoir microorganism in porous medium under simulated oil reservoir conditions (high temperature, high pressure and no oxygen) and to determine core permeability and hydrodynamic condition that bacteria cells could transport through porous medium. The effects of microorganism growth and multiplication on the oil recovery efficiency from water-flooded sandpacks were investigated under a transportable core condition. The main results and conclusions were summarized as follows:1 A ferment bacteria was isolated under laboratory simulated oil reservoir condition (high temperature and no oxygen). The strain was identified by sequencing of the 16S rRNA gene. Effects of temperature, salinity and pH on growth were examined and the optimum growth conditions were determined. Microbial metabolic products were analyzed.Results from the MPN counts analysis of microbial communities in formation water of the block Zhan-3 showed that main microbial populations residing in oil reservoir included total growth bacteria, hydrocarbon-oxidizing bacteria, ferment bacteria, sulfate-reducing bacteria, nitrate-reducing bacteria and methane-producing bacteria. The strain A3 was isolated from produced water in the block Zhan-3 by Hungate anaerobic operation technique. God-shaped cell of 0.6-1.0μm in diameter and 3.5-4.0μm in length, gram-negative. The temperature range for growth was 45-75℃, optimum growth occurred 50-65℃; the salinity range was 5-80g/L NaCl with an optimum at 10-70g/L NaCl; the optimum pH for growth was 6.8, however, growth occurred between pH 4.5-9.8. A3 was strictly anaerobic, and could utilize glucose to produce acetate and bio-surfactants, reduce nitrate to N2. On the basis of 16S rRNA gene sequence analysis of the strain A3, it was most closely related to Halomonas boliviensis (AY245449) with a...