Microbial Metabolism Of Reservoir Properties

The Microbial Enhanced Oil Recovery technology is a kind of method that utilizes the effect of microbe growth and metabolize in reservoir to meliorate the physical properties of rock as well as the fluids in reservoir and then enhances the oil recovery. The reservoir is a multi-phase system consisting of solid rock and liquid fluids. The properties of fluids and rocks in reservoir are vital factor influence on the MEOR. So the research to study the effect of the microbial metabolize on the surface of reservoir rock and the fluidity is very necessary.Based on experimental, the effect of the metabolism and metabolites of thermophilie-facultative bacteria utilizing hydrocarbons as sole carbon-source on crude oil, formation water and the wettability of rock surface have been studied through measurement of contact angles between rock surface and fluids and testament of the effect of microbe on the crude oil and formation water. The experiments carry out from the three aspects as follows: microbial ferment solution, bacterium and the upper liquid of microbial ferment solution. The results reveal the biochemistry mechanism of microbial enhance oil recovery initially, which will play a vital role in microbial enhanced oil recovery.This thesis is divided into four parts. The first part is an introduction of the MEOR and the wettability influence factors of the reservoir rock surface. The second part is regarding the effect of microbial metabolities on contact angles of rock surface; The third part deals with the effects of microbial metabolites on properties of oil and water. The last part presents conclusions.The main conclusions of this thesis are as follows:1. The experiments show that microbial ferment solution, the upper liquid of microbial ferment solution and the bacteria can alter the wettability of rock surface, reduce the contact angles between rock and water, change the wettability of sandstone from hydrophobicity to hydrophilicity, alter the capillary force of water flooding, minish the adhesive force of oil phase attaching to rock surface in different degrees. Among them the upper liquid of microbial ferment solution is the major part to influence the wettability of rock surface, and at the same time, the extent of influence has a close connection with the type of bacteria and the concentration of bacterial liquids.2. The experimental results, which are about the effects of microbial ferment solution, the upper liquid of microbial ferment solution and bacteria on the crude oil, indicate that the microbial ferment solution and the upper liquid of microbial ferment solution can decrease the viscosity of crude oil. After treating with microbes, the concentration of hydrocarbon components in crude oil is relatively reduced. So themobility of crude oil is greatly enhanced.3. It is approved that it is the metabolites that decrease the viscosity of crude oil. In the process of decreasing viscosity, bacteria have a cooperative effect on the metabolites. The mechanism of decreasing oil viscosity is a complex biochemical process that microbe operate company of bacteria.4. The physical simulating experiments, which analyses the property of produced water by microbial flooding, make clear that the existence of microbe can largely increase the contents of volatile fatty acid in produced water, which can effectively enhances the acidity of produced water, reduces surface tension of water and interfacial tension between oil and water.In a word, the relationship between metabolism of microbe and enhanced oil recovery mainly manifests in the property improvement of flow in porous media. So the effects of microbe on the wettability of rock surface and the properties of crude oil and water are the crucial techniques in the MEOR. Through the three aspects above mentioned, the biochemical mechanism the MEOR can be interpreted.