Selectively Activation And Molecular Analysis Of Stratal Microorganism In Petroleum Reservoirs

Indigenous microorganism in petroleum reservoirs is better fit for the extreme enviroment than extraneous microorganism. Nowadays, ASMEOR (Activation of Stratal Microflora for Enhancement of Oil Recovery, ASMEOR) is an active aspect in MEOR (Microbial Enhanced Oil Recovery, MEOR) domain, which research mainly on mechanism of MEOR, the change of functional bacteria, analysis of microbial metabolic products and their affection on physical and chemical properties of oil and water, while there's little information about the factors which affect the growth and metabolization of stratal microorganism, the change of the structure of dominant microbial population during activation and the adsorption of nutrition.The thesis consists of seven parts: the first part is literature summarization; the second part is the analysis of community structure of indigenous microorganisms; the third part is researching factors of activation process; the fourth part is physical simulation study on indigenous microbial flooding; the fifth part is studying static and dynamic absorption of nourishment used in ASMEOR on quartzite sand; the sixth part is application of molecular ecology in ASMEOR ;the seventh part is the conclusions.Based on the analysis of the change of dominant microbial population during activation, the adsorption of nutrition, DGGE ( Denaturing Gradient Gel Electrophoresis, DGGE) bands and PCR (Polymerase Chain Reaction, PCR),PCR sequencing, the objectives of this study are to screen out best selective-activating agent for Block zhan3, identify important factors which affect the growth and metabolization of stratal microorganism, sudy the adsorption of nutrition. Furturemore, molecular ecology methods were used to investigate the change of microbial community during activation. The main results are summarized as follows: 1 Analysis of community structure of indigenous microorganismsWith selected media, the community structure of indigenous microorganisms in produced water and injected water samples at Block Zhan3 in Shengli Oilfield was analyzed with MPN and microscope methods. The results showed that the density of all bacteria and beneficial bacteria(HOB- Hydrocarbon Oxidating Bacteria, MPB- Methane-Producing Bacteria and DNB- Denitrifying Bacteria)was low but the number of SRB( Sulfate Reducing Bacteria, SRB) reached 102 cell/mL. It's possible to selectively activate the beneficial stratal microorganisms and inhibit the detrimental ones in the reservoir by adding activation nutrition.2 Factors of activation process and physical simulation study on indigenous microbial flooding1)Based on the anysis of the density of all bacteria, the change of pH, surface tension and Ac-, best main component of activation nutrition was screened from corn steep liquor,glucose and cane sugar. The results showed that the activation effect of corn steep liquor and glucose was better than cane sugar. corn steep liquor is a byproduct of corn processing, which is beneficial to resource utilizationg.Therefore, corn steep liquor is the best of the three sources.2)Based on the analysis of the density of all bacteria, the change of surface tension and Ac- before and after activation, the optional activation nutrition components were studied by core sandpack experiments using"one-variable-at-a-time"method. The results were as follows: the optional concentration range of corn steep liquor was 1 %~2 %. Activation effect was bad when the concentration of corn steep liquor was low, while enhancement effect to the density of all bacteria and surface tension were changed slight when the concentration of corn steep liquor is higher than 1%; the optional concentration range of nitrate was 0.1%~0.2 %; KNO3 was better than NaNO3 and NH4NO3, because the promoting effect of K~+ on the growth of bacteria and the decreasing of pH with the adding of NH4NO3.3)Based on the analysisi of the change of surface tension and the community structure of indigenous microorganisms, influence of pressure and porous media on the growth and metabolization of stratal microorganism was studied. The influence of porous media was notable compared to pressure.4)The result of physical simulation study on indigenous microbial flooding showed that the oil recovery from residual oil has been increased by above 6% after 15 days culture by using the optional activation nutrition.3 Static and dynamic absorption of nourishment used in ASMEOR on quartzite sandUnder simulative formation conditions, the static and dynamic absorption of nourishment components (glucose, potassium nitrate and potassium dihydrogen phosphate) usually used in microbial enhanced oil recovery on quartzite sand were studied by methods of dipping in and mass balance. The results showed that there was little difference between static absorptive captive of individual component and its dynamic holdup. Among the three components, glucose's static absorptive captive and dynamic holdup were maximal, its static absorptive captive was 0.85mg/g, absorptive captive of potassium nitrate and that of potassium dihydrogen phosphate were very little, only about 0.1mg/g. And in the dynamic experiments, individual component concentration in effluent liquid was approach to that in inject liquid when the nourishment volume injected reached 1.5 PV(porosity volume), its concentration in effluent liquid was close to 0 after shifting to water flooding about 2PV, which suggested that dynamic absorption of the three components on sand core was slight.4 Application of molecular ecology in ASMEOR1)Based on the analysis of the number and lightness of DGGE bands, the change of the microbial community diversity was studied. The results showed that the species number and total quantity of dominant microbial population were not abundant under oil reservoil conditions; After injecting activation agent, some bacteria growded and reproduced quickly along with the enhancement of nutrition condition. At one time, the structure of dominant microbial population changed. Under high pressure condition(10 MPa), the number of DGGE bands was fewer compared to under atmospheric pressure, which indicated that the microbial species seasoned with high pressure condition was few. And the rapidity of increase of DGGE bands was slower under high pressure condition.In late activation period, the change of DGGE bands was slight, which indicated that the structure of dominant microbial population readjusted successfully and reached new dynamic balance.2) Based on the methods of DGGE and PCR sequencing, the change of the structure of dominant microbial population during activation was studied. The result showed that: After activation, species number of dominant microbial population increased, and the structure of dominant microbial population obviously changed. Before activation, the main bacteria was belong to Bacillales. After injecting activation agent, the species of Proteobacteria increased. Under different pressure condition,the quantity of stratal microorganism showed obvious differences.