Visualized experiments is applied to study mechanisms of crude oil consuming microorganisms to enhance oil recovery. It is discovered that they have the tendency to migrate directionally towards and eventually become closely contact with crude oil. This "local enrichment" phenomenon consequently results in a high concentration of microbes around crude oil and hence forms the foundation for enhancing oil recovery using crude oil consuming microorganisms. It is found that the concentration of the colony around the carbon source is the highest, which is 5 similar to 6 quantity degree higher than that of the other places. The further, the thinner. The distribution of metabolic product concentration conforms to that of the thallus concentration. The simulated microscopic experiments manifest that the coordinated action of high concentration microbes and their metabolites results in varieties of mechanisms to startup residual oil, such as peeling off oil membranes, peeling off oil beads, blocking big pores, emulsifying and starting up residual oil and improving the wettability of the mortise wall, etc. The new technology of microbe waterflooding and breathing combination was applied in the field experiments. The wellhead pressure and the metabolic gas content all increased obviously and continuously in the shut up period. After the wells started up, it was observed with many analyzing method that the crude oil fluidity improved obviously, and the live microbes, CO, and organic acid content all increased. All the above conditions are benefit for enhancing oil recovery, and the effect of oil-booster and precipitation was obvious over a long period of time.

In order to improve the sweeping coefficient of injected water and therefore to reach to the objective of deep profile control,the molecular gel system is used,which is composed of polyarylamide and cross-linking agent of suitable concentration.The residual resistance coefficient of the system measured through the core experiments reaches to 83.5.And the oil-displacement experiments with the combined slug of the molecular gel with polymer solution through the vertical heterogeneous cores are carried out,it is shown that recovery factor can be increased by more than 30% based on initial water flooding.The field test also shows that the oil-displacement system can greatly improve the water injection profile of injection wells,decrease the water cut of oil production wells and enhance oil production.

Based on the analysis of the bacterial chemotaxis, the percolation theory was introduced and a micro emulation method was proposed for the bacterial distribution in the porous medium. Comparing with measuring results of the experiment, this method could simulate well the bacterial concentration distribution in porous medium. Finally, some potencial advices were given for the futher using of this method.

SMA hard-gel sealing agent is made up of host-compound,cross-linking agent and delay agent.The gelation time of the hard-gel sealing agent can be controlled by adjusting the dose of the delay agent.The performance experiments of the gel are made with man-made cores,and the results show that the gelation time is 72 h at 50℃;The sealing ratio of the gel sealing agent is greater than 99.9%,and it is not also lower than 99.8% after the water of 50 PV is injected;The breakthrough pressure gradient is not lower than 3.4 MPa/m usually.The visual fracture-sealing experiment is made with glass sandpack column,and it is obviously observed that SMA hard-gel can effectively sealing the fractures,the sequential injected water changes its direction,and its swept area evidently increases.In the sealing experiments with long man-made cores, a great amount of SMA solution is injected,and fractures can be blocked for a long time,which improves the utilization efficiency of the sequential injected water and oil recovery factor can been enhanced by 31.76% based on the recovery factor of initial water flooding.

应用可视化实验观测方法,对3种原油碳源微生物提高原油采收率的机理进行的研究发现,原油碳源微生物有向原油定向运移并直接接触原油的“自动寻的”功能,并使原油碳源处菌群高度富集。这种自动寻的运移是原油碳源微生物提高原油采收率的基础。实验发现,在任何时候,原油碳源处的菌浓度比其他各处高出5~6个数量级。距原油碳源越远,菌浓度越低,其代谢产物浓度分布规律与菌浓度分布规律相符。微观模拟实验表明,高浓度的菌群及其大量代谢产物协同作用于原油碳源有利于剩余油启动。依据所得规律,对应用原油碳源微生物提高采收率的生产模式提出了建议。

To develop a water block remover of low-cost,long-term effect,environmental protection and safety,and of being able to relieve the block caused by polymer near well-bore,the evaluation experiments were carried out indoors using the mixed strains separated from the polymer-bearing produced liquid in an oilfield.The mixed strains consist of pseudomonas sp.ML1,clostridia sp.ML2 and ML3.The static experiments with HPAM biodegradation,the oil-displacement experiments in the emulation micro-models,and manmade cores indicated that the microbes could degrade the long-chained high-molecular polymer,release the block near well-bore,improve the communication of the pores and channels and increase the productivity,thus improving the single-well production.The final oil recovery was increased by 11.9% on what has already been achieved with polymer flooding.The field test demonstrated that after the damage removal by using the microbes,the injection pressure of injectors reduced,the liquid production of producers increased,and the effective period was up to more than 540 days.

从某油田产出水中分离得到一株以原油为碳源的Pseudomonas sp.菌(假单孢菌),其化学趋向性运动能力中等,趋向性机理在本文中得以详细描述.在可视化模型实验中可看到微生物向油水界面处的有序运动,而在有效的营养物浓度梯度范围内,化学趋向性运移速度与距油水界面的距离无关,受温度的影响很大.并且在微观仿真模型实验中,可观察到细菌在孔隙壁和油、水三相交界处聚集,并讨论了该现象的形成原因及其对微生物采油的有利作用.

The effects of pore structure on the fractal dimension were studied. Based on the similar dimension,the method of measuring the fractal dimension was brought forward in natural low-permeable cores through traditional intrusive mercury data or image analysis,and the calculated formula for the dimension was achieved. By using the intrusive mercury data from natural cores,the curves were protracted and the fractal dimensions in porous media were calculated. In some formation segments,where there are only compaction and solution under pressure,the fractal dimension has diagenesis;while in other segments,the pore structures become more complicated due to intensive epigenesises,such as secondary quartz enlargement,recrystallization,and corrosion. Therefore there are several dimension values.

STP profile control hard-gel is made up of polyarylamide, cross-linking agent and retardant. The gel performance experiments were conducted with man-made cores, the gelation time was 72h at 55℃, the blocking coefficient was larger than 99.9% and it was not less than 99.8% after being flushed with 50 PV injected water. The breakthrough pressure gradient was not lower than 4.45MPa/m in high-permeability cores (5.62D) and it was 3.46MPa/m in low-permeability ones (0.57D), which shows some selectivity. Three high-permeability cores and low-permeability ones were connected in tandem, respectively; both were paralleled to form the heterogeneous model. The model was saturated with oil and profile controlling experiments were carried out, in which the total water-flood recovery was 24.3% in case of that no profile control agent was injected. The first, second and third high-permeability cores were sealed in turn by using the profile control agent, the total recovery reached 46.8%, (62.2%) and 69.1%, respectively, which indicated that the recovery could be further enhanced as the sealed depth increases.The application in the exploiting zone of Daqing Oilfield is apparently effective.

从某油田产出水中分离得到一株Pseudomons sp.菌,主要代谢产物是糖脂类表活剂,同时产少量低分子有机酸.在菌体局部富集实验中可观察到细菌由于化学趋向性而在油水界面处富集;在代谢产物局部富集实验中,肉眼可观察到由于在位繁殖效应,油水界面处水相的颜色变化,在不同距离处分别取样定量测定得到产物浓度分布梯度;并且在微观仿真模型中做微生物驱油实验,观察到菌体在孔隙壁和油、水三相交界处富集,研究微生物及其代谢产物的驱油机理,得到了一些有价值的结论.

The strong gel forming fluid STP is composed of HPAM (hydrolyzed polyacrylamide), redox crosslinker, and mixed lactic/propionic/acetic acid with a little amount of ethylene glycol added as retarder. The optimal gelation conditions are established as: pH 5.2, 55°C, and salinity < 7 g/L. The gelation time can be controlled in the range 12-144 hr through retarder dosage variation and the gelling fluid can be used in reservoirs of temperature 35°-80°C. A heterogeneous physical model comprising two parallel series of three oil-saturated cores each, a high and low permeable, is water flooded to water cut 98% and oil recovery 24.3% and then the 1st, the 2nd, and the 3rd high permeable cores are plugged by using gel STP and after every gel treatment the model is water flooded to watercut 98%. Thus, the deeper the gel placed the higher the oil recovery. The oil displacing mechanisms involved are discussed.

Bacteria taken the glycolipid surfactant as the main metabolic production and producing a little low-molecular organic acid simultaneously were selected to put on a piece of slide glass.The experiment showed that the bacteria became enrichment on the oil-water interface due to the chemotaxis.During experiments on bacteria in glass box,it could be seen with eyes that fluid muddy on the oil-water interface got thicker and thicker gradually,because of “breeding in situ”.The concentration distribution of the products of samples gotten from different distances from the interface was quantitatively measured.The result shows that there are concentration distribution gradients of products.The microbial oil_displacement experiments were programmed in emulation network models.It could be seen that bacteria were prior to entering into the three-phase boundary of pore wall,oil and water.The oil-displacement mechanisms of several techniques were studied,including emulsifying and starting up the remained oil,peeling the oil film off and altering the humidity of the orifice.The integration of these techniques is available for improving oil recovery.