提高低渗透油藏采收率的电源技术研究

发布时间：2019-02-18 07:49

【摘要】：外加直流电场提高原油采收率是近些年提高原油采收率的一种新技术,油气资源短缺一直都是世界各国面临的一大难题,而国内各大高渗透油田相继进入高含水期,而新探明油藏大多为低渗透油藏,原油开采方式难以满足需要,因此利用外加电场提高采收率有很广阔的发展潜力。本文在电渗理论的基础上搭建了外加电场作用下缝隙介质中两相流数学模型,推导出两相流的有限元方程,并利用COMSOL Multiphysics耦合软件进行有限元方法求解,从理论上分析了含水饱和度与水相相对渗透率在相渗曲线上的关系,讨论了外加电场存在时含水饱和度比无电场存在时更低的现象,并且验证了外加电场作用下缝隙介质中两相流数学模型的正确性。本文细致分析了外加电场存在情况下缝隙媒介模块中含水饱和度的变化趋势,构建了外加电场作用下不同缝隙宽度、不同缝隙数量和不同缝隙结构的缝隙媒介模块,并进行数值模拟及分析,研究结论表明,所施加电场可使缝隙介质模块中含水饱和度下降;缝隙媒介模块的含水饱和度随缝隙宽度的减小而下降,则缝隙媒介模块渗透率越低所受施加电场影响越大;而且所施加电场对缝隙数量越少和连通度越小的模型中含水饱和度影响越大。通过深入研究发现,在0~240V范围内,当外加直流电场为160V时电场在各缝隙模型中产生的效果最显著,两相流模块内含水饱和度最小,含油饱和度最大。根据数值模拟结果,把160V当作稳压直流电源输出的设计要求,结合Buck电路,软开关技术及双闭环控制电路进行稳压直流电源的设计,在仿真软件MATLAB中进行仿真与验证,得到可靠输出的直流电场。
[Abstract]:In recent years, increasing oil recovery by adding direct current electric field is a new technology to improve oil recovery. The shortage of oil and gas resources has always been a big problem facing countries all over the world, and the major domestic high permeability oilfields have entered into high water cut period one after another. However, most of the newly proved reservoirs are low permeability reservoirs, so it is difficult to meet the needs of crude oil production, so it has a broad development potential to improve oil recovery by using external electric field. On the basis of electroosmotic theory, the mathematical model of two-phase flow in slot medium under the action of external electric field is built, the finite element equation of two-phase flow is derived, and the finite element method is solved by using COMSOL Multiphysics coupling software. The relationship between water saturation and relative permeability of water phase on the phase permeability curve is analyzed theoretically. The phenomenon that the water saturation is lower in the presence of external electric field than in the absence of electric field is discussed. The mathematical model of two-phase flow in slit medium under the action of external electric field is verified. In this paper, the variation trend of water saturation in gap media module under the condition of external electric field is analyzed in detail, and the slot media module with different gap width, different slot number and different slot structure under the action of external electric field is constructed. The numerical simulation and analysis show that the applied electric field can decrease the water saturation in the slot dielectric module. The water saturation of gap media module decreases with the decrease of gap width, and the lower the permeability of gap medium module is, the greater the effect of applied electric field is on the permeability of slot media module. Moreover, the effect of the applied electric field on the water saturation in the model with less gap number and less connectivity is greater. It is found that when the applied DC field is 160 V, the effect of the electric field in each slot model is the most significant, the water saturation in the two-phase flow module is the least, and the oil saturation is the largest in the two-phase flow module. According to the results of numerical simulation, 160V is regarded as the design requirement of the output of DC power supply with stable voltage, and the design of stabilized DC power supply is carried out by combining Buck circuit, soft switch technology and double closed-loop control circuit. The simulation and verification are carried out in the simulation software MATLAB. A reliable output DC field is obtained.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE348;TN86

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