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研究多相流动电磁波成像测井要涉及到两个物理基础问题 :一是油井中电磁波的传播特性 ,二是油井中流体介质的电磁性质。首先 ,采用场分析的方法 ,分析井内套管和流体介质对电磁波传播的影响。油井内的套管是钢铁质圆管 ,对电磁波的传播将产生限制和引导作用 ;油井内流体介质的电性质将决定导波的传播常数 ,影响电磁场在井的轴向上和横向上的分布状态和波的传播特性。通过研究提出了由于井内流体为有耗媒质 ,油井构成的导波系统不同于一般的圆波导 ,可以传播高频或低频电磁波的新观点。其次 ,从物理机理出发 ,对油、气与水的介电特性和导电特性差异进行分析 ,指出油井内混合流体的电性质不仅与各相流体的电性参数有关 ,而且与流体的流动速度、各相含量、分布状态以及测量电磁场有关。研究结果不仅论证了电磁波成像测井具有坚实的物理基础 ,而且明确了正确测量和显示井内流体流动截面必须合理选择电磁波的工作模式和频率。
Research on multiphase mobile electromagnetic imaging logging involves two physical basis questions: one is the propagation characteristics of electromagnetic waves in the well, and the other is the electromagnetic properties of the fluid medium in the well. Firstly, the field analysis method is used to analyze the influence of casing and fluid medium on electromagnetic wave propagation. The casing in the oil well is a steel tube that restricts and guides the propagation of the electromagnetic wave. The electrical properties of the fluid medium in the well will determine the propagation constant of the guided wave and affect the axial and lateral distribution of the electromagnetic field Status and wave propagation characteristics. Through the research, it is put forward that the fluid in the well is a lossy medium, and the oil well is different from the ordinary circular waveguide in that it can propagate the high frequency or low frequency electromagnetic wave. Secondly, based on the physical mechanism, the differences between the dielectric and electrical conductivity of oil, gas and water are analyzed. It is pointed out that the electrical properties of mixed fluids in oil well are not only related to the electrical parameters of each phase fluid, but also to the fluid flow velocity, The content of each phase, the distribution of state and the measurement of electromagnetic fields. The results not only demonstrate that electromagnetic imaging logging has a solid physical foundation, but also make it clear that the proper working mode and frequency of the electromagnetic wave must be selected reasonably for correctly measuring and displaying the cross-section of the fluid in the well.