多相流动电磁波成像测井基础研究

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。

A fundamental study on electromagnetic wave imaging logging in multiphase flow

The physical fundamentals of electromagnetic wave imaging logging in multiphase flow deal with the wave propagating characteristics and the fluid electromagnetic properties in oil wells. In this paper, the effects of the casing and the fluid media on the electromagnetic wave propagation in oil wells are studied and discussed following the field analysis. In an oil well, the casing is a steel circular pipe, and it would confine and guide the electromagnetic wave propagating; and the electric properties of the fluid media would determine the propagation factor of the guided wave and affect the distribution state of the electromagnetic field. A new standpoint produced from the study is that the guided wave system in the oil well is different from the normal circular wave guide, as the fluid is a conductive medium, and it allows the higher or lower frequency waves to propagate. From physical principle, the electric property differences among oil, gas, and water are analyzed, and it is pointed that the electric properties of their mixture in oil wells are not only determined by their electric parameters, but also related to the mixture flow velocity, concentration and distribution state of each phase, and the measured electromagnetic field. At the end, the study comes to the conclusion that the physical fundamentals of electromagnetic wave imaging logging are strong, and it is necessary to select the wave working mode and frequency carefully for measuring and displaying the multiphase flowing section in oil wells.electromagneticwave propagatio