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On the study of electromagnetic prospecting using holographic imaging

全息成像电磁勘探研究

基本信息

批准号：
11650961
负责人：
MOGI Toru
金额：
$ 1.22万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650961/
关键词：
Electromagnetic prospecting 電磁探査ホログラフィックイメージング

项目摘要

The study was carried out to investigate the applicability of holographic imaging to the high resolution electromagnetic prospecting. I have been studying an applicability of the near-field holography theory to the time domain electromagnetic method. Resolution of the conventional holography depends on the wave length and is expected to same order of it. But, resolution of the near field holography does not relate to the wave length and is expected to less than 1/1000 of it.A high resolution prospecting means obtaining high accurate data. We should increase accuracy of time domain electromagnetic method, which is one for obtaining the data in a field, to increase resolution of the survey. I have been studying feature of the time domain method comparing other electromagnetic method and three dimensional modeling of the time domain data.A frequency domain method, like magnetotelluric method, tend to show less response to an anomaly at depth if low resistivity layer is situating at the surface. The depth of investigation of it tend to be much less than the skin depth of electromagnetic wave, which is usually using estimation of depth of investigation for frequency domain data. In time domain, the response time is only longer and the effect of low resistive layer at surface is less if the data obtain stably during the longer time.I have investigated an effect of three dimensional structure on the resistivity model assumed two dimensional (resistivity structure is uniform at vertical to the section). The anomaly situated beside the section and at the shallower depth is projecting at the deeper part of the two dimensional section. The projection appears in the time domain case similarly and we should develop three dimensional holographic modeling to avoid such effect.

研究了全息成像技术在高分辨率电磁勘探中的应用。我一直在研究近场全息理论对时域电磁法的适用性。传统全息术的分辨率与波长有关，一般要求与波长同量级，而近场全息术的分辨率与波长无关，一般要求小于波长的1/1000，高分辨率勘探意味着获得高精度的数据。时间域电磁法是一种野外采集资料的方法，要提高勘探分辨率，就必须提高其精度。通过对比其他电磁法和时间域数据三维建模方法，研究了时间域方法的特点，指出频率域方法如大地电磁法，在地表存在低阻层时，对深部异常的响应往往较弱。其探测深度往往远小于电磁波的趋肤深度，通常采用频率域数据的探测深度估计。在时间域中，如果数据在较长时间内稳定获得，响应时间只会更长，表面低阻层的影响较小。我研究了三维结构对假设二维的电阻率模型的影响（电阻率结构在垂直于剖面上是均匀的）。位于剖面旁边和较浅深度处的异常在二维剖面的较深部分突出。在时域情况下也会出现投影现象，应发展三维全息建模以避免这种影响。