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Development of Exploration System for Three-Dimensional Temperature Distribution Using Resistivity

利用电阻率进行三维温度分布探测系统的开发

基本信息

批准号：
10555351
负责人：
OHMI Michito
金额：
$ 8.06万
依托单位：
Kumamoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

We examined an exploration system for estimating a three-dimensional temperature distribution in geothermal field through resistivity distribution in the shallow and deep depths. The resistivity data were obtained by electrical exploration and Magneto-Telluric (MT) method. Mt. Aso, which is a typical active volcano and situated in central Kyushu, was chosen as the study site. The main results are summarized as follows.(1) Fault shape concerning width, dip direction, and dip angle can be estimated from spatial distribution of radon concentrations through combination of a numerical simulation for the movement of radon and the calculation method of number of radon atoms. The radon concentrations on a fault, which has a role of conduit for hydrothermal fluids, show large temporal changes attributable to the activity of volcanic earthquakes.(2) We have constructed the estimation and interpretation methods of fracture orientation through a combination of satellite-image derived lineaments, d … More igital elevation model data, and digital geologic map. These methods can be used to infer distribution pattern of fractures that have effect on flow path of hydrothermal fluids.(3) A new method using neural network and geostatistics was applied to estimate distribution of subsurface temperatures from geothermal investigation loggings. In spite of the restricted quantity of sample data, the interpolation results revealed high temperature zones and convection patterns of hydrothermal fluids.(4) Electrical exploration clarified that the resistivity near the ground surface tends to decrease upon a fault which moved recently. The resistivity distribution in the deep depths of a fault, which is obtained by MT method, is not homogeneous, and the resistivity in largely fractured zones is specially low. Because the resistivity distributions between TE mode and TM mode are quite different, the resistivity of Mt. Aso is thought to have strong anisotropic behavior.(5) A general relation that the portion with higher temperature has higher resistivity was found through the examination of the resistivity obtained by MT method and the temperature estimated by a finite element method. Furthermore, the resistivity under the discharge zone of hydrothermal fluids was found to be lower than the other areas with the same temperature. Less

本文研究了一种利用浅层和深层电阻率分布估计地热田三维温度分布的勘探系统。电阻率资料采用电法勘探和大地电磁法获得。山位于九州中部的阿索是一座典型的活火山，被选为研究地点。主要研究结果如下。(1)通过氡运动的数值模拟和氡原子数的计算方法相结合，可以从氡浓度的空间分布估计断层的宽度、倾向和倾角等形状。氡浓度的断层，这有一个管道的作用，热液流体，显示大的时间变化归因于火山地震的活动。(2)本文建立了利用卫星影像提取的线性构造、三维地震资料和地震资料进行裂缝方位估计和解释的方法。 ...更多信息数字高程模型数据和数字地质图。这些方法可以用来推断影响热液流体流动路径的裂缝分布模式。(3)将神经网络和地质统计学相结合，提出了一种利用地热调查资料估算地下温度分布的新方法。尽管样本数据有限，但插值结果揭示了热液流体的高温区和对流模式。(4)电法勘探表明，近地表的电阻率往往会降低后，最近移动的断层。大地电磁测深法在断层深部的电阻率分布是不均匀的，特别是在断裂破碎带电阻率较低。由于TE模式和TM模式的电阻率分布有很大的不同，因此Mt.阿索被认为具有强的各向异性行为。(5)通过对MT法测得的电阻率和有限元法估算的温度的检验，发现了温度高的部位电阻率高的一般关系。此外，在热液流体放电区的电阻率被发现低于其他地区具有相同的温度。少