Ability of the magnetotelluric method to image a deep conductor: Exploration of a supercritical geothermal system
Ability of the magnetotelluric method to image a deep conductor: Exploration of a supercritical geothermal system
复制标题
DOI：
10.1016/j.geothermics.2021.102205
复制
发表时间：
2021-11
期刊：
影响因子：
3.9
通讯作者：
K. Ishizu;Y. Ogawa;T. Mogi;Y. Yamaya;T. Uchida
中科院分区：
文献类型：
--
作者：
K. Ishizu;Y. Ogawa;T. Mogi;Y. Yamaya;T. Uchida
超临界条件下的圈闭流体是潜在的高产地热资源。利用大地电磁（MT）方法，这些超临界流体可以成像为深导体（bbb20 ~ 2km）。然而，深部导体的MT成像强烈依赖于导体的几何形状和上覆的粘土层。MT方法成像深层导体的能力需要澄清，以了解MT在探索超临界流体方面的有用性，并准确地将成像的导体与超临界流体联系起来。在这项研究中，我们基于日本东北部Kakkonda地区超临界地热系统的概念电阻率模型，利用数值试验研究了超临界流体深层导体的MT成像。实验结果表明，MT方法能够对超临界流体的深层导体进行成像。然而，我们发现成像的深层导体的形状和电阻率值可能与真实导体的形状和电阻率值存在显着差异。具体来说，如果用MT反演成像一个深的垂直细长导体，需要注意的是，实际底部在水平方向上可能比成像尺寸宽得多。
Fluids trapped under supercritical conditions are potential geothermal resources yielding high well-productivity. These supercritical fluids may be imaged as deep conductors (> 2km depth) using the magnetotelluric (MT) method. However, MT imaging of a deep conductor is strongly dependent on the conductor geometries and the overlying clay layers. The ability of the MT method to image a deep conductor needs clarification to understand the usefulness of MT for exploring supercritical fluids and accurately relate the imaged conductor to supercritical fluids. In this study, we investigated MT imaging of a deep conductor of supercritical fluids using numerical tests, based on a conceptual resistivity model for a supercritical geothermal system in the Kakkonda area, northeast Japan. The test result showed that the MT method was able to image the deep conductor of supercritical fluids. However, we found that the shape and resistivity value of the imaged deep conductor might significantly differ from those of the true conductor. Specifically, if a deep vertically elongated conductor is imaged by MT inversion, it is necessary to be aware that the actual bottom part may be much wider in the horizontal directions than the imaged size.