Interpretation of controlled source radiomagnetotelluric data in the frequency range 1 kHz - 1 MHz using multidimensional conductivity models

使用多维电导率模型解释 1 kHz - 1 MHz 频率范围内的受控源无线电大地电磁数据

• 批准号: 389154291
• 负责人: Professor Dr. Bülent Tezkan
• 金额: --
• 依托单位: Russian Foundation for Basic Research
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/389154291?language=en
• 关键词: Interpretation; controlled; source; radiomagnetotelluric; data

Controlled Source Radiomagnetotellurics (CSRMT) is a new and innovative electromagnetic method for shallow subsurface investigations down to roughly 100 m depth depending on the subsurface resistivity. In this project, tensor CSRMT measurements will be realized for the first time in the extended frequency range from 1 kHz to 1 MHz using a prolonged electric dipole source. Two survey will be conducted on two selected test areas in Russia. CSRMT far field data using such an extended frequency range and dipole source will also be interpreted for the first time by a 3D inversion. A rectangular signal with base frequencies between 0.1 kHz and 150 kHz will be injected through two approximately 700 m long grounded electric dipoles located perpendicular to each other. Time series of the electric and magnetic fields in the far and near field of the transmitter at spatially distributed receiver-locations will be observed. Full impedance and tipper transfer functions will be derived using a bivariate time series analysis. The spatially distributed far field CSRMT data will be interpreted by 2D and 3D inversion calculations. Conventional RMT measurements will be carried out during the time the transmitter is not active to increase data coverage. The derived conductivity 3D CSRMT model of the far field and the model derived from the RMT data will then be used to interpret the transfer functions of the near field by using the trial and error approach and 3D forward calculations. The investigated area close to St. Petersburg is a landfill area where the aquifer contamination will be investigated, whereas the survey area close to Moscow is a paleo-valley in which local high resistive sand lenses are embedded. These paleo-valleys are associated with deposits of mineral resources. Previous geophysical measurements and modellings (DC, RMT & Seismic) on these survey areas will be used as constraints in the multidimensional CSRMT modeling. Both targets are in a depth of about 15m and can be ideally detected by the CSRMT method.

可控源大地电磁法(CSRMT)是一种新的、创新的电磁方法，可根据地下电阻率的不同，进行深至约100米的浅层地下探测。在本项目中，将首次使用延长的电偶极子源在1 kHz到1 MHz的扩展频率范围内实现张量CSRMT测量。两项调查将在俄罗斯选定的两个试验区进行。使用这种扩展频率范围和偶极子源的CSRMT远场数据也将首次通过三维反演进行解释。基频在0.1 kHz到150 kHz之间的矩形信号将通过两个相互垂直的大约700米长的接地电偶极子注入。将观测空间分布的接收器位置处发射机远场和近场中的电场和磁场的时间序列。全阻抗和自卸车传递函数将使用双变量时间序列分析得到。空间分布的远场CSRMT数据将通过二维和三维反演计算来解释。传统的RMT测量将在发射机不活动期间进行，以增加数据覆盖范围。推导出的远场电导率3D CSRMT模型和由RMT数据导出的模型将通过试错法和三维正演计算来解释近场的传递函数。圣彼得堡附近的调查区是将调查含水层污染的垃圾填埋区，而莫斯科附近的调查区是一个埋藏着当地高阻砂岩透镜的古山谷。这些古山谷与矿产资源矿床有关。这些调查区以前的地球物理测量和建模(DC、RMT和地震)将被用作多维CSRMT建模的约束。这两个目标都在大约15米的深度，可以理想地用CSRMT方法进行探测。