Tensor 3D interpretation of CSRMT data with novel high-frequency sources considering displacement currents and anisotropy

考虑位移电流和各向异性的新型高频源对 CSRMT 数据的张量 3D 解释

• 批准号: 444968617
• 负责人: Professor Dr. Bülent Tezkan
• 金额: --
• 依托单位: Institut für Geophysik und Meteorologie
• 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/444968617?language=en
• 关键词: Tensor; 3D; interpretation; CSRMT; data

Electromagnetic and electric methods of applied geophysics are commonly used to study the conductivity structure of the shallow subsurface. In the past decades the radio-magnetotelluric (RMT) method has gained popularity and was successfully applied to various environmental, engineering, and other exploration problems. The conventional RMT method uses military and civilian radio transmitters broadcasting in the frequency range between 10 kHz and 1MHz. A significant disadvantage of the traditional RMT method is the lack of robust high-frequency sources in remote areas. Another drawback is the fact that there are no radio-transmitters broadcasting at frequencies below 10 kHz which limits the penetration depth. To overcome these limitations, active and controlled-sources can be used instead of depending on remote radio-transmitter signals (CSRMT method, 1 kHz –1MHz). In several studies, the CSRMT method was successfully applied to shallow exploration. Both, horizontal magnetic (HMD) and horizontal electric dipoles (HED) were used. Besides logistical and technical advantages and disadvantages, these sources generate different modes of currents in the ground and have different spatial-temporal shapes leading to different sensitivity patterns. As a consequence, different sources have a different resolving power regarding the subsurface conductivity structures and can be utilized to derive improved anisotropic models of the subsurface. Currently, no systematic and elaborate comparative studies of such CSRMT sources exist for the frequency band of 1 kHz –1 MHz, including 3D numerical modeling and advanced field experiments. To tackle this gap in EM exploration, we propose the following objectives: (1) to develop source field strategies for optimal CSRMT surveying; our well-tested HED source will be further developed into VMD and HMD; (2) to derive improved subsurface models a novel 3D CSRMT modelling and inversion - based on the well-established ModEMM package - will be extended to all sources; (3) to take into account the displacement currents and (4) to develop the quasi-static ModEMM code further to consider the anisotropy (5) to validate the new sources, novel field experiments at two selected sites in Russia will be conducted.Analytical and numerical simulations will be used to optimize surveying strategies and to study the resolution power of different sources. Existing robust CSRMT processing software will be used to derive full impedance tensor and tipper transfer functions. Subsequently, the field data will be inverted in 3D using the proposed improvements and implementations in the ModEMM algorithm. Accompanying sensitivity studies will validate the resolving power of the considered sources and quantify the improvements on the models, particularly with respect to anisotropy.

电磁性藻类通常是研究电导率的数十年。传统RMT方法的10 kHz和1MHz之间的范围是偏远地区缺乏强大的高频源，可以根据远程射线射击信号（CSRMT方法，1 kHz –1MHz）来使用主动和控制d-sources。缺点，导致不同的空间形状。建模和高级现场经验。扩展到所有来源；为了优化研究，研究的源是完全阻抗和尖端的尖端功能。