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.

应用地球物理的电磁和电学方法常用于研究浅层地下的电导率结构。在过去的几十年里，无线电大地电磁（RMT）方法得到了普及，并成功地应用于各种环境，工程和其他勘探问题。传统的RMT方法使用军用和民用无线电发射机在10 kHz和1 MHz之间的频率范围内进行广播。传统的RMT方法的一个显著缺点是在偏远地区缺乏鲁棒的高频源。另一个缺点是没有以低于10 kHz的频率进行广播的无线电发射机，这限制了穿透深度。为了克服这些限制，可以使用有源和受控源，而不是依赖于远程无线电发射机信号（CSRMT方法，1 kHz-1 MHz）。在一些研究中，CSRMT方法成功地应用于浅层勘探。使用水平磁偶极子（HMD）和水平电偶极子（HED）两者。 除了后勤和技术方面的优点和缺点外，这些来源在地面产生不同模式的电流，并具有不同的时空形状，导致不同的敏感性模式。因此，不同的源具有关于地下电导率结构的不同的分辨能力，并且可以用于导出地下的改进的各向异性模型。目前，没有系统的和详细的比较研究，这样的CSRMT源存在的频率为1 kHz-1 MHz，包括三维数值模拟和先进的现场实验。为了解决EM勘探中的这一差距，我们提出了以下目标：（1）开发用于最佳CSRMT测量的源场策略;我们经过良好测试的HED源将进一步发展为VMD和HMD;（2）为了获得改进的地下模型，将基于成熟的ModEMM包的新型3D CSRMT建模和反演扩展到所有源;（3）考虑到位移流;（4）开发准静态ModEMM代码以进一步考虑各向异性;（5）为了验证新震源，将在俄罗斯的两个选定地点进行新的现场实验。分析和数值模拟将用于优化勘测策略并研究不同震源的分辨率。现有的强大的CSRMT处理软件将用于推导全阻抗张量和倾翻器传递函数。随后，现场数据将在3D中使用ModEMM算法中提出的改进和实现进行反演。伴随的敏感性研究将验证所考虑的源的分辨能力，并量化模型的改进，特别是在各向异性方面。