Inversion of multi-source time domain electromagnetic data

多源时域电磁数据反演

• 批准号: 340409-2006
• 负责人: Oldenburg, Douglas
• 金额: $ 16.06万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=361995
• 关键词: Inversion; multi; source; time; domain

Electrical conductivity is a key physical property associated with mineral deposits, oil and gas, water, and environmental contaminants. Electromagnetic surveys have been devised to acquire data that are sensitive to the unknown conductivity. Typically, the electric and/or magnetic fields caused by a grounded dipole or a current loop source are recorded, and the practical difficulty is then to recover the 3D conductivity structure that caused these measured data. Previous research at the UBC Geophysical Inversion Facility has resulted in methodologies and software programs for inverting both frequency (FEM) and time domain (TEM) data when only a few transmitter sources are employed. The outcomes are in use at sponsoring companies. However, 3D inversion of TEM data is a computationally challenging task that increases with the number of transmitter locations, and current techniques are not viable for surveys using many transmitter locations. In this research we propose to develop robust and efficient 3D inversion methods for multi-source TEM data sets associated with airborne or ground surveys. An important  component of the research is to develop workflows and efficient strategies for handling these large data sets. We propose to develop practical software and work closely with industry sponsors to achieve this goal. Final codes will be distributed to the sponsors. First, Maxwell's equations will be reformulated in terms of electric and magnetic fields and the subsequent forward modeling matrix will be decomposed. The quasi-Newton methodology we developed earlier will be implemented. The beta-version of the code will be tested on synthetic and field data sets provided by sponsors, including ground and airborne surveys with multiple sources. Workflow and utility programs will be developed as testing progresses. A final inversion code (converted from MatLab into Fortran) will be delivered to sponsors, including GUI interfaces to run the codes, documentation, and workflow elements.

导电性是与矿藏、石油、天然气、水和环境污染物相关的关键物理性质。设计电磁测量是为了获取对未知电导率敏感的数据。通常，记录由接地偶极子或电流环源引起的电场和/或磁场，实际困难在于恢复产生这些测量数据的3D电导率结构。UBC地球物理反演设施之前的研究已经产生了在只使用少数发射机源时反演频率（FEM）和时域（TEM）数据的方法和软件程序。研究结果已在赞助公司得到应用。然而，TEM数据的三维反演是一项具有计算挑战性的任务，随着发射机位置的增加，目前的技术对于使用许多发射机位置的调查是不可行的。在这项研究中，我们建议开发与航空或地面调查相关的多源透射电镜数据集的鲁棒和有效的三维反演方法。该研究的一个重要组成部分是开发处理这些大型数据集的工作流程和有效策略。我们建议开发实用的软件，并与行业赞助商密切合作以实现这一目标。最终代码将分发给赞助商。首先，将麦克斯韦方程组以电场和磁场的形式重新表述，并对后续的正演建模矩阵进行分解。我们之前开发的准牛顿方法将被实现。该代码的beta版本将在赞助者提供的综合和实地数据集上进行测试，包括多种来源的地面和空中调查。工作流程和实用程序将随着测试的进行而开发。最终的反转代码（从MatLab转换为Fortran）将交付给发起人，包括用于运行代码、文档和工作流元素的GUI界面。