Utah FORGE: Phase 3 Magnetotelluric (MT) Data

New high-quality tensor MT data at 122 sites, including the vertical magnetic field and utilizing ultra-remote referencing, have been acquired over the Utah FORGE project area. The results will be used to delineate the densities of faults and fractures in crystalline basement rocks, to define the heat sources, and to derive baseline 3D resistivity structure for later MT monitoring of temporal changes in resistivity structure following well stimulation in the EGS reservoir. There are three files here related to Utah FORGE magnetotelluric (MT) data acquisition and processing. The FORGE MT EDIs zip file contains the observed MT responses in industry-standard EDI format. For each site, there is an EDI response file that utilized a local independent reference for noise cancellation, and a file that utilized a distant reference cancelling noise associated with the DC transmission line of the Delta IPP passing down the west side of Milford Valley. These two site files could be merged as appropriate. The FORGE Model Cell Center file contains the model volume of the 3D Forge MT inversion for characterizing the resistivity structure in the project area. It was derived using finite element inversion methodology described in Wannamaker et al, in the attached FORGE Phase3 Geophysics paper, from the MT observation EDI files. It is ASCII format (.dat) and entries are defined at top of the file in a simple x-y-z-Rho listing in UTM coordinates. The element layers drape the topography so the Rho value layers are not purely horizontal slices. This greatly simplifies the listing.

在犹他州FORGE项目区域内，采集得到122个测点的高质量张量大地电磁（Magnetotelluric, MT）数据，该数据涵盖垂直磁场分量，并采用超远参考降噪技术。本次采集所得数据将用于刻画结晶基底岩石中断层与裂隙的发育密度、界定项目区域内的热源，并构建三维电阻率结构基准模型，以支撑后续针对增强型地热系统（Enhanced Geothermal System, EGS）储层压裂作业后电阻率结构时序变化的大地电磁监测工作。本次数据集包含三份与犹他州FORGE大地电磁（MT）数据采集及处理相关的文件：FORGE MT EDIs压缩包内含行业标准EDI格式的实测大地电磁响应数据。每个测点对应两类EDI响应文件：一类采用本地独立参考源开展噪声压制，另一类采用远端参考源，以消除米尔福德谷西侧Delta IPP直流输电线路引发的电磁噪声干扰，上述两类测点文件可根据实际需求进行合并。FORGE模型单元中心文件包含用于刻画项目区域电阻率结构的三维FORGE大地电磁反演模型体，该模型基于本次采集的大地电磁观测EDI文件，采用Wannamaker等人在附件《FORGE第三期地球物理学》论文中所述的有限元反演方法构建。该文件采用ASCII格式（.dat），文件头部定义了UTM坐标系下的简易x-y-z-Rho列表格式，所有数据条目均遵循此规范。模型单元层贴合地形起伏，因此电阻率（Rho）值图层并非严格水平切片，这大幅简化了数据列表的排布逻辑。