3D Magnetotelluric characterization of the COSO GeothermalField
Knowledge of the subsurface electrical resistivity/conductivity can contribute to a better understanding of complex hydrothermal systems, typified by Coso geothermal field, through mapping the geometry (bounds and controlling structures) over existing production. Three-dimensional magnetotelluric (MT) inversion is now an emerging technology for characterizing the resistivity structures of complex geothermal systems. The method appears to hold great promise, but histories exploiting truly 3D inversion that demonstrate the advantages that can be gained by acquiring and analyzing MT data in three dimensions are still few in number. This project will address said issue, by applying 3D MT forward modeling and inversion to a MT data set acquired over the Coso geothermal field. The goal of the project is to provide the capability to image large geothermal reservoirs in a single self-consistent model. Initial analysis of the Coso MT data has been carried out using 2D MT imaging technology to construct an initial 3D resistivity model from a series of 2D resistivity images obtained using the inline electric field measurements (Zxy impedance elements) along different measurement transects. This model will be subsequently refined through a 3D inversion process. The initial 3D resistivity model clearly shows the controlling geological structures possibly influencing well production at Coso. The field data however, also show clear three dimensionality below 1 Hz, demonstrating the limitations of 2D resistivity imaging. The 3D MT predicted data arising from this starting model show good correspondence in dominant components of the impedance tensor (Zxy and Zyx) above 1Hz. Below 1 Hz there is significant differences between the field data and the 2D model data.
- Research Organization:
- Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
- Sponsoring Organization:
- USDOE. Assistant Secretary for Energy Efficiency andRenewable Energy. Geothermal Program Office. Geothermal Research; USDepartment of Defense. US Navy Contract N68936-03-P-0303; QuantecGeoscience Inc. Energy and Geoscience Institute
- DOE Contract Number:
- AC02-05CH11231
- OSTI ID:
- 891038
- Report Number(s):
- LBNL--58328; BnR: EB4005010
- Country of Publication:
- United States
- Language:
- English
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