Mapping Upflow Zones With The Anomalous Geometry Of A Shallow Conductor At The Las Tres Virgenes Geothermal Field, Mexico

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Conference Paper: Mapping Upflow Zones With The Anomalous Geometry Of A Shallow Conductor At The Las Tres Virgenes Geothermal Field, Mexico

Abstract
The electrical resistivity structure, down to an average depth of 650 m, is determined under the Las Tres Virgenes geothermal zone from more than 100 vertical electric soundings (VES) and transient electromagnetic (TEM) soundings. The explored depths lie above the geothermal reservoir, which is located in fractured granitic rocks at a depth of 1200 m. The dominant feature in the data is a conductor associated with the regional aquifer with an average thickness of 300 m. By stitching together 1-D Occam's inversions several smooth sections are constructed. They are formed by imposing a smooth condition to the lateral variation of resistivity, by considering the shift-correction of theVES data as a variable, and by jointly interpreting the data from both geophysical methods. This procedure reduces the ambiguity in the interpretation produced by a number of perturbing sources. An anomalous zone, located at the base of the regional conductor, is identified by the increased conductor's thickness and eventual disappearance of its base. This zones is interpreted as an upflow zone where fracture permeability perturbs the impermeable rock unit that separates the shallow regional aquifer from the deep geothermal reservoir, allowing the vertical flow of geothermal fluids.

Author 
Carlos Flores








Published 
GRC, 2003





DOI 
Not Provided
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Citation

Carlos Flores. 2003. Mapping Upflow Zones With The Anomalous Geometry Of A Shallow Conductor At The Las Tres Virgenes Geothermal Field, Mexico. In: (!) ; (!) ; (!) . (!) : GRC; p. (!)