A Geological And Geophysical Appraisal Of The Baca Geothermal Field, Valles Caldera, New Mexico
Journal Article: A Geological And Geophysical Appraisal Of The Baca Geothermal Field, Valles Caldera, New Mexico
AbstractThe Baca location #1 geothermal field is located in north-central New Mexico within the western half of the Plio-Pleistocene Valles Caldera. Steam and hot water are produced primarily from the northeast-trending Redondo Creek graben, where downhole temperatures exceed 260°C at depths of less than 2 km. Stratigraphically the reservoir region can be described as a five-layer sequence that includes Tertiary and Quaternary volcanic rocks, and Mesozoic and Tertiary sediments overlying Precambrian granitic basement. Production is mainly controlled by fractures and faults that are ultimately related to activity in the Rio Grande Rift system. Geophysically, the caldera is characterized by a gravity minimum and a resistivity low in its western half. A 40-mgal gravity minimum over the caldera is due mostly to the relatively low-density volcanics and sediments that fill the caldera and probably bears no relation to deep-seated magmatic sources. Two-dimensional gravity modeling indicates that the depth to Precambrian basement in Redondo Canyon is probably at least 3 km and may exceed 5 km in eastern parts of the caldera. Telluric and magnetotelluric surveys have shown that the reservoir region is associated with low resistivity and that a deep low-resistivity zone correlates well with the depth of the primary reservoir inferred from well data. Telluric and magnetotelluric data have also identified possible fault zones in the eastern and western sections of the production region that may form boundaries to the Redondo Creek reservoir. These data also suggest that the reservoir region is located at the intersection of lineaments that trend north-south and northeast-southwest. Magnetotelluric results indicate deep low resistivity at the western edge of the caldera which may be associated with deep hot fluids. On the basis of geophysical and well data, we make three estimates of reservoir dimensions. The estimates of the areal extent of the reservoir range from 10 to 30 km2, depending on whether the Sulphur Creek or the Valle Seco area is considered to contain deep geothermal resources.
- Michael Wilt and Stephen Vonder Haar
- Published Journal
- Journal of Volcanology and Geothermal Research, 1986
- Not Provided
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Michael Wilt,Stephen Vonder Haar. 1986. A Geological And Geophysical Appraisal Of The Baca Geothermal Field, Valles Caldera, New Mexico. Journal of Volcanology and Geothermal Research. 27(3-4):349-370.