Fluid-Rock Interactions in a Paleo-Geothermal Reservoir (Noble Hills Granite, California, USA). Part 2: The Influence of Fracturing on Granite Alteration Processes and Fluid Circulation at Low to Moderate Regional Strain

Fracture connectivity within fractured granitic basement geothermal reservoirs is an important factor controlling their permeability. This study aims to improve the understanding of fluid–rock interaction processes at low to moderate regional strain. The Noble Hills range (Death Valley, CA, USA) was...

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Bibliographic Details
Published in:Geosciences (Basel) 2021-11, Vol.11 (11), p.433
Main Authors: Klee, Johanne, Chabani, Arezki, Ledésert, Béatrice A., Potel, Sébastien, Hébert, Ronan L., Trullenque, Ghislain
Format: Article
Language:English
Subjects:
Calcite
Case studies
Chemical elements
Digitization
Earth science
Exploitation
fluid circulation
Fluids
Fracture zones
fracturing processes
Geology
geothermal reservoir
Grain size
Granite
granite alteration
Hills
low to moderate regional strain
Mineralogy
Permeability
Porosity
Reservoirs
Rocks
Sciences of the Universe
Scientific imaging
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Summary:Fracture connectivity within fractured granitic basement geothermal reservoirs is an important factor controlling their permeability. This study aims to improve the understanding of fluid–rock interaction processes at low to moderate regional strain. The Noble Hills range (Death Valley, CA, USA) was chosen as a naturally exhumed paleo geothermal reservoir. A series of petrographic, petrophysical, and geochemical investigations, combined with a fracture distribution analysis, were carried out on samples collected across fracture zones. Our results indicate that several generations of fluids have percolated through the reservoir. An increase of (1) the alteration degree; (2) the porosity values; and (3) the calcite content was observed when approaching fracture zones. No correlation was identified among the alteration degree, the porosity, or the calcite content. At a local scale, samples showed that the degree of alteration does not necessarily depend on the fracture density or on the amount of the strain. It is concluded that the combined influence of strain and coeval fluid–rock interaction processes drastically influence the petrophysical properties of fracture zones, which in turn impact geothermal production potential.
ISSN:2076-3263
2076-3263
DOI:10.3390/geosciences11110433