Fracture Spacing Variability and the Distribution of Fracture Patterns in Granitic Geothermal Reservoir: A Case Study in the Noble Hills Range (Death Valley, CA, USA)

Arezki Chabani , Ghislain Trullenque (1, 2) , Johanne Klee , Béatrice A Ledésert (3)

1 UniLaSalle
2 B2R - Bassins - Réservoirs - Ressources - U2R UPJV-UNIL 7511
3 GEC - Laboratoire Géosciences et Environnement Cergy

Scanlines constitute a robust method to better understand in 3D the fracture network variability in naturally fractured geothermal reservoirs. This study aims to characterize the spacing variability and the distribution of fracture patterns in a fracture granitic reservoir, and the impact of the major faults on fracture distribution and fluid circulation. The analogue target named the Noble Hills (NH) range is located in Death Valley (DV, USA). It is considered as an analogue of the geothermal reservoir presently exploited in the Upper Rhine Graben (Soultz-sous-Forêts, eastern of France). The methodology undertaken is based on the analyze of 10 scanlines located in the central part of the NH from fieldwork and virtual (photogrammetric models) data. Our main results reveal: (1) NE/SW, E/W, and NW/SE fracture sets are the most recorded orientations along the virtual scanlines; (2) spacing distribution within NH shows that the clustering depends on fracture orientation; and (3) a strong clustering of the fracture system was highlighted in the highly deformed zones and close to the Southern Death Valley fault zone (SDVFZ) and thrust faults. Furthermore, the fracture patterns were controlled by the structural heritage. Two major components should be considered in reservoir modeling: the deformation gradient and the proximity to the regional major faults.

Mots clés: fracture network variability Death Valley granite spacing distribution fracture intensity P 10 geothermal reservoir characterization; fracture network variability; Death Valley; granite; spacing distribution; fracture intensity P 10; geothermal reservoir characterization; fracture network variability Death Valley granite spacing distribution fracture intensity P 10 geothermal reservoir characterization

Domaines: Sciences de la Terre

Arezki Chabani, Ghislain Trullenque, Johanne Klee, Béatrice A Ledésert. Fracture Spacing Variability and the Distribution of Fracture Patterns in Granitic Geothermal Reservoir: A Case Study in the Noble Hills Range (Death Valley, CA, USA). Geosciences, 2021, 11 (12), ⟨10.3390/geosciences11120520⟩. ⟨hal-04166797⟩