High-yielding aquifers in crystalline basement: insights about the role of fault zones, exemplified by Armorican Massif, France

Abstract

International audienceWhile groundwater constitutes a crucial resource in many crystalline-rock regions worldwide, well-yield conditions are highly variable and barely understood. Nevertheless, it is well known that fault zones may have the capacity to ensure sustainable yield in crystalline media, but there are only a few and disparate examples in the literature that describe high-yield conditions related to fault zones in crystalline rock basements. By investigating structural and hydraulic properties of remarkable yielding sites identified in the Armorican Massif, western France, this study discusses the main factors that may explain such exceptional hydrogeological properties. Twenty-three sites, identified through analysis of databases available for the region, are investigated. Results show that: (1) the highly transmissive fractures are related to fault zones which ensure the main water inflow in the pumped wells; (2) the probability of intersecting such transmissive fault zones does not vary significantly with depth, at least within the range investigated in this study (0–200 m); and (3) high yield is mainly controlled by the structural features of the fault zones, in particular the fault dip and the presence of a connected storage reservoir. Conceptual models that summarize the hydrological properties of high-yield groundwater resources related to fault zones in crystalline basement are shown and discussed

Transmissivity Changes and Microseismicity Induced by Small‐Scale Hydraulic Fracturing Tests in Crystalline Rock

“…The solid lines represent the PI tests, whereas dotted lines correspond to CRI tests. The relationship between transmissivities and fracture frequency (e.g., Ando et al, 2003;Illman, 2005;Park et al, 2004;Roques et al, 2016) is presented in Text S3 and Figure S2 (see supporting information).…”

Dispersion and Mixing in Three‐Dimensional Discrete Fracture Networks: Nonlinear Interplay Between Structural and Hydraulic Heterogeneity

“…In low permeability media fractures and discontinuities are the primary regions for the movement of fluids, involving processes taking place at multiple length scales (Bonnet et al, ). Therefore, their study is relevant for groundwater development (Roques et al, ), geothermal energy (Barbier, ), nuclear waste disposals (Cvetkovic et al, ), and unconventional gas production (Hyman et al, ). However, while in some regions one or several families of discontinuities are well identified (e.g., Äspö Hard Rock Laboratory, Rhén, ), in others, the coexistence of different types of discontinuities, such as bedding planes, fractures, joints, faults and shear zones, foliation (including cleavage) or dykes, makes the definition of families difficult (e.g., Klint et al, ).…”

Análise derivativa de testes de bombeamento em aquíferos fissurais no município de Jundiaí/SP

“…Em oposição, a zona de dano, representada por regiões intensamente fraturadas e desenvolvidas em torno das zonas de falhas, possui valores elevados de condutividade hidráulica (CAINE et al 1996). A viabilidade deste modelo conceitual foi comprovada por inúmeros autores, dentre os quais, MABEE et al (1994), NEVES & MORALES (2007), FAULKNER et al (2010, RAFINI & LAROCQUE (2012), ROQUES et al (2016, cujos resultados demonstraram que zonas com elevados valores de transmissividade situam-se próximos a zonas de falhas.…”