Petrophysical properties in faulted basement rocks: Insights from outcropping analogues on the West European Rift shoulders. (September 2021)

• Record Type: Journal Article
• Authors: Bertrand, Lionel; Géraud, Yves; Diraison, Marc
• Is Part Of: Geothermics. Volume 95(2021)
• Publication Date: 2021-09
• Subjects: Outcrop analogue -- Petrophysical properties -- Basement rocks -- Fault zone; Hydrogeology -- Periodicals; Geothermal resources -- Periodicals; Énergie géothermique -- Périodiques; GEOTHERMAL ENGINEERING; GEOTHERMAL ENERGY; GEOTHERMAL EXPLORATION; Geothermal resources; Hydrogeology; Periodicals; Electronic journals; 621.44
• DOI: 10.1016/j.geothermics.2021.102144
• Languages: English
• ISSNs: 0375-6505

Abstract

Abstract: In continental extension settings like the West European Rift, the main target for high-temperature geothermal drillings is the fault zones in basement rocks of the grabens. However, the reservoir properties of these structures remain almost unknown during the predrilling resource evaluations. This study shows the petrophysical evolution in fault zones on three outcropping areas at the basins' shoulders. We highlight three petrographical groups with different petrophysical evolution in the fault zones: granites and granodiorites, metamorphic rocks with schistosity, and massive metamorphic or magmatic facies. It provides a first estimation of their reservoir properties that can be used for dual-porosity modeling. Highlights: The properties evolution depends on mineral alteration vs microcracking process. For granites, petrophysical properties are in agreement with URG deep wells data. The weathered layer at the sedimentary/basement interface is also characterized.