Diagenetic evolution of fault zones in Urgonian microporous carbonates, impact on reservoir properties (Provence – southeast France)

摘要

Microporous carbonate rocks form important reservoirs with permeabilityvariability depending on sedimentary, structural, and diagenetic factors.Carbonates are very sensitive to fluid–rock interactions that lead tosecondary diagenetic processes like cementation and dissolution capable ofmodifying the reservoir properties. Focusing on fault-related diagenesis,the aim of this study is to identify the impact of the fault zone on reservoirquality. This contribution focuses on two fault zones east of La Fareanticline (SE France) crosscutting Urgonian microporous carbonates. Overall, 122collected samples along four transects orthogonal to fault strike wereanalyzed. Porosity values have been measured on 92 dry plugs. Diageneticelements were determined through the observation of 92 thin sections usingpolarized light microscopy, cathodoluminescence, carbonate staining, SEM, andstable isotopic measurements (δ ~(13)C and δ ~(18)O).Eight different calcite cementation stages and two micrite micro-fabricswere identified. As a main result, this study highlights that the two faultzones acted as drains canalizing low-temperature fluids at their onset andinduced calcite cementation, which strongly altered and modified the localreservoir properties.