Pore network properties of sandstones in a fault damage zone

Abstract

The understanding of fluid flow in faulted sandstones is based on a wide range of techniques. These depend on the multi-method determination of petrological and structural features, porous network properties and both spatial and temporal variations and interactions of these features. The question of the multi-parameter analysis on fluid flow controlling properties is addressed for an outcrop damage zone in the hanging wall of a normal fault zone on the western border of the Upper Rhine Graben, affecting the Buntsandstein Group (Early Triassic). Diagenetic processes may alter the original pore type and geometry in fractured and faulted sandstones. Therefore, these may control the ultimate porosity and permeability of the damage zone. The classical model of evolution of hydraulic properties with distance from the major fault core is nuanced here. The hydraulic behavior of the rock media is better described by a pluriscale model including: 1) The grain scale, where the hydraulic properties are controlled by sedimentary features, the distance from the fracture, and the impact of diagenetic processes. These result in the ultimate porous network characteristics observed. 2) A larger scale, where the structural position and characteristics (density, connectivity) of the fracture corridors are strongly correlated with both geo-mechanical and hydraulic properties within the damage zone.

Petrophysical properties of volcanic rocks and impacts of hydrothermal alteration in the Guadeloupe Archipelago (West Indies)

“…c) Simplified geological map of Basse-Terre Island with major volcanic complexes and structures (Boudon, 1988;Mathieu, 2010). Groundmass K/Ar ages from Blanc, 1983;Carlut et al, 2000;Ricci et al, 2015bRicci et al, , 2015aRicci et al, , 2017Samper et al, 2007Samper et al, , 2009. Major faults from Calcagno et al, 2012;Feuillet et al, 2002;Leclerc et al, 2016. d and e) Location map of studied samples with the different rock types and their degree of alteration: d) Basal Complex in the northern part of Basse-Terre Island; e) Vieux-Habitants-Bouillante area.…”

On the Use of Aeromagnetism for Geological Interpretation: 2. A Case Study on Structural and Lithological Features in the Northern Vosges

“…(a) General map of the URG with the main structural features: Vosgian and Rhenish faults; Saverne FF, Saverne Fractured Field; LLFZ, Lalaye‐Lubine Fault Zone; BBFZ, Baden‐Baden Fault Zone (modified after Bossennec et al, 2018), zoom‐in on the boundary zone between the Northern Vosges and the URG on (b) the RTP map and (c) the geological map.…”

Evolution of diagenetic conditions and burial history in Buntsandstein Gp. fractured sandstones (Upper Rhine Graben) from in-situ δ18O of quartz and 40Ar/39Ar geochronology of K-feldspar overgrowths

“…44-35 Ma (Lutz et al 2013)), sedimentation started in mini Fig. 1 Geological context and sampling localities: A Schematic geological map of the URG after Bossennec et al (2018) and Eisbacher and Fielitz (2010) with sampled localities in pink. Major Variscan and Cenozoic faults are represented after Schumacher (2002).…”

“…1 a) E Schematic cross section (modified from Sokol et al (2013)) of the western border of the URG with location of Roemerberg wells Fig. 2 A Chronological chart, modified after Böcker and Littke (2015) and Bossennec et al (2018), placed in the frame of major geodynamical episodes. Paleostress orientations are represented in black for σ1, grey for σ2, and white for σ3; regional stress fields and geodynamical context (Schumacher 2002;Blaise et al 2016).…”

“…2B), resulting in a multi-stage paragenetic sequence (Fig. 2C), strongly dependent on fault activity (Clauer et al 2008;Dresmann et al 2010;Blaise et al 2016;Bossennec et al 2018). The paragenetic sequence of the targeted sandstones is characterised by the first phase of diagenetic clay mineral grain coating, followed by the first generation of K-feldspar overgrowths.…”