Multi-scale distribution of fractures in crystalline basement,Influence of structural inheritance. Examples of the proximal oblique margins of the Gulf of Aden and Catalonia

La découverte de nombreux réservoirs fracturés dans le socle a considérablement relancé l'intérêt porté sur l'étude de la fracturation du socle. Une meilleure compréhension des relations d'échelles qui caractérisent la géométrie des systèmes fracturés estDevelopment of basement fractured reservoirs in and around igneous rocks have been carried out in recent years. Analyses of field rock analogues are thus required for a better understanding of the scaling characteristics of fracture systems, which coul

Distribution multi-échelle de la fracturation dans les réservoirs cristallins (Influence de l'héritage structural. Exemples des marges obliques proximales du golfe d'Aden et de Catalogne)

La découverte de nombreux réservoirs fracturés dans le socle a considérablement relancé l intérêt porté sur l étude de la fracturation du socle. Une meilleure compréhension des relations d échelles qui caractérisent la géométrie des systèmes fracturés est donc nécessaire, dans le but de guider l interprétation des données régionales et de les extrapoler à d autres échelles. Une cartographie multi-échelle des systèmes fracturés des socles cristallins du Yémen et de Catalogne a été décrite à travers des analyses statistiques des différents paramètres géométriques. Le réservoir fracturé analogue est défini suivant un modèle à double porosité dans lequel les systèmes tectoniques et les systèmes de joints correspondent respectivement à la colonne vertébrale et à la matrice du réservoir. Ces deux entités montrent des propriétés géométriques, réservoir et d échelle contrastées. Dans les systèmes tectoniques, les géométries multi-échelles sont auto-similaires, montrent des comportements fractals et les zones de failles présentent une organisation hiérarchique. Dans les systèmes de joints, le réseau de fractures est dépendant de l échelle et les espacements sont réguliers ou aléatoires. De plus, le rôle de l héritage structural a été investigué. Les principaux résultats montrent que (i) la dimension et l orientation des structures héritées sont des paramètres majeurs qui contrôlent la compétition entre réactivation et néoformation et (ii) le découplage structural entre deux niveaux crustaux possédant un héritage structural hétérogène (e.g. le socle et sa couverture sédimentaire) est contrasté et peut être efficace sans niveau de décollement.Development of basement fractured reservoirs in and around igneous rocks have been carried out in recent years. Analyses of field rock analogues are thus required for a better understanding of the scaling characteristics of fracture systems, which could guide both the interpretation of regional data, and its extrapolation to other different scales. Multi-scale mappings of extensional fracture systems in the crystalline basements of Yemen (panafrican) and Catalonia (hercynian) are described through statistical analyses of several geometrical parameters. The fractured reservoir analogue is defined with a dual porosity model in which tectonic and joint systems correspond to the basement reservoir backbone and matrix respectively. These two end-members reveal contrasting geometrical, reservoir, and scaling properties. In tectonic systems, multi-scale geometries are self-similar , the fracture network shows fractal behavior, and fault zones show hierarchical organization of geometrical parameters such as length, thickness, and spacing. In joint systems, the fracture network is scale dependent with negative exponential length distribution, and shows anti-clustered spacing. In addition, the role of structural inheritance in basement fracture systems has been investigated. Main results show that (i) size and orientation of inherited structures are major parameters which controlled competition between reactivation and neoformation and (ii) structural decoupling between layered crustal levels having heterogeneous structural inheritance (e.g. basement versus sedimentary cover) is contrasting and could be effective without an intermediate decollement level.STRASBOURG-Géologie (674822251) / SudocSudocFranceF

P/T ratio in high-pressure rocks as a function of dip and velocity of continental subduction

International audienc

Geometry and kinematics of continental subduction inferred from 1D thermal modelling of prograde PT path

International audienc

A multiscale analysis of a fracture pattern in granite: A case study of the Tamariu granite, Catalunya, Spain

International audienceThe in-depth investigation of fractured reservoirs is mainly limited to geophysical data that is in 3D and mostly on the scale of hundred meters to several kilometers or boreholes data that is in 1D and at meter to lower scale. The study of outcropping analogues of buried reservoirs is therefore a key tool for the characterization of the fault and fracture network at the reservoir scale. Tamariu granite has been the subject of this study with the aim to analyse faults and fractures from seismic to borehole scale. With the combination of satellite picture at different resolution and field study, we perform a statistical analysis focused of the length and orientation from infra centimeter crack to hundred kilometer length fault. On the whole range of scale studied, i.e. on 7 orders of magnitude, we have defined a length distribution following a power-law with an exponent a ¼ À2. On the contrary to the length that can be modelled with a unique law, the orientation data shows a variation depending on the scale of observation: as the fault and fracture sets are suitable from the regional faults to the centimeter crack, the proportion of the sets varies at each scale of observation

Scaling and geometric properties of fracture systems in Proterozoic basement of Yemen (Al Mukalla area). Tectonic interpretation and fluid flow implications.

International audienc

Scaling and geometric properties of extensional fracture systems in the proterozoic basement of Yemen. Tectonic interpretation and fluid flow implications

International audienc

Tajik Basin and Southwestern Tian Shan, Northwestern India-Asia Collision Zone: 1. Structure, Kinematics, and Salt Tectonics in the Tajik Fold-and-Thrust Belt of the Western Foreland of the Pamir

International audienceSurface, seismic, and borehole data characterize the Neogene-Recent Tajik fold-and-thrust belt of the Tajik basin. The basin experienced little sub-detachment basement deformation, acting as a rigid foreland plate during the Pamir orogeny. The Tajik fold-and-thrust belt contains variable thinskinned structural styles, changing along and across strike as a function of the thickness and facies of Upper Jurassic evaporites, which constitute the basal detachment, and the influence of the surrounding thickskinned belts. The southern Tajik fold-and-thrust belt shows regularly spaced, salt-cored, thrusted detachment anticlines that transition northward into imbricated thrust sheets grouped in oppositely verging stacks facing each other across a common footwall syncline. The width of the fold-and-thrust belt decreases northeastward accommodated by the Ilyak fault, a lateral ramp developed over a seismically active dextral basement fault. The southeastern Tajik fold-and-thrust belt contains massive subaerial salt sheets, formed by squeezing of preexisting salt diapirs. The salt-tectonic domain originates from a local depocenter within the Late Jurassic Amu Darya-Tajik evaporitic basin. Serial cross sections, integrating the structural geometries, yielded minimum thinskinned shortening oriented at~90°to the India-Asia convergence direction, increasing from~93 km in the south to~148 km in the center, and dropping tõ 22 km in the northeast; total shortening-including the foreland buttress-is ≥170 km. Most of the shortening in the central-southern Tajik fold-and-thrust belt occurred by hinterland-vergent, high-displacement back thrusts. The Pamir played a dominant role in the transfer of shortening to the sedimentary infill of the Tajik basin with the Tian Shan acting as a semi-passive buttress