Flow regime associated with vertical secondary migration

International audienceSecondary migration is defined as the movement of hydrocarbons through relatively permeable rocks from source to trap: a two-phase flow within a porous medium. Depending on the geometry and capillary pressure distributions of carrier beds, secondary migration has both vertical and lateral components. The present paper focuses on that part of the migration where the movement is mainly vertical. Its objective is to propose a description of the dynamics governing the vertical part of secondary migration based on the main physical aspects of two-phase flow in a homogeneous porous medium. The study is illustrated by laboratory observations performed in a vertical, 2-D Hele-Shaw cell filled with a transparent porous medium where the flow of dyed oil invading a wetting fluid is visually observed. These observations help us to understand the effect of buoyant, capillary and viscous forces on the resulting flow, the relative importance of which is characterized by non-dimensional numbers. Extrapolating these observations to natural media, it is proposed that vertical secondary migration can be described as a percolation of disconnected and vertically-elongated stringers. These stringers do not move continuously but as a succession of snap-off and re-feeding events which result in a jerky upward movement. Using parameters characterizing the physical properties of the fluid and of the porous medium, the geometry and the dynamic behavior of the stringers are estimated. The width of stringers occurring during secondary migration in geological media is centimetric and their vertical size ranges from several centimeters to a few meters. An upper limit of the mean upward velocity of stringers is proposed, as well as an estimate of their spatial density and of the minimum, average horizontal distance (decametric) between two stringers. The stringers are sparsely distributed, resulting in a low average oil loss and a high efficiency of the vertical migration process

Kilometer range filamentation

International audienceWe demonstrate for the first time the possibility to generate long plasma channels up to a distance of 1 km, using the terawatt femtosecond T&T laser facility. The plasma density was optimized by adjusting the chirp, the focusing and beam diameter. The interaction of filaments with transparent and opaque targets was studied

Late orogenic carboniferous extensions in the Variscan French Massif Central

International audienceThe Variscan French Massif Central experienced two successive stages of extension from Middle Carboniferous to Early Permian. In the northern Massif Central, the first stage began in the late Visean, immediately after nappe stacking, and is well recorded by Namurian-Westphalian synkinematic plutonism. The Middle Carboniferous leucogranites widespread in the NW Massif Central (Limousin and Sioule area) were emplaced within a crust extending along a NE-SW direction. At the same time, the hanging wall or "Guéret extensional allochton" moved toward the SE. Several examples of the synextensional plutonism are also recognized in central Limousin: Saint Mathieu dome, La Porcherie, and Cornil leucogranites. These examples illustrate the relationship between granite emplacement and crustal scale deformation characterized by NW-SE stretching and NE-SW shortening. In the central and southern Massif Central (Cévennes, Châtaigneraie, and Margeride areas), plutonism is dominantly granodioritic and exhibits the same structural features: NW-SE maximum stretching and overturning to the SE. Middle Carboniferous (Namurian-Westphalian) extension was parallel to the Variscan belt both in the Massif Central and southern Armorican area. This extensional regime was active from the late Visean in the north, while compression dominated in the southernmost domains (Montagne Noire and Pyrenées). The second extensional stage occurred from Late Carboniferous to Early Permian. This event was responsible for the opening of intramontane coal basins, brittle deformation in the upper crust, and ductile normal faulting localized on the margin of cordierite granite-migmatite domes. Data from the coal basins show that the half-graben is the dominant structural style, except for basins located along submeridianal left-lateral faults which have pull-apart geometries. Late Carboniferous extension occurred along the NE-SW direction. The NE-SW maximum stretching direction can be found in the whole Massif Central but is more developed in the eastern part. The extensional direction is transverse to the general trend of the belt, and top-to-the-NE shearing is dominant. Correlations of these two extension directions with neighboring Variscan massifs are discussed

Brain Struct Funct

Opioid receptors are G protein-coupled receptors (GPCRs) that modulate brain function at all levels of neural integration, including autonomic, sensory, emotional and cognitive processing. Mu (MOR) and delta (DOR) opioid receptors functionally interact in vivo, but whether interactions occur at circuitry, cellular or molecular levels remains unsolved. To challenge the hypothesis of MOR/DOR heteromerization in the brain, we generated redMOR/greenDOR double knock-in mice and report dual receptor mapping throughout the nervous system. Data are organized as an interactive database offering an opioid receptor atlas with concomitant MOR/DOR visualization at subcellular resolution, accessible online. We also provide co-immunoprecipitation-based evidence for receptor heteromerization in these mice. In the forebrain, MOR and DOR are mainly detected in separate neurons, suggesting system-level interactions in high-order processing. In contrast, neuronal co-localization is detected in subcortical networks essential for survival involved in eating and sexual behaviors or perception and response to aversive stimuli. In addition, potential MOR/DOR intracellular interactions within the nociceptive pathway offer novel therapeutic perspectives