Browsing by Author "Sánchez, Martín"

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    Effect of particle shape and fragmentation on the response of particle dampers
    (SAGE Publications, 2014) Sánchez, Martín; Carlevaro, Manuel; Pugnaloni, Luis
    A particle damper (PD) is a device that can attenuate mechanical vibrations thanks to the dissipative collisions between grains contained in a cavity attached to the vibrating structure. It has been recently suggested that, under working conditions in which the damping is optimal, the PD has a universal response in the sense that the specific dissipative properties of the grains cease to be important for the design of the device. We present evidence from simulations of PDs containing grains of different sizes, shapes and restitution coefficients, that the universal response is also valid when fragmentation of the grains occurs (generally due to intensive operation of the PD). In contrast, the welding of grains (caused by operation under high temperatures) can take the PD out of the universal response and deteriorate the attenuation. Interestingly, we observed that even at working conditions off the optimal damping, the shape of the grains remains unimportant for the response of the PD.
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    Simulación del transporte de agente de sostén en estimulación hidráulica
    (2020) Baldini, Mauro; Pugnaloni, Luis; Sánchez, Martín
    En los reservorios convencionales el hidrocarburo se encuentra embebido en rocas que poseen alta porosidad y permeabilidad, por ello puede fluir con relativa facilidad a través de la matriz porosa. Por este motivo la explotación de este tipo de reservorios se realiza, a grandes rasgos, generando una perforación (pozo) en el reservorio para que el hidrocarburo fluya desde la formación hacia el pozo y luego hacia la superficie. El flujo desde la formación hacia el pozo se origina normalmente debido a la denominada presión de reservorio, que es simplemente la presión que poseen los fluidos en la formación. Luego, el hidrocarburo se eleva a superficie mediante un equipo de bombeo. Aunque es muy poco frecuente, debemos mencionar que en algunos reservorios convencionales, debido a una presión de reservorio alta, puede prescindirse de un equipo de bombeo.
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    Stability and conductivity of proppant packs during flowback in unconventional reservoirs: a CFD–DEM simulation study
    (Elsevier B.V., 2021) Vega, Federico G.; Carlevaro, Manuel; Sánchez, Martín; Pugnaloni, Luis
    We present simulations using a coupled Computational Fluid Dynamics–Discrete Element Method (CFD–DEM) approach for a slurry of millimeter-sized particles in water which is squeezed between two walls and then made flow out though a narrow aperture. The process is akin to the flowback stage in the near wellbore zone of a hydraulic-stimulated well for hydrocarbon recovery. We consider different wall roughness and investigate its effect on particle production, final distance between walls, spatial particle distribution between the walls, and fluid production rate. We have found that the final distribution of particles changes significantly with small variations in the roughnesses of the walls. This in turn leads to production flow rates that may vary up to 50%. Although the main driver of the production for unconventional wells is the propped fracture network, these results suggest that the roughness of the fracture walls seems to play an important role in the final conductivity and therefore in the ultimate recovery.