ABSTRACT
Understanding shale petrophysical parameters is of interest due to its direct implications as cap rocks for CO2 or hydrogen storage, waste depositions, and as unconventional reservoirs. The generation and propagation of natural and induced fracture networks in such rocks is highly dependent on the mechanical behavior linked to several sedimentological parameters, as lithological discontinuities or bioturbation. This study is focused on a different sedimentological parameter that consists of trace fossils and their implication on the generation of fluid-assisted fractures, called bedding-parallel veins. In the Austral-Magallanes Basin, Southern Patagonia, Argentina, both geological features, Skolithos Ichnofacies (doomed pioneers trace fossils) and bedding-parallel veins, are numerous, especially at the top of the turbiditic bodies. The trace fossils exhibit U-shaped vertically oriented burrows composed of clean sandstone, partially cemented by calcite, and a spreite in the central part with heterogenous laminated siltstone. Bedding-parallel veins are composed of calcite fibers with some pyrite grains and bitumen. They are located on the top of the trace fossils along the lithological discontinuity between the turbiditic bodies and the impermeable shales. On their surfaces, a radial pattern starts growing from the trace fossils. Moreover, the number of bedding-parallel veins is dependent on the bioturbation intensity. With this study, we infer that trace fossils represent ichnological mechanical discontinuities (IMD) that have a key role in the generation and development of bedding-parallel veins. By correlation, we also suggest that these geological features must be thoroughly studied, especially regarding their potential for the development of induced fracturing networks.
ABSTRACT
Describimos un caso de reemplazo de superficie de cadera en un paciente con artrosis posterior a necrosis ósea avascular y material de osteosíntesis femoral proximal de difícil extracción. Con las prótesis de superficie se logran buenos resultados si la indicación y la técnica quirúrgica son las correctas. En este caso, facilitó mucho la artroplastia, con un muy buen resultado funcional; se evita una cirugía con mayor morbilidad y una tasa más alta de complicaciones y revisiones, como ocurre con los reemplazos de cadera convencionales tras el retiro de la osteosíntesis proximal de fémur. Los cirujanos de cadera atendemos a estos pacientes con frecuencia; estamos seguros de que este tipo de cirugías debe incluirse en nuestro arsenal terapéutico. A pesar de las desventajas de esta artroplastia (fricción metal/metal, curva de aprendizaje, fracturas del cuello femoral), consideramos que, en estos casos, dichas complicaciones están compensadas por la simplicidad del procedimiento.
We describe a hip resurfacing case in a patient with arthrosis after avascular necrosis and proximal femoral osteosynthesis material difficult to remove. Hip resurfacing achieves good results when its indication and technique are correct. In this case, it facilitated the arthroplasty achieving an excellent functional result; avoiding a major surgery and the high rate of complications and revisions, as it occurs with conventional hip replacements after osteosynthesis of the proximal femur. Surgeons frequently face this type of patients; therefore we are convinced that this procedure must be in our therapeutic arsenal. Besides the disadvantages of this arthroplasty (metal on metal friction, learning curve, neck fracture) we consider that they are compensated for by the simplicity of the procedure.
