Antecedentes: El cumplimiento de normas éticas contribuye a la protección de los participantes humanos en una investigación. Objetivo: Describir la utilización de la normativa de ética en investigación por expositores de trabajos libres, XXX Congreso Científico Internacional, Federación Latinoamericana de Estudiantes de Medicina (FELSOCEM), Panamá, 2015. Metodología: Estudio descriptivo transversal. Instrumento autoadministrado previo consentimiento informado escrito. Se realizó un muestreo por conveniencia entre participantes inscritos presentando trabajo(s) libre(s). Se consideró cumplimiento de las normas éticas en investigación 1) contar con aval institucional, 2) aprobación de comité de ética en investigación (CEI) y 3) obtención de asentimiento/consentimiento informado. Se registró la información en base de datos EpiInfo vs 3.5.4 (CDC, Atlanta, EUA). El estudio fue aprobado por CEI Facultad de Ciencias Médicas UNAH y FELSOCEM. Resultados: Participaron 98 asistentes, edad promedio 22 años (desviación estándar +2.53), 60 (61.2%) sexo femenino, procedentes de 12 países, 73 (75.2%) con más del 60% de pensum académico alcanzado. Presentaron 105 trabajos libres: 42 (40.0%) casos clínicos, 63 (60.0%) protocolos/trabajos de investigación (44.4% descriptivo, 38.1% analítico, 17.5% experimental). Cumplieron tres criterios éticos de investigación 33 (31.4%), dos criterios 39 (37.1%), un criterio 26 (24.8%), ningún criterio 7 (6.7%). Discusión: El 56.2% (59) de los trabajos presentados no cumplió con las normas éticas en investigación. En época de pandemia, la revisión ética es aún más relevante. Los eventos científicos de asociaciones estudiantiles ofrecen una oportunidad de fortalecer la conducta responsable en investigación en años formativos, lo cual debe ser promovido por el comité organizador de cada congreso.
This paper presents a case study from a mature oil field subjected to long term injection of fresh water. Multiple, potential oil horizons are encountered in newly drilled wells, however, formation evaluation is very challenging due to mineralogical heterogeneity and mixing of formation and contrasting injected waters altering formation water salinity to variable levels. Conventional logs fail to accurately predict oil/water saturation and reservoir quality under these conditions. Multifrequency dielectric measurements were acquired and inverted using a newly developed radial inversion method, to establish the length of invasion and complex permittivity of both invaded and uninvaded formation layers. Using this method saturations are determined, independent of salinity, and are successfully tied to mineralogy related reservoir quality variations. A multi-frequency, multi-spacing, array dielectric instrument measures formation permittivity with various radial depths of investigation. These high frequency measurements require closely spaced receivers also providing measurements of thin layers at high vertical resolution. An advanced radial model inversion algorithm was developed, which employs a trained, deep-learning artificial neural network (ANN) to invert the large quantity of data acquired. The algorithm resolves the dielectric properties of inner/invaded and outer/uninvaded formation layers. In a subsequent step, the frequency dispersion profile is inverted separately for these two regions in order to determine water saturation, salinity and textural parameters. Complex reservoir structure, variations in mineralogy, long term injection of fresh water for secondary recovery, and use of fresh drilling mud makes it highly challenging to interpret the response of conventional log measurements, leading to uncertainty in identification and assessment of pay zones. The new methodology was successfully applied in this case history to resolve these uncertainties. The study well was drilled with a mud salinity much lower than formation salinity. In zones with shallow mud filtrate invasion, dielectric measurements extend over an area of fluid heterogeneity, from invaded to virgin formation, and a simple homogeneous formation model is not representative. The advanced model considers radial layers of borehole, mud-cake, invaded and uninvaded formation, and correctly inverts for variable formation properties away from the wellbore. Petrophysical results show correct identification and quantification of prospective oil zones well differentiated from wet sands. Independent evaluation of mineralogy is integrated to further understand the saturation variations in productive layers. The information that this technique supplies is of immense benefit to petrophysicists, completion and reservoir engineers engaged in development of mature fields using waterfloods.
fax 01-972-952-9435. AbstractOptimizing production in mature fields depends greatly on proper reservoir characterization. After a certain period of production, a reservoir may exhibit changes in its properties because of changes in formation water salinity arising from water injection, left-behind residual oil in the rock, and changes in pressure regime. These factors, combined with complexities in the original reservoirs properties, such as rapid variations in permeability and oil viscosity, strongly affect the degree of uncertainty in evaluating and predicting productive zones when using only conventional logging methods.These variations affect the responses of most conventional logs. Consequently, traditional log analysis models may fail to provide realistic evaluation results and may not achieve appropriate production forecasts. Common examples of such failures have been recognized when producing high water content from a zone believed to be hydrocarbon or when perforating an interval that does not produce.New logging technologies, such as magnetic resonance imaging (MRI), demonstrate promising formation evaluation results in mature fields. The MRI technology helps to properly distinguish candidate production zones and provide key in-situ reservoir properties, including hydrocarbon type, reservoir quality in terms of permeability and porosity, and barrier zones. The ability of MRI to determine oil viscosity influences the selection and elimination of zones to be produced based on its fluids mobilities. Thus, MRI serves well in the selection of hydrocarbon producing intervals.This paper discusses the effectiveness of applying the MRI technology in characterizing the reservoir fluid properties in the El Furrial field, East Venezuela. It also highlights the value of this technology in minimizing the cost of mis-identified zones for production or testing by identifying best candidate intervals. Verification of the MRI results with actual production testing and/or formation pressure measurements will be demonstrated in the article.
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