Experimental Study of Acid Fracture Conductivity on Soft Carbonates

Acid fracturing is a well stimulation technique used in carbonate formations. Its success relies upon the creation of conductive pathways that remain open after acid pumping stops. Through acid fracture conductivity experiments, it is possible to optimize treatment variables such as acid type, acid concentration, and flowrate. In this study, eleven Kansas Chalk outcrops and four North Sea cores were tested for acid fracture conductivity. Both carbonate rocks are relatively soft. The feasibility of acid stimulation is investigated. The reaction of these rocks to straight 15% HCl, and to 15% HCl with corrosion inhibitor, surfactant, non-emulsifying agent, scale inhibitor and gelling agent, were analyzed. The variables in the experimental study include: temperature, acid type, acid concentration and contact time. These parameters were selected to mimic the field conditions. The acid tests were performed in a lab setup that reproduces these field settings. In order to quantify the volume of rock dissolved, the rock’s surfaces were scanned before and after acidizing with a profilometer device. The created conductivity was measured for most samples at different closure stresses. In addition, porosity, Brinell Hardness, solubility tests, X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF) and Scanning Electron Microscope (SEM) were performed on selected samples. The results of this study show that including the aforementioned additives in the acid decreased the differential etching of soft carbonates. The effect was seen for both formations. The North Sea cores developed a film on the fracture surface during the acid treatment. After analyzing portions of rock and residue, it was found that this insoluble material was mostly composed of quartz and some clay. Differential dissolution of the North Sea cores was not observed. Therefore, poor conductivity from these cores was obtained under the experimented conditions. In addition, it was also noticed that increasing the contact time from 15 minutes to 25 minutes did not enhanced the resultant conductivity. Furthermore, for both formations, higher volume of rock dissolved did not result in higher conductivity. The Kansas Chalk outcrop produced high conductivity at low closure stress when using straight acid, but it rapidly declined with increasing closure stress. Based on the observed results, acid fracturing stimulation with the tested fluids is not recommended for the North Sea cores. The feasibility of using other methods to increase productivity should be investigated

Experimental Study of Acid Fracture Conductivity on Soft Carbonates

Acid fracturing is a well stimulation technique used in carbonate formations. Its success relies upon the creation of conductive pathways that remain open after acid pumping stops. Through acid fracture conductivity experiments, it is possible to optimize treatment variables such as acid type, acid concentration, and flowrate. In this study, eleven Kansas Chalk outcrops and four North Sea cores were tested for acid fracture conductivity. Both carbonate rocks are relatively soft. The feasibility of acid stimulation is investigated. The reaction of these rocks to straight 15% HCl, and to 15% HCl with corrosion inhibitor, surfactant, non-emulsifying agent, scale inhibitor and gelling agent, were analyzed. The variables in the experimental study include: temperature, acid type, acid concentration and contact time. These parameters were selected to mimic the field conditions. The acid tests were performed in a lab setup that reproduces these field settings. In order to quantify the volume of rock dissolved, the rock’s surfaces were scanned before and after acidizing with a profilometer device. The created conductivity was measured for most samples at different closure stresses. In addition, porosity, Brinell Hardness, solubility tests, X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF) and Scanning Electron Microscope (SEM) were performed on selected samples. The results of this study show that including the aforementioned additives in the acid decreased the differential etching of soft carbonates. The effect was seen for both formations. The North Sea cores developed a film on the fracture surface during the acid treatment. After analyzing portions of rock and residue, it was found that this insoluble material was mostly composed of quartz and some clay. Differential dissolution of the North Sea cores was not observed. Therefore, poor conductivity from these cores was obtained under the experimented conditions. In addition, it was also noticed that increasing the contact time from 15 minutes to 25 minutes did not enhanced the resultant conductivity. Furthermore, for both formations, higher volume of rock dissolved did not result in higher conductivity. The Kansas Chalk outcrop produced high conductivity at low closure stress when using straight acid, but it rapidly declined with increasing closure stress. Based on the observed results, acid fracturing stimulation with the tested fluids is not recommended for the North Sea cores. The feasibility of using other methods to increase productivity should be investigated

Indirect effects of bullying on school mathematics achievement in Chile

Students who experience bullying at school present different negative outcomes, including lower academic achievement. However, the process by which bullying is connected to academic achievement is not clear. Using the Trends in International Mathematics and Science Study (TIMSS) dataset from Chilean schools in 2011, we sought to estimate the indirect effects of bullying on mathematics achievement via two key socio-motivational factors, namely school belonging and students’ engagement. Results of our multilevel latent covariate analyses showed that schools’ bullying rates were predictive of school differences in mathematics achievement, but these effects were explained by broader characteristics of the school environment such as perceived levels of safety and discipline. Crucially, the hypothesized indirect pathway was evident at the within-school level, showing that individual experiences of bullying are related to a poorer sense of belonging with the school as a whole, as well as poorer classroom engagemen

As novas tecnologias de manufatura como instrumento competitivo

Dissertação (mestrado) Universidade Federal de Santa Catarina, Centro Tecnologico, 1990O objetivo geral deste trabalho consiste em demonstrar que as oportunidades que oferecem as novas tecnologias de equipamentos e processos, são fundamentais para a competitividade das empresas de manufatura. Este, inicia-se mostrando a evolução da administração da manufatura e discutindo as causas pelas quais as empresas industriais ocidentais estão sendo cada vez menos competitivas perante seus concorrentes asiáticos, particularmente os japoneses. Conclui-se que os desajustes provêm da excessiva ênfase dada à produtividade e se necessita pensar estrategicamente em relação às decisões de produção. Em consequência disto analisam-se alguns modelos de administração da manufatura, que visam demonstrar que uma poderosa vantagem competitiva pode ser criada mediante uma estratégia de produção. Porém, estes modelos não consideram o potencial de competitividade oferecido pelas "Novas Tecnologias de Manufatura", na formulação, não só da estratégia de produção, como também, na estratégia global da empresa. Na etapa seguinte, descreve-se este recurso, mostrando suas características, seus benefícios estratégicos e discutindo a problemática de sua implementação. Conclui-se este estudo revelando a necessidade de incorporar estas novas tecnologias na escolha de decisões estratégicas, para que possa sobreviver competitivamente no futuro

Context-Dependent Encoding in the Human Auditory Brainstem Relates to Hearing Speech in Noise: Implications for Developmental Dyslexia

SummaryWe examined context-dependent encoding of speech in children with and without developmental dyslexia by measuring auditory brainstem responses to a speech syllable presented in a repetitive or variable context. Typically developing children showed enhanced brainstem representation of features related to voice pitch in the repetitive context, relative to the variable context. In contrast, children with developmental dyslexia exhibited impairment in their ability to modify representation in predictable contexts. From a functional perspective, we found that the extent of context-dependent encoding in the auditory brainstem correlated positively with behavioral indices of speech perception in noise. The ability to sharpen representation of repeating elements is crucial to speech perception in noise, since it allows superior “tagging” of voice pitch, an important cue for segregating sound streams in background noise. The disruption of this mechanism contributes to a critical deficit in noise-exclusion, a hallmark symptom in developmental dyslexia

(Des)articuladas por el cuidado: trayectorias laborales de mujeres chilenas

Este estudio cualitativo explora la experiencia del trabajo de cuidado en las trayectorias laborales de mujeres chilenas, considerando edad y nivel educacional. Para ello, se entrevistaron cincuenta mujeres profesionales y no-profesionales, entre 24 y 88 años, residentes en Santiago de Chile. Los resultados muestran distintos tipos de cuidado y sus relaciones con las trayectorias laborales, a través de: a) cambios de tipo de trabajo, b) salidas y reingresos, c) retiros permanentes y d) desinterés en la maternidad. Se destaca el rol del cuidado en la vida de las mujeres, que puede generarles satisfacción y culpa. Se concluye que persisten roles tradicionales de género en un sistema cultural que limita la gestión social del cuidado y que deja recaer su responsabilidad sobre las mujeres.This qualitative study explores the experience of care work in the labor trajectories of Chilean women, considering age and educational level. To this end, we interviewed fifty professional and non-professional women, aged between 24 and 88, and living in Santiago, Chile. The results show different types of care and their relationships with labor trajectories, through: a) changes in type of work, b) exits and re-entries, c) permanent retirements, and d) lack of interest in maternity. We highlight the role of care in women's lives, which can lead to both satisfaction and guilt. We conclude that traditional gender roles persist in a cultural system that limits the social management of care and that places its responsibility on women.Este estudo qualitativo explora a experiência do trabalho de cuidado nas trajetórias profissionais de mulheres chilenas, considerando idade e nível educacional. Para isso, foram entrevistadas 50 mulheres profissionais e não profissionais, entre 24 e 88 anos, residentes em Santiago do Chile. Os resultados mostram diferentes tipos de cuidado e suas relações com as trajetórias profissionais por meio de: a) mudanças de tipo de trabalho; b) saídas e reingressos; c) retiradas permanentes e d) desinteresse na maternidade. É destacado o papel do cuidado na vida nas mulheres, que pode gerar satisfação e culpa. Conclui-se que persistem papéis tradicionais de gênero em um sistema cultural que limita a gestão social do cuidado e que deixa cair sua responsabilidade sobre as mulheres

Signaling of noncomprehension in communication breakdowns in fragile X syndrome, Down syndrome, and autism spectrum disorder

The ability to indicate a failure to understand a message is a critical pragmatic (social) language skill for managing communication breakdowns and supporting successful communicative exchanges. The current study examined the ability to signal noncomprehension across different types of confusing message conditions in children and adolescents with fragile X syndrome (FXS), Down syndrome (DS), autism spectrum disorder (ASD), and typical development (TD). Controlling for nonverbal mental age and receptive vocabulary skills, youth with comorbid FXS and ASD and those with DS were less likely than TD controls to signal noncomprehension of confusing messages. Youth with FXS without ASD and those with idiopathic ASD did not differ from controls. No sex differences were detected in any group. Findings contribute to current knowledge of pragmatic profiles in different forms of genetically-based neurodevelopmental disorders associated with intellectual disability, and the role of sex in the expression of such profiles