bluuebunny/crossref_metadata_2025_split huggingface dataset:
CARACTERIZAÇÃO DO POTENCIAL DE BIODISPONIBILIDADE DE METAIS (Zn, Cd, Pb, Cu e Ni) EM SEDIMENTOS DE CORRENTE DO RIO SÃO FRANCISCO
Authors: Vasconcelos F. M. , Almeida D. F. , Santos L. , Moreira T. T. 
Published: January 2016

comum e tem sido alvo de diversas pesquisas com o objetivo de determinar o impacto ambiental desse tipode contaminação. Sabe-se hoje que somente a concentração total de metais nos sedimentos não é um bomparâmetro para a avaliação da toxicidade de metais em sedimentos. Além de ensaios de eco toxicidade érecomendável a realização de ensaio de caracterização geoquímica da concentração de sulfetos voláteispor acidificação e de metais simultaneamente extraídos (AVS/SEM) que é utilizada para a determinação dafração potencialmente biodisponível de metais em sedimento. Sete amostras em duplicada foram coletadasnas margens do rio São Francisco próximo a uma planta metalúrgica de zinco no município de Três MariasMG. Os ensaios de caracterização geoquímica do tipo AVS/SEM dessas amostras sugerem que apesarda concentração de metais totais (Zn, Cd, Pb, Cu e Ni) estarem acima do Nível 1 da norma ambiental dequalidade de sedimentos, o potencial de biodisponibilidade de metais nessas amostras é relativamente baixopara seis dentre sete amostras.Palavras chaves: metais; contaminação; biodisponibilidade; sedimentos. ABSTRACT: In countries with intense industrial activities, sediment contamination by metals is relatively common and ithas being the target of several researches with the goal of investigating the environmental impact assessmentof this type of contamination. It is well known that using only the bulk metal concentration in sediment is notsufficient for estimating the metal toxicity in this media. Besides ecotoxicological tests it is recommended thedetermination acid volatile sulfides and simultaneously extracted metals (AVS/SEM) for the estimation ofthe fraction of potential bioavailability of metal in the sediment. Seven samples in duplicate were collectedfrom the edges of the São Francisco River near a zinc metallurgical plant in the town of Três Marias MG. Thesediment AVS/SEM geochemical characterization test results of these samples suggest that although the metalbulk concentrations (Zn, Cd, Pb, Cu e Ni) from these samples are above the Level 1 of the environmentalregulation for sediment quality, six out of seven samples presented low potential for metal bioavailability.Keywords: metals; contamination; bioavailability; sediments.
ASPECTOS GEOARQUEOLÓGICOS DO SÍTIO CEMITÉRIO CAIXA D’ÁGUA: VALE DO SÃO FRANCISCO - MINAS GERAIS/BRASIL.
Authors: Baggio Filho Hernando , Freitas Mariana de Oliveira , Meneses Thalita Siqueira de , Da Costa Thiago Martins 
Published: January 2016

Esta breve comunicação, tem como proposta apresentar aos leitores, um dos mais importantes sítios arqueológicos a céu aberto ao longo do Vale do São Francisco o Sítio Arqueológico Cemitério Caixa d’Água, localizado no município de Buritizeiro, norte do Estado de Minas Gerais. O projeto de pesquisa é financiado pela Fundação de Amaparo à Pesquisa do Estado de Minas Gerais - FAPEMIG, e tem como objetivo principal entender o padrão de aldeamento pré-histórico do sítio arqueológico. Foi montado uma malha superfial de amostragens, o material coletado será submetido a análises físico-químicas, químicas e mineralógica (classificação dos solos, fracionamento, cor dos solos, mineralogia, entre outras); químicas (pH, Zn, Cu, Ca, Cr, P, Pb e C orgânico Total ), além disso, a caracterização do ambiente físico. Os resultados obtidos poderão elucidar alguns dos principais enigmas arqueológicos do sítio, como por exemplo, os vários momentos de ocupação pré-histórica que ocorreram no sítio arqueológico Cemitério Caixa d’Água.Palavras-chave: Sítio arqueológico, FAPEMIG, solos, geoquímica ABSTRACT: THE CAIXA D’ÁGUA CEMETERY SITE GEOARCHAEOLOGICAL ASPECTS: SÃO FRANCISCO VALLEY- MINAS GERAIS/BRAZIL. This brief communication, has a proposal to present to readers, one of the most important archaeological sites in the open along the São Francisco Valley Cemetery the archaeological site Caixa d’ água, located in the municipality of Buritizeiro, north of Minas Gerais. The research project is funded by the Fundação de Amaparo a Pesquisa do Estado de Minas Gerais - FAPEMIG, and has as main objective to understand the pattern of village's prehistoric archaeological site. Will be mounted, a mesh surface samples (geocoding, geoprocessing, soil, surface geochemistry, etc.). The collected material will be subjected to physical and chemical analyzes (soil classification, division, color of soil and others); chemical (pH, Zn, Cu, Ca, Cr, P, Pb, and total organic carbon), mineralogical analysis of soils, in addition, the characterization of the physical environment. The results may explain some of the major puzzles of the archaeological site, for example, the various moments of prehistoric archaeological site that occurred in the Caixa d’ água cemetery.Keywords: Archeological site, FAPEMIG, soil, geochemistry
O DESGASTE FLUVIAL DA AMETISTA DE BREJAÚBA, MG: UM MÉTODO AUXILIAR DE PROSPECÇÃO
Authors: De Brot Pierre , Karfunkel Joachim , Fernandes Augusto Fonseca 
Published: January 2016

A pesquisa aqui apresentada desenvolve um método para estimar a distância que a ametista percorreu no Ribeirão Brejaúba desua rocha fonte para o seu local de recuperação no sistema fluvial a partir da análise do desgaste. Utilizando amostras que foram coletadasna sua própria origem, em laboratório, com os sedimentos do sistema fluvial simulou-se o desgaste de transporte semelhante ao dosistema fluvial com a utilização do de um tambor rotatório (tumbler). O desgaste foi determinado por uma lupa de mão de 10x e lupabinocular. As curvas de desgaste foram então desenvolvidas em tempo de rotação em relação à perda de peso. Ao comparar o desgastedas amostras a partir do sistema fluvial com as do tumbler, chegou-se à razão de 1 x 10 (distância percorrida no sistema fluvial versus adistância percorrida pela gema no tumbler), respectivamente. Para futura prospecção de ametista em sistemas fluviais com característicassimilares ao da Brejaúba, este método permite a eliminação de muitas estações de amostragem, pois a distância até a fonte pode sermelhor estimada. Representa um método auxiliar de prospecção aluvionar, maximizando o custo/ benefício em relação ao métodoconvencional. Esse método pode ser usado em outros minerais gemológicos como foi realizado para a brasilianita da área de MendesPimentel, em Minas Gerais.Palavras Chaves: desgaste fluvial, ametista, prospecção ABSTRACTFLUVIAL WEAR OF THE AMETHYST FROM BREJAÚBA, MG: AN AUXILIARY METHOD FOR ALLUVIAL PROSPECTING. The research presented here develops a method for estimating the distance that alluvial amethyst has traveled from its source rock to its recovery site inthe fluvial system of the Ribeirão Brejaúba from analysis of the fluvial wear shown on experimental samples. Using samples collected fromthe source region, they were tumbled in the laboratory with sediments from the fluvial system so as to simulate the wear from transport inthat fluvial system. The wear was determined by a hand loupe and 10x binocular loupe. Graphs were then developed showing the time ofrotation versus the weight loss. By comparing the wear of samples from the fluvial system to that in the tumbler a ratio of 1 to 10,respectively, was found. For future prospecting for amethyst in fluvial systems similar to that of Brejaúba, this method permits eliminationof many sampling positions because the distance to the source may be better estimated. This gives an auxiliary method to traditionalfollow-up methods of prospecting maximizing cost/benefits of exploration. This method may be used on other gemstones as has beendemonstrated for brazilianite from the Mendes Pimentel area in Minas Gerais.Keywords: fluvial wear, amethyst, prospecting
A CRATERA DE IMPACTO DO CERRO DO JARAU-RS, BRASIL: UMA ABORDAGEM GEOTURÍSTICA
Authors: Sánchez Joana Paula , Garcia Maria da Glória Motta 
Published: January 2016

Crateras de impacto por meteorito são formações raras no planeta e de extrema importância para o conhecimento da evoluçãogeológica e biológica da Terra por se tratarem de eventos catastróficos que causaram extinções em massa e movimentaram camadasgeológicas. No Brasil sete crateras de impacto estão cientificamente comprovadas, dentre estas, quatro já classificadas como possíveissítios geológicos. A área objeto deste trabalho, o Cerro do Jarau, está localizada no sudoeste do Estado do Rio Grande do Sul, na divisa como Uruguai e insere-se no contexto geológico da Bacia do Paraná. Trata-se de uma feição semicircular de aproximadamente oito quilômetrosde diâmetro, com cristas elevadas, que se diferenciamgeomorfologicamente do Pampa Gaúcho. A região constitui-se num bom exemplo degeossítio no qual o patrimônio geológico pode associar-se ao patrimônio imaterial, entre eles valores culturais e arqueológicos, paraimpulsionar o turismo local com o apoio de estratégias de geoconservação e um plano geoturístico.Palavras chave: Crateras de Impacto, Geoconservação, Geoturismo, Patrimônio Geológico. ABSTRACT THE IMPACT CRATER OF CERRO DO JARAU, BRAZIL: A GEOTURISTIC APPROACH.Meteorite impact craters are rare formations onthe planet and of utmost importance for the understanding of the biological and geological evolution of the Earth because they areregisters of catastrophic events that caused mass extinctions and geological movements. In Brazil seven impact craters are scientificallyproven, among these four already classified as potential geological sites. The area object of this work, Cerro do Jarau, is located southwestof Rio Grande do Sul State, at the limit with Uruguay and is part of the geological context of the Paraná Basin. It is a semicircular featurewith approximately eight miles in diameter, with high ridges, which differ geomorphologicallyof the Pampa Gaúcho. The region constitutesa good example of geosite where geological heritage can join intangible heritage, including archaeological and cultural values, to boostlocal tourism with the support of geoconservation strategies and a geotourism plan.Keywords: Impact craters, geoconservation, geoturism, geological heritage.
Retórica de ruptura e descontinuidade nas ciências da linguagem: um estudo pela historiografia da linguística
Authors: Batista Ronaldo de Oliveira 
Published: January 2016

RESUMO:
Este texto tem como foco de observação, a partir da Historiografia da Linguística, a retórica de linguistas em momentos de ruptura na história do conhecimento sobre a linguagem. Para tanto são colocados sob análise posicionamentos discursivos em um texto que se considera na história da linguística brasileira como o de divulgação inicial da Gramática Gerativa no Brasil, a saber, a resenha que Miriam Lemle fez em 1967 das ideias de Noam Chomsky. A interpetação aqui proposta destaca um episódio do desenvolvimento da linguística no Brasil, acabando por evidenciar de que modo a prática científica é também uma prática discursiva, circunscrita a uma dimensão histórica e social específica.

PALAVRAS-CHAVE:
Historiografia da Linguística, Gramática Gerativa, Retórica de ruptura
Fiber-Optics Results From an Intra-Stage Diversion Design Completions Study in the Niobrara Formation of DJ Basin
Authors: Ramurthy Muthukumarappan , Richardson Joe , Brown Mark , Sahdev Neha , Wiener Jack , Garcia Mariano 
Published: January 2016

Abstract
Hydrocarbon production has been long existent in the Denver Julesburg basin and with the development of horizontal drilling technology the Niobrara has become one of the most economical plays even with lower oil prices. The multi-bench Niobrara formation is the primary target in the basin followed by the Codell. Even with the better economics, the Niobrara and the Codell completions are not optimized yet. The operators are still aiming for more and more stages with lesser spacing thus increasing the costs. The objective of this study is to show that stage spacing can be optimized with low cost diversion technology yielding equal or better production with fewer stages thus lowering costs.
In this optimization study, two Niobrara "C" bench lateral wells from the same pad that are next to each other were selected as candidates. The first well, Well-K was completed with 28 stages geometrically spaced at 153 feet utilizing the perf-n-plug methodology. The second well, Well-L was completed with 20 stages, geometrically spaced at 215 feet, also utilizing the perf-n-plug methodology. Well-L was stimulated utilizing the intra-stage diversion process and had approximately 404,000 lbm less proppant than Well-K. Well-K was completed without the diversion technology. Following stimulation and flowback, Fibercoil with Distributed Temperature Survey (DTS) and Distributed Acoustic Survey (DAS) capabilities were run in both the wells to diagnose the contribution from each perforation cluster. The Fibercoil results clearly showed that Well-L with larger stage spacing and intra-stage diversion had 80% fracture initiation as opposed to 60% with the limited-entry Well-K that had shorter stage spacing. The production results so far are very encouraging for the L-well. The 180-day cumulative oil production for Well-L is almost similar to Well-K with the normalized barrels of equivalent oil (BOE) per foot, BOE/ft. difference being lower by 3%.
This study has clearly shown us that with some additional enhancement intra-stage diversion can be used to optimize stage spacing without compromising production. The post-frac fracture modeling analysis along with the Fibercoil results including warm-back analysis and production for the two wells is presented.
A Family of Unique Diverting Technologies Increases Unconventional Production and Recovery in Multiple Applications - Initial Fracturing, Refracturing, and Acidizing
Authors: McCartney E. S. , Kennedy R. L. 
Published: January 2016

Abstract
This paper covers a brief description of common solid particulate diverters used in stimulation treatments; discusses the development of a unique state-of-the art solid particular diverting system (SPD); and compares it with conventional diverters. Results of four case studies are also presented.
After 10 years of shale/unconventional well completions in the US, operators are still striving to determine the nearly perfect multi-stage fractured horizontal well completion that produces hydrocarbons from all fracture stages/perforation clusters. Why? The most commonly accepted explanation is that complete, uniform fracturing has not been achieved, especially as lateral lengths, number of frac stages, and perforation clusters increased, and stage spacing reduced. Like all liquids, stimulation fluids follow the path of least resistance. In heterogeneous reservoirs, this commonly results in some over-treated zones and some untreated perforation clusters within a stage. An economical solution was found in an old, but newly designed technology: diversion.
Since mid-2014, the new diversion technology for near-wellbore applications has been used in more than 1,050 frac stages (66 wells) and 17 acidizing operations, for 17 different operators in 14 different unconventional plays. The four case histories presented within this paper include a six-well refracturing program in the Haynesville that resulted in average 60-fold production increase; an initial fracture stimulation treatment in the Bone Spring shale, leading to 50% more production than a direct offset fractured well with the same design, but without diverter; a three-well remedial acidizing program in the Woodford shale, Oklahoma, that resulted in significant production increases; and a 12-well initial fracturing program in the Eagle Ford shale, resulting in production rates comparable to or exceeding offset wells.
Fracturing and acidizing treatments have used a number of diversion techniques over the years; common diverting agents include benzoic acid flakes, Gilsonite, and rock salt. All aim to temporarily block high-permeability paths that are taking most of the fluid, thereby shifting subsequent fluids into the next-most permeable path. Still these conventional diverter systems are not engineered with an optimal particle size distribution to yield more effective diversion. Instead, a new state-of-the-art family of diverter systems has been designed with specific particle size distributions that enhance diversion. This unique family of non-damaging and dissolvable solid particulate diverters is applicable for normal and high-temperature reservoirs and effective for near-wellbore and far-field diversion.
Fully-Coupled 3D Hydraulic Fracture Models: Development, Validation, and Application to O&G Problems
Authors: Searles Kevin H. , Zielonka Matias G. , Ning Jing , Garzon Jorge L. , Kostov Nikolay M. , Sanz Pablo F. , Biediger Erika 
Published: January 2016

Abstract
This paper describes the development, validation, and application of new 3D finite element models for a diverse set of oil & gas problems involving fluid-driven fractures. Applications described in the paper include borehole integrity and lost returns, drill cuttings re-injection (CRI), and produced water reinjection (PWRI).
The models were developed and implemented in a commercially available finite element (FE) software package. The models include both cohesive elements (mesh conforms to pre-defined fracture orientation) and extended finite elements (fracture geometry evolves independent of the finite element mesh). Advantages and disadvantages of each approach will be described. The models were validated through comparisons with published analytical asymptotic solutions for limiting values of rock and fluid properties and leak-off conditions (with practical problems of interest lying within these limits). A comprehensive suite of large-scale laboratory experiments were also conducted and models were used to replicate the conditions and results of these experiments. Larger 2D and 3D finite element models were then constructed and used to demonstrate applicability to a broad range of realistic oil & gas problems, including problems with large length and long time scales. Tractable simulation of these problems was enabled by high-performance, massively parallel computing systems.
The models show excellent agreement with published analytical solutions for a broad range of rock and fluid properties and fracturing conditions. The models also show reasonable agreement with laboratory experiments for a similar range of conditions. The models scale up from lab to well scales and have shown practical applicability for a diverse set of challenging oil and gas problems.
Most hydraulic fracture models fall into the categories of fast-running but with simplified physics, or complex physics but computationally impractical for full-scale commercial applications. The models described in this paper have been applied at commercial time and length scales, but also provide for full representation of the complex physics of hydraulic fracturing, as demonstrated by the comprehensive validation with analytical solutions and laboratory experiments.
Comparison of Pseudo-3D and Fully-3D Simulations of Proppant Transport in Hydraulic Fractures, Including Gravitational Settling, Formation of Proppant Banks, Tip-Screen Out, and Fracture Closure
Authors: Shiozawa Sogo , McClure Mark 
Published: January 2016

Abstract
A modeling framework is developed to describe proppant transport (including gravitational settling and tip-screen out) in a hydraulic fracturing simulator that can function as either fully-3D or pseudo-3D. The simulator locally enforces mass balance of fluid and proppant and applies appropriate boundary conditions for mechanical calculations. The simulator uses recently developed constitutive equations that smoothly capture the transition from Poiseuille flow to Darcy flow as the proppant concentration transitions from a dilute mixture to a packed bed. We develop new constitutive relations that enable the model to describe fracture closure against proppant (at either low or high concentration) after the end of injection. We also develop a framework for modeling proppant settling in a pseudo-3D model. The method ensures a continuous solution, which guarantees convergence and accuracy with refinement of the temporal and spatial discretization. The framework allows proppant to settle into a proppant bank at the bottom of the fracture. The proppant bank can grow, remain stationary, or erode, depending on flow conditions. The simulator can describe tip-screen out (TSO) and the tendency for the volumetric flowing fraction of proppant to exceed the volumetric fraction of proppant due to the tendency of proppant to flow at the center of the fracture aperture. Pseudo-3D simulations are compared to the fully-3D simulations for both hydraulic fracturing and long-term production. For hydraulic fracturing, the pseudo-3D simulations are able to substantially reproduce the results from the fully-3D simulations and are far more computationally efficient. The simulation methods are compared using a variety of values for proppant size, fluid viscosity, and proppant density. An optimized proppant schedule is tested in order to improve horizontal proppant placement and prevent excessive tip screen-out. The simulations indicate that because fracture closure can be slow in very low permeability formations, substantial settling occurs after the end of injection, significantly worsening vertical proppant placement. For simulation of long-term production, the pseudo-3D results deviate strongly from the fully-3D simulations, indicating that the pseudo-3D model is not suitable for simulating the production phase, as currently formulated.
Physical Explanation of Non-Linear Derivatives in Diagnostic Fracture Injection Test Analysis
Authors: Barree R. D. , Miskimins J. L. 
Published: January 2016

Abstract
Over the past few years several authors have attempted to explain various non-linear pressure-time derivative behaviors observed in diagnostic fracture injection tests (DFIT's) using mathematical theories and application of conventional pressure transient theory. While based in solid math, these authors have, in some cases, ignored the physical processes that drive the observed pressure behavior. This paper seeks to explain the mechanical and physical processes that can occur during the fracture extension and closure process of a DFIT, with a minimum of equations or abstract mathematics.
Two major sources of non-linear (non-ideal) leakoff behavior are addressed. They have been variously termed "pressure dependent leakoff" (PDL), and "variable compliance leakoff" (also known as height recession, transverse storage, variable storage, and by other names). Both of these pressure-time derivative signatures can be caused by multiple mechanisms, but really represent simple and fundamental changes in the rate of pressure decay during fracture closure. This paper explains the assumptions leading to the ideal linear derivative model, and the real processes that can lead to the observed deviations from this ideal model.
It is hoped that an explanation of the physical mechanisms represented by these tests will lead to a better understanding of the failure conditions of the rock mass, and character of the induced fracture system. Correct interpretation of these tests is critical to design of effective stimulation treatments and to developing an understanding of the post-frac production characteristics of the well.